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\i PREFACE 

This research work was undertaken in the psychological labora- 
tory of Columbia University. To Professors Cattell and Wood- 
worth, and Dr. Poffenberger I owe a debt of gratitude for encour- 
agement and helpful criticism. Grateful acknowledgment is also 
given Professors Thorndikeand Strong, and to the subjects who so 
wilHngly gave their time and many valuable suggestions. 



^0^C^2 



THE EFFECT OF DISTRACTION ON REACTION-TIME 



CHAPTER I 
STATEMENT OF THE PROBLEM 

An unwelcome influence which has played a more or less im- 
portant role in reaction experiments has been the factor of such 
accessory stimuli as noises and similar disturbances. The exact 
influence of this factor has never been measured, although several 
experimenters^ have spoken of its presence and have tried to elimi- 
nate its influence from the laboratory, or disregard the data obtained 
when any disturbance was present. 

But it is important to measure the influence of this factor. 
Such measurements may very well form the basis for conclusions 
relating to business, social, and educational life. 

Although any extrinsic influence used in the laboratory is purer, 
simpler, and more controlled than any similar condition which may 
arise in everyday life, yet the effect upon the physical and mental 
processes will be the same, relatively. However, the important 
factors of interest, emulation, satisfaction, ideals, etc., must be 
considered in the complex everyday life as influencing results. 

It is the purpose of this investigation (1) to determine the 
effect of a stimulus, which occurs at a definite time before the 
stimulus to which the subject must react, on the reaction time to 
the latter stimulus; (2) to determine whether a subject by practise 
can finally ignore the distraction stimulus to the extent that no 
noticeable effect occurs in the reaction time; (3) to determine the 
effect of reacting under one set of distracting conditions on the 
ability to react under other conditions; (4) to show the effect of 
practise on simple reaction time and on reaction time under dis- 
traction. 

iWundt, "Physiological Psychology," 2, p. 355, 1887, Todd, "Reaction 
"to Multiple Stimuh," Archives of Psychol., 1912, No. 21, p. 56. 

Note. — As the work by Todd has recently reviewed the work on reaction- 
time experiments only such references will be made herein which are necessary 
to substantiate methods, conclusions, etc. A more recent study has been made 
by Henmon, "Psychol. Researches of James McKeen Cattell," Archives op 
Psychol., No. 30, 1914. 

Fere, "Sensation et Mouvement," 26-50, 1887. 

Guisseppi Corberi, Rivisti di Psicologia, 1914, 9, 4^2; 460, 480. 

1 



2 EFFECT OF DISTRACTION ON REACTION-TIME 

Briefly stated, the problem concerns the effect of distraction 
on reaction time, and the effect of practise in deahng with dis- 
tractions. 

Other subordinate problems will be treated in their proper 
sequence. A statement of these minor problems is made on 
page 26. 

Reaction experiments were used as the basis of this investiga- 
tion, as the processes involved in the reaction experience are 
fundamental to behavior in its complexer forms. 



CHAPTER II 

HISTORY OF REACTION-TIME WITH RELATION TO DISTRACTION 

I. General Survey 

To summarize briefly what different experimenters have meant 
by distraction is difficult. Some experimenters have found a 
certain stimulus to be a real distraction in some particular cases, 
but when other experimenters have used the same distracting 
stimulus under different conditions the results have often been 
contrary to previous results. Thus the power of a stimulus to 
distract the attention does not seem to remain constant. 

If the distraction is often repeated, we grow accustomed to it, 
and have little difficulty in meeting the demand which it lays upon 
us.^ Or the distraction may be so monotonous from the very 
beginning of its introduction that it loses its distraction power very 
soon.2 

1. Definition. — Because of these conditions much confusion 
has arisen concerning the meaning of a distraction. We commonly 
believe that a distraction is not effective so long as maximum at- 
tention can be given to the main stimuli or task. This view con- 
siders a distraction as something which has enough influence to 
divide or distract, or divert the attention from some task in the 
focus of consciousness. If the maximum attention can be given 
to the task the distraction is not effective. 

2. Methods of Study. — The study of the relation of distraction 
to attention has proceeded along two lines. One is the single task 
method, the other the double task method.^ They have frequently 
been called the distracting method, or the method of distracted 
attention,^ and the method of simultaneous activities or distributed 
attention. In the first case the attention is distracted, in the 
second case divided. 

By the distraction method the subject attends to a definite 
task while some distraction is introduced. The purpose of the 
distraction is to reduce the degree of attention given to the main 
task. 

1 Kulpe, "The Problem of Attention," The Monist, 1903, 13, 45. 

2 Swift, Amer. Jour. Psychol, 1892-3, 5, 10. 

' Geissler, Amer. Jour. Psychol., 1909, 20, 486. 

* Wundt, " Grundz. d. Physiol. Psychol.," 1st ed., 745-49, 1874. Obersteiner, 
Brain, 1879, I, 447 f. Kulpe, The Monist, 1903, 13, 44, 45. 

3 



4 EFFECT OF DISTRACTION ON REACTION-TIME 

In the second method distraction may or may not be present. 
Two mental processes are involved which are supposed to occupy 
simultaneously the focus of consciousness. 

Although this classification is generally accepted some con- 
fusion may arise concerning the notion of attention.^ Distraction 
will mean different things when concerned with different views of 
attention. Distraction or division of the attention may thus mean 
a reduction in the concentration. More things have come into 
consciousness to which attention must be directed, thus there is a 
greater spread, or less concentration. It may mean a decrease in 
clearness,® or it may even mean a decrease in vividness, or degree 
of attention'' or a lessened excitability of all the processes concerned 
in the apprehension and reaction to the contents of perception.^ 

II. Historical Survey 

Obersteiner used reaction time as a basis for the measurement 
of attention.^ His distractions were a music box, a tolerably 
strong induction current for cutaneous stimulation, and a kaleido- 
scope with changing figures for visual distraction. When the 
music ceased just before the stimulus was presented to which a 
reaction was made the reaction time was increased. All the dis- 
tractions affected the simple, muscular reactions. As the time 
between the distractions and the stimulus to which the reactions 
were made was not carefully controlled it is difficult to interpret 
his results. Nor were the distractors uniform in their influence 
for they affected the various subjects differently. Wundt also 
noticed that when a noise occurred just before the stimulus to which 
a reaction must be made the reaction time was increased; if the 
noise and the stimulus occurred simultaneously there was no 
noticeable effect upon the reaction time.^" 

Cattell, in his investigation of the influence of degrees of atten- 
tion upon reaction time, used three metronomes as distractions. 
When these metronomes were allowed to beat and ring rapidly the 

^ " Popular psychology . . . confuses in its idea of attention that of a faculty, 
the operation of which produces certain changes in the mental life; that of an 
activity — the activity of remarking, noticing, observing — always diverted upon 
some definite content which is the immediate occasion of its existence; and, lastly, 
that of a state, in which we continue for a longer or shorter time unaffected by 
changes in the contents of our consciousness." — Kiilpe, The Monist, 13, 42. 

8 Lipps, "Grundtatsachen d. Seelenlebens," p. 134, 1883. 

^Kulpe, "Outhnes of Psychology," 441, 1895. 

8 O. Ktilpe, "The Problem of Attention," The Monist, 1903, 13, 48. 

9 Brain, 1879, 1, 447 ff. 

10 "Physiol. Psychol.," 1st ed., 447 f., 1879; 2d ed., 243, 293, 355, 1887; 
5th ed., Ch. III., 1903. 



HISTORY OF REACTION-TIME 5 

reaction time to a light stimulus was slightly increased, but the 
reaction time to a sound was not changed by the disturbance. 
When the subject was busied by beginning with any number and 
adding 17 after 17 to it, the time of the reactions was greatly 
lengthened, as he could not attend so well to the movements in- 
volved in making the reaction. ^^ 

Bertels used a hght as a distraction and another light for a 
stimulus to which the reaction was made. The distracting light, 
however, acted as a preparatory or warning signal; thus it was in 
no sense a true distractor. The experimenter thought the interval 
of 2| seconds between the two lights was especially favorable for 
reacting. Multiples of this period were also favorable.^^ 

Swift,^^ in a variety of experiments, found the reaction time to 
be increased by distraction, whether the distraction occurred in 
the same sense as the stimulus to which reaction was made, or in 
a different sense; and whether the subject's attention was directed 
towards the reaction or towards the distraction. Some of his 
results follow. 

The subject reacted to the sound of a faUing ball, and was dis- 
turbed by a metronome beating 120 times per minute. In one 
series his attention was directed towards the reaction, in another 
series towards the metronome. The reaction times, in a, were as 
follows : 

Attention to reaction 122, M.V., 12; control series, 103, M.V. 9. 
Attention to metronome, 158, M.V., 14; control series, 110, M.V., 7. 

The reaction time was slowed in each case, but more when at- 
tention was directed to the metronome than when it was directed 
towards the reaction. 

Again, the subject reacted to the flash of a Geissler tube, and 
was disturbed by flashes of light reflected in a mirror, through a 
hole in which the light of the Geissler tube appeared. The number 
of disturbing flashes varied, as shown in the following table : 

Reaction without Distraction Reaction mth Distraction 

Stimulus Time M.V. Number Kind of Distract. Number Time M.V. 

Light 143(r 10a 100 60 flashes per min. 120 195<r 14(r 

120 flashes per min. 120 197 13 

180 flashes per min. 120 190 16 

540 flashes per min. 100 171 15 

" Mind, 1886, 6, 237, 238, 242. 

12 "Versuchen iiber die Ablenkund der Aufmerksamkeit," Dorpat, 1889. 
(Thesis.) 

13 "The Disturbance of the Attention," Amer. Jour. Psychol., 1892-3, S, 1-19. 



6 EFFECT OF DISTRACTION ON REACTION-TIME 

The following table gives the choice reactions to the sound of a 
falling ball. The disturbance was a definite number of ticks per 
minute of a metronome.^* 

Reaction without Distraction 
Stimulus Time M.V. Number 
Sound.... lOSo- 9<r 100 



Reaction with Distraction 




Kind of Distraction 


Number 


Time 


M.V. 


40 ticks of metro- 








nome per min. . . 


..100 


206cr 


18(r 


80 ticks of metro- 








nome per min. . . 


..100 


210 


19 


120 ticks of metro- 








nome per min. . . 


.. 90 


191 


18 


160 ticks of metro- 








nome per min. . . 


..100 


208 


19 


200 ticks of metro- 








nome per min. . . 


..100 


206 


17 



When the disturbance was 180 flashes of light each minute and 
the subject was required to react by making a choice between two 
movements in response to either a red or an olive light the results 
were as given below: 

Reaction with no distraction: 258o-, M.V., 23<r, No. of Reactions, 10. 
Reaction with distraction 273cr, M.V., 25(r, No. of Reactions, 110. 

When the subject reacted to the auditory stimulus the time 
was 123 0", M.V., 8 o-, No. of reactions, 80. When he reacted to the 
same stimulus but with the flashes of light as a disturbance the 
results were as follows :^^ 

Number of Flashes of Light 

60 

120 

180 



Time 


M.V. 


No. of Reactions 


160(r 


13(T 


100 


141 


9 


100 


148 


11 


100 



When the subject reacted to the flash of the Geissler tube and 
the disturbance was the ticking of the metronome the effect was 
as follows : 



Number of Ticks 


Time 


M.V. 


No. of Reactions 


60 


176(7 


10<r 


100 


120 


190 


12 


100 


180 


174 


11 


100 



The average of one hundred reactions to the same stimulus 
without the distraction was 159 a, M.V., 10 o-.^^ 

" Swift, op. cit., pp. 5 and 8. 
1^ Swift, op. cit., p. 14. 
1^ Swift, op. cit., p. 15. 



HISTORY OF REACTION-TIME 7 

Drew attempted to measure the attention by varying its in- 
tensity.^'' Thus he arranged a series of increasing degrees of com- 
plexity which should make greater and greater demands on the 
mind, until the attention should pass from a fully concentrated 
state to a completely distracted state. But in this he was not very 
successful. He remarks that although his figures are in substantial 
agreement with those of other experimenters who worked under 
like conditions they are not satisfactory. The failure to obtain 
satisfactory results seems to be due to the great diversity of the 
material with which he worked and the presence of numerous 
uncontrolled influences. 

The distractions consisted of: 

1. Reading a text 

(a) silently, 
(6) aloud. 

2. Naming letters 

(a) in direct order in the text, 
(6) in reverse order, 

(c) on a drum, seen one at a time; the fixation of one letter 
seen through a slit. 

3. Multiplication, e. g., 6 x 19, etc. 
The stimuli were given 

1. By a fall apparatus and consisted of: 

(a) letters, 
(6) colors, 

(c) diagrams, 

(d) factors to be multiplied, 

(e) numbers from one to ten. 

2. Orally: 

(a) factors to be multipUed, 
(6) numbers from one to ten. 

The reactions were made on a five- and ten-finger keyboard 
and with a mouth key. Drew states that greater stress was laid 
on the introspective observations made during the course of the 
experiments than upon the chronometric data obtained. 

The effect of a disturbance on both the reaction-time and the 
time required to make a definite movement was determined by 
Moore. 1^ His subjects reacted to the sound of a sound hammer. 

^'' Amer. Jour. Psychol, 1895, 7, 533, 534. 

" "Reaction-time and Movement," Psychol. Rev. Mon. Sup., 1904-5, 6, 1-86. 



8 EFFECT OF DISTRACTION ON REACTION-TIME 

The distractions were: 

1. The process of addition. 

2. Sensory stimuH : 

(a) a continuous noise made by the interrupter of an induc- 
tion coil, 
(6) The noise of this coil accompanied by a slight shock 

received by holding the electrodes in the hand. This 

shock was not painful. 

(c) An intermittent sound made by a metronome beat- 

ing seconds. 

(d) A very loud warning signal for reaction. 

His results are summarized in the accompanying table. 



Reactions to an Auditory Stimulus (Moore^^) 



When the Disturbance Was the Con- 
tinuous Sound on the Induction 
Coil 



&3 



. 164o- 
(13) 



168* 
(12) 
160 

(12) 



B.... 145 

(13) 
C... 151 

(18) 
156 



D. 



(13) 
191 

(12) 



170 

(13) 



18(r 



20 



14 



16 



18 



17 



26 



16 



202(7 
(9) 
162 
(13) 
169 

(9) 
166 
(12) 



179 

(12) 
164 
(12) 
169 



165 

(13) 



t- 



36<r 



11 



17 



17 



17 



11 



(12) 

162 12 

(12) 



13 



When the Disturbance Was the 
Sound of an Induction Coil Ac- 
companied by a Continuous 
Electric Shock 



s 

SQ 



146o 



(14) 



D.. 



i^ 



17o 



e a Q 

(i) <^ ^ 



173 

(13) 
172 
(12) 



172 
(12) 
212 
(10) 
232 
(14) 
173 
(12) 



" Op. cit., 50-53. 

* 168fj- becomes 159o- if a very long reaction, 266(r, is excluded. 



23<^ 



177<r 
(12) 

166 18 
(10) 



18 



13 



45 



34 



16 



HISTORY OF REACTION-TIME 9 

When the Disturbance Was a Metro- When a Loud Warning Signal Pre- 

nc 

B.. 



D. 



Beatinc. 


] Seconds 




( 


:eded the Reaction 






158<T 


39(7 166cr 


28o- 


A. 


. . . 1290- 


16(7 


154(7 


19(7 


(8) 
164 


(11) 
30 






(9) 




(26) 
153 


19 


(9) 








180 
(10) 


27 


(34) 
166 
(26) 
158 


32 
17 


148 


16 240 


30 


B. 


... 147 


14 


(38) 




(12) 


(9) 
190 


20 




(11) 








164 


(12) 
27 179 


20 


C. 


... 142 


14 






(12) 


(11) 






(13) 









The figures in parenthesis indicate the number of cases. 

Moore concludes that the effect of a continuous noise made 
during a series of experiments by the interrupter of an induction 
coil was to lengthen the reaction-time, and also to a slight extent 
the movement-time-^*^ "The effect of this same noise accompanied 
by a slight shock, received by holding the electrodes in the left 
hand, was to lengthen still more the reaction-time. In like manner, 
the movement made under the influence of two disturbances was 
as a rule slower than that executed during a single disturbance. 
The effect of the metronome beating seconds was to lengthen the 
reaction-time but there was no apparent effect on the movement- 
time. A very loud signal for reaction was followed by a quicker 
movement than that of reactions made with the usual tap of the 
hammer." 

Breitweiser investigated the state of attention in the interval 
between the "Ready!" signal and the stimulus for reaction. The 
subjects were required to add as rapidly as possible a printed column 
of figures, but to cease when the "Ready!" signal was given and be 
ready to react to the sound of the sound hammer. The adding was 
then to be resumed till the next "Ready!" signal was given. The 
results showed a general slowing of reactions after all intervals 
(1-10 seconds), but practise quickly increased the speed. When 
the adding was not interrupted but continued after the "Ready!" 
signal was given. The results showed a general slowing of reactions 
(1-10 seconds), but practice signal and the reaction made "on the 
side" the time of reaction was further increased.-^ 

20 Moore, p. 56. 

21 Breitwieser, "Attention and Movement in Reaction-time," Archives op 
Psychol., 1911, No. 18, pp. 19, 31, 32. 



10 EFFECT OF DISTRACTION ON REACTION-TIME 

Todd used light as a stimulus but preceded it by an electric 
shock or a sound and an electric shock. The stimuh were separated 
by a definite interval and reaction was always to the light which 
occurred last. Four intervals were used between the stimuU as 
follows: 360 o-, 180 <t, 90 a, 45 o-. The results of 200 reactions for 
each interval are given below.^^ 

Reaction to a Light Stimulus when Preceded by a Sound and an Electric 

Shock 

Interval Time M.V. 

360<r 201.5tr 8.8ff 

ISO 208.4 18.6 

90 176.9 8.0 

45 168.5 7.7 

Reaction to a Light Stimulus when Preceded by an Electric Shock 

360<r 195.1<r 5.7o- 

180 220.3 6.3 

90 174.4 7.8 

45 169.5 10.1 

The simple reaction-time, when no preceding stimulus was 
present, was 185.8 a, and 175.6 a, for the two subjects employed. 

The 180 0- interval seems especially favorable for the distraction 
influence. The author states that the sound produces a disturbance 
which partially passes away during the interval of 360 <x which 
follows. However, the electric shock occurs before the excite- 
ment has entirely passed and starts another excitation which does 
not pass away before the hght stimulus occurs to which the subject 
reacts. "Thus, the reaction to hght is partially inhibited by the 
inertia of the previous disturbance." The full motor discharge 
that is usually set off by the light when used alone has been some- 
what drained off in the other disturbances, and the reaction time is 
thus longer than when hght appeared alone. The inhibitory effect 
is similar for the interval of 180 o-. But the intervals of 90 a and 
45 0- cause a decided decrease in the reaction-time not unlike the 
decrease caused by increasing the intensity of the stimulus or of 
using simultaneous stimuli. All the figures which the author 
presents are not in harmony with his theory of explanation, for 
the time of reacting with the 180 a interval is longer than when 
the 360 a interval was used. 

The following bibliography deals with distraction but without 
relation to reaction-time. 

22 Todd, "Reaction to Multiple Stimuli," Archives of Psychol., 1912, No. 
21, pp. 53, 4, 6. Also, Table XVII., p. 38. 



HISTORY OF REACTION-TIME 11 

Distraction as a factor in motor phenomena has been observed 
by: 

Loeb, Archiv f. d. ges. Physiol., 39, 1886. 

M. Fere, Sensation et Movement, 1887. 

M. Fere, Jour, de V Anatomic et de la Physiologic, 1901. 

Bowditch and Warren, Jour. Physiol., 11, 25-64, 1890. 

Binet, Rev. Philos., 19, 1890. 

Bliss, Yale Studies, 1, 1893. 

Hofbauer, Pfliiger's Archiv f. d. ges. Physiol., 68, 546-59, 1897. 

Henri, L'Annee Psychol., 3, 1897. 

Welch, Amer. Jour. Psychol, 1, 283-306, 1898. 

Sanct6 de Sanctis, Zeits. f. Psychol., 17, 1898. 

Cleghorn, Amer. Jour. Physiol, 1, 336-345, 1898. 

McDougall, Brit. Jour. Psychol, 1904. 

Peter, Archiv f. d. ges. Psychol, 8, 1906. 

Corberi, Rivista de Psicologia, Anno. 9.=N. 5, 1913. 

Bogardus, Amer. Jour. Sociol, 17, 1912. 

Billings, Psychol Rev., 11, No. 2, 1914. 

Distraction as a factor in the study of attention has been 
referred to as follows: 

Mtinsterberg, Psychol. Rev., 1, 1894. 

Miinsterberg, Zeits. f. Psychol, 1, 1890. 

Hamlin, Amer. Jour. Psychol, 8, 1896. 

Moyer, Amer. Jour. Psychol, 8, 1896. 

Birch, Amer. Joxir. Psychol, 9, 1897. 

Darlington and Talbot, Amer. Jour. Psychol, 9, 1897. 

Binet and Henri, L'annee Psychol, 3, 1897. 

Toulouse et Vaschide, Comp. rend, de soc. de biol, 11, 1899. 

Stevens, "A Plethysmographic Study of Att.," Amer. Jour. Psy., 16, 1905. 

Geissler, Amer. Jour. Psy., 473-529, 1909. 

Breitwieser, op. cit., pp. 17, 30, 1911. 



CHAPTER III 

EXPERIMENTAL PROCEDURE 

Two rooms were used for the experiment. The subjects sat 
in a dark room, in which walls, ceiling, floor, tables and apparatus 
were painted black. The room was 24 by 14 by 14 feet, and was 
lighted by a 12 c.p. carbon filament light at a distance of 10 ft. at 
the left and back of the subject. This bulb was enclosed and the 
light came from the end, only, through two sheets of white tissue 
paper. With this amount of light it was just possible for the subject 
to see the point at which the light stimulus would appear. This in 
fact was the only purpose of the light. When the touch stimulus 
was given the room was well lighted from overhead by a 100-wt. 
tungsten light. This was necessary as the subject himself adjusted 
the touch key. However, as soon as the key was adjusted, the 
subject placed his hand on the reaction key, then closed his eyes 
until after the reaction was made.^ 

I. Production of the Stimuli to which Reaction was Made 

Three forms of stimuli were used, viz., light, sound and touch. 
Each of these was presented alone, and also with sound, light and 
touch distractions. 

A regular order of presentation was followed both in the training 
and in the control experiments. If the order had been changed 
from day to day certain constant errors might have been eliminated; 
but in this experiment better control was obtained by a regular 
order of precedure (see p. 33). 

1. Light Stimulus. — The light appeared on a dark gray back- 
ground through a circular opening 5 mm. in diameter. The 
background or screen was 24 by 30 inches, and was placed approx- 
imately 10 inches from the eyes of the subject. As an adjustable 
head rest was used, and as the screen was also adjustable in height, 
the stimulus was constant in position for all persons. 

The light stimulus was produced by a flash of a Geissler tube in 

^ The room was ventilated with an electric fan when the experiment was not 
in progress. The temperature was uniform tliroughout the year. This constant 
factor tends to eliminate the variable error which might be aUributed to tem- 
perature. 

12 



EXPERIMENTAL PROCEDURE 



13 




^r-_-4l=|r-4---3--tr{-^|-^ 




14 EFFECT OF DISTRACTION ON REACTION-TIME 

circuit with the secondary circuit of an induction coil.^ The coil 
was rated at one half inch spark of about 100 flashes per second, 
though a test showed the spark to be somewhat stronger than this 
with the current used. The intensity of the current through the 
primary coil was .8 ampere. Martin has stated that primary 
currents not exceeding 0.8 to 1 ampere intensity give;^sparks of 
virtually equal duration, other factors remaining equal.^ 

The coil was connected with four dry cells (C^) in parallel. These 
in turn were connected in parallel with the university dynamo 
current (116 V. d. c), with one 16 c.p. carbon filament lamp (Li) 
in parallel for resistance. 

The flash through the Geissler tube, and the chronoscope, were 
controlled by a double contact key (Kie) devised for this purpose. 
The current flowed continuously through the primary coil of the 
inductorium, while an experiment was in progress i. e., while a set 
of 10 reactions was made. This required about thirty or forty 
seconds. The secondary circuit was short-circuited through the 
coil by the upper contact on the key (Kie) due to the greater re- 
sistance of the tube. To give the stimulus, the upper contact was 
broken. This directed all the current to the tube which overcame 
its resistance and made the spark in the tube, while a contact made 
by the same downward pressure of the key started the chronoscope. 
These two acts, the breaking and the making of contacts, occurred 
simultaneously, with little chance for variation. 

This arrangement reduced the variable error due to irregularity 
in starting the induction coil, etc., which has entered into many 
experiments, and practically eliminated the constant error of the 
flash. No change was noted from day to day in the intensity* of 
the light. But even a change of 50 per cent, in the light intensity 
will make a difference of only a few sigma in the reaction-time.^ 
As the hght of a Geissler tube is different from the light we usually 
see, and this in itself might influence the reaction time, yellow sheets 
of gelatine were used to make the light white. This eliminated the 
strangeness and did not greatly lessen the intensity. The light by 

2 Cattell, Phil Studien, 1886, 3, 458-9. Berger, Phil. Studien, 1886, 40-41. 
Patrizi, "La Graphique psychometrique de rattention," Archives italiennes de 
Biologie, 22, pp. 189-196. Salow, Psychol. Studien, 1913, 8, 6, 508. Swift, 
Amer. Jour. Psychol, 1892, 5, 1-19. Seashore, loiva University Studies in Psychol., 
1899, 2, 66. 

» Martin, Amer. Jour. Physiol, 1910, 26, 183-188. 

^Berger, Phil Stud., 1886, 3, 64. Wundt, "Phys. Psychol.," 351, 1887. 
Slattery, "Stud, from Yale Psychol Lab.," 1892, p. 71. Cattell, op. ciL, p. 396, 
1893. Froeberg, Archives of Psychol., 1907, No. 8, p. 33. Todd, op. cit., p. 7. 

^ Froeberg, op. cit. 



EXPERIMENTAL PROCEDURE 15 

photometric measurement was 0.8 c.p. The distracting light was 
2 c.p.« 

The latency of any tube is very small as the pressure is only 
about 2 mm. Dodge by his photographic method found the latency 
to be .01 second. Dunlap noted it as somewhat less. By the 
arrangement used here the tube seemed to reach its full intensity 
instantaneously. A photographic plate falling before the tube 
as it was flashed revealed no increasing intensity in the hght. 
Cattell in some of his earlier experiments noticed that the tube he 
used grew to its full intensity slowly enough to be observed. But 
Helmholtz^ showed, as remarked by Martin,^ that the induced 
current attains its maximum intensity at the instant the spark 
ceases to pass across the broken primary circuit. 

2. Sound Stimulus. — The sound stimulus was produced by a 
sound hammer {H\) of standard form^ placed on a solid table, 
directly in front of the subject at a distance of about 3 feet. No 
deduction has been made in the reaction times for this distance, 
which would decrease the indicated time by 3 <r, since the results 
are used only for comparative purposes. 

The sound hammer was adjusted till no noise was perceptible 
from the contact made by the electro-magnets. ^'^ The anvil was 
covered with a thin, smooth sheet of lead foil to insure perfect 
contact. The hammer was adjusted to fall 2 mm. A felt pad 
above the hammer prevented any noise from the rebound. 

The magnets of the sound hammer were operated by four dry 
cells (Cs), wired in a manner similar to the cells operating the 
induction coil. A current of 4 volts and 0.3 ampere was main- 
tained by means of a rheostat (R2) in series. 

The sound was tested from time to time by means of a falling 
steel ball, weighing 8 grams. Judged by two persons, the sound 
was similar to the ball falling on the same anvil from a height of 
10 mm.ii 

^ Some trouble was experienced at first due to the noise made by the current 
to the Geissler tube but this was eUminated by using larger and better-covered 
wire with perfect connections and free from contact with other wires or apparatus. 

^ Poggendoif's Annalen der Physik u. Chemie, 1851, 83, 505 ff. 

^Amer. Jour. Physiol, 1910, 26, 181. 

9 Myers, "Experimental Psychol., II., p. 42, 1911. Todd, op. cit., p. 6. 

1° The hammers are so constructed that the hammer strikes the anvil before 
the electro-magnets make the contract. The hammer bar is bent down by the 
pull of the magnets and when the current is broken springs up with a metallic 
sound not unlike "ping." This was corrected by making the hammer strike the 
anvil simultaneously with the contact of the magnets or even after the magnet 
contact was made. 

^1 The sound of the hammer, however, was reported by some subjects during 
the course of the experiment to vary in intensity. This change was obviously 



16 EFFECT OF DISTRACTION ON REACTION-TIME 

3. Touch Stimulus. — The touch stimulus was produced by the 
touch key (Ti) previously used and described by Cattell and Dol- 
ley.^2 The hammer weighed 15 grams and fell from a perpendicu- 
lar distance of 25 mm. The surface giving the blow was 3 mm. in 
diameter and made of brass. 

The area stimulated was the back of the inner side of the index 
finger of the left hand midway between the first and second joints. 

The procedure in case of touch was slightly different from that 
of sound and light. The type of touch key used made it necessary 
for the subject to reset the key after each stimulus. This he did 
with his right hand, then replaced the hand on the reacting key, 
the operation requiring from 4 to 6 seconds. The room was well 
lighted for this part of the experiment, in order to permit the 
subject (S) to locate immediately the touch key and the reacting 
key. As soon as he replaced his hand upon the reacting key, he 
closed his eyes and awaited the stimulus. ^^ This procedure probably 
tended to make the reactions of the sensory type, though results or 
introspection failed to prove of which type the reactions were, if 
wholly of either type. It seems possible that the procedure did 
prevent any tendency to anticipate the stimulus or to use the dis- 
traction as an aid when the tendency appeared. 

The same current which was used for the sound hammer was 
used for the magnets of the touch key by means of a two-point 
switch. 

The period of actual stimulation was only a few sigma, and was 
subject to no variations that could affect the reaction time.^^ 

II. Reagent's Key 

The reagent's key was of the regulation telegraph type {Kr); 
100 grams pressure was sufficient to make a contact. The range 
of movement at the point of contact was 2 mm. All the subjects 
found this arrangement agreeable. The key was mounted on a 
weighted block, and was moved to any part of the table to suit the 
subject's convenience. The subject reacted by releasing the key 
in any convenient manner; all subjects actually reacted by a 
finger and wrist movement. 

a subjective change, but such changes may account for some of the variability 
in the time of reacting. 

12 Oj). cit. Illustrated, p. 413, see Table XII., p. 414; also p. 409. Froeberg, 
op. cit., quotes part of the same table, p. 9. 

"KUlen, B., "The Effects of Closing the Eyes upon the Fluctuations of 
Attention," Amer. Jour. 1904 Psychol., 15, 512. 

" See Froeberg, op. cit., and Wells, G. R., "The Influence of Stimulus Dura- 
tion on Reaction-time," Psychol. Rev. Mon., 1913, 15, No. 5, pp. 59, 60. 



EXPERIMENTAL PROCEDURE 17 

Cattell found the wrist movement to give the fastest reaction 
with one subject and the finger movement with another subject. ^^ 
Bryan found the elbow to be the most rapid joint for the tapping 

test.16 

III. The Distracting Stimuli 

Three forms of distraction were used, Hght, sound, and touch. 
The distraction apparatus was operated mechanically by the make 
and break of the mercury contact of an electrical metronome. The 
current was derived from the University dynamo current (116 V.) 
with lamp resistance (L2). The metronome made 36 beats in 
30 seconds, and a contact was made every two beats as only one 
mercury contact was used. 

1. The Light Distraction was produced by three tungsten lamps 
(25 w.) (Ld) which, as well as the sound hammer (^^2) and touch 
instrument (T2), to be mentioned, were wired in circuit with the 
metronome, the current to the different pieces being controlled 
by the necessary three-points witches (S2 and S3). The lamps were 
enclosed in a box behind the background screen. Two cm. above 
the aperture through which the light from the Geissler tube was 
flashed was another aperture of the same size, i. e., 5 mm. in di- 
ameter, covered with one sheet of white translucent paper. Through 
this circular opening the light from the three lamps was flashed as 
the metronome made contact.'^^ 

2. Sound Distraction. — A second sound hammer (H2) was used 
for this distraction. Both the quahty and intensity of the noise 
were different from the sound stimulus. The hammer was adjusted 
to fafl 5 mm., and its noise was equal in intensity to that of a steel 
ball weighing 8 grams falling 45 mm. The hammer was placed 2 
feet to the right of the first hammer and 3 feet, 10 inches in front 
and to the right of the subject. 

3. Touch Distraction. — Touch distraction was produced by a 
falhng weight, supported by a series of levers to give it proper range. 
The weight was pulled up 2 cm. by the contact of two large electro- 
magnets (7^2) with one arm of a lever. The breaking of the circuit 
by the electric metronome allowed the weight to drop.^^ This 

15 Op. cit., p. 410, Table. 

16 "Voluntary Motor Ability," Amer. Jour. Psychol., 1892, 5, 149. 

I'' The lamps for resistance (L2) were in the room of the experimenter and 
flashed out at each contact made by the metronome. This gave the experi- 
menter assurance that the distraction was always working properly. 

1^ Considerable difficulty was encountered with the mercury contact, es- 
pecially in connection with the touch apparatus, due to the volatilization the 
sound of which seemed to be transmitted to the electromagnets in the S's room 
and caused a shght sound. Much of this was overcome by using a soft copper 



18 EFFECT OF DISTRACTION ON REACTION-TIME 

weight weighed 70 grams and fell 2 cm. Due to the hindering 
action of levers the blow exerted was equal only to a weight of 20 
grams falling without impact. 

The contact was made on the back and right side of the second 
finger of the left hand between the first and second joints. The area 
of stimulation was 5 mm. in diameter. The contact point of the 
weight was 2 mm. square and made of wood fiber. The first and 
second fingers of the left hand were placed astride of a triangular 
block of wood (w) fastened to the table. This kept the hand 
stationary. 

IV. Instructions to the Subject 

In general: "When the signal is given, place the fingers on the 
key as if to telegraph and press the key down. When the stimulus 
appears, release the key as quickly as possible." 

Reactions to light: "When a light appears within the small 
white circle release the key as quickly as possible." 

Reactions to light with light distraction: "A light will appear 
within the small white circle, and another light, slightly different 
in intensity, will appear in the opening directly above the white 
circle. React as before, i. e., only when the light within the white 
circle appears. Give no special attention to the light above. The 
two will never appear simultaneously." 

Reactions to light with sound distraction: "React to the light 
only. Give no attention to the sound" (position indicated). 

Reactions to light with touch distraction: "A weight will touch 
you on the second finger. React as before to the light stimulus. 
Give no attention to the touch." 

Reactions to sound: "When the sound is heard (indicated) react 
as quickly as possible." 

Reactions to sound with sound distraction: "React to the sound 
as before; give no special attention to the extra sound." 

Reactions to sound with touch distraction: "The weight will 
touch you on the finger as before. Keep the fingers in the same 
position. React with the right hand as before but not until you 
hear the sound." 

needle, by removing the waste occasionally from the mercury, and by covering 
the mercury with melted paraffin. Tliis hardened and prevented oxidation 
though it had to be renewed quite often. Near the close of the experiment 
Prof. Dodge called my attention to a mercury key devised and used by E. G. 
Martin (Amer. Jour. Physiol., 1910, 16, 183, 188) which could have been used 
successfully in this experiment. The key is devised to break the circuit by 
cutting the mercury. As the point of contact is beneath the surface no volatili- 
zation occurs. Another arrangement of a slightly different principle is described 
by Lombard {Amer. Jour. Physiol., 1902, 8, 20). 



EXPERIMENTAL PROCEDURE 19 

Reactions to touch: "When the weight hits you on the first 
finger of the left hand, react with your right hand." 

Reactions to touch with touch distraction: "A weight will 
touch you on the left hand as mentioned before, when you reacted 
to light or to sound. Another will touch you on the first finger as 
previously. React to this last stimulus, but give no special atten- 
tion to the other." 

In general: "At the close of the set, a signal to rest will be given. 
Release the key and rest till the ready signal comes again." 

At the close of the experiment, the subject was asked: "Did the 
other stimuli distract you? Which ones distract you most? How?" 

"State your physical condition as excellent, fair, or poor." 

"Give any remarks and introspections you may wish to give." 

V. Method of Recording 

The reaction times were recorded with a Hipp chronoscope, of 
the older tj^pe, the one improved and used by Cattell and Dolley.^^ 

The chronoscope was controlled by a small gravity chronometer 
of the fall-screen type.^'^ This had been previously tested with 
the large gravity chronometer figured and described by Cattell 
and DoUey.^^ The chronometer was adjusted for a standard 
interval of 100 a.^^ Before each experiment 10 or more control 
readings were made and the chronoscope adjusted by increasing or 
decreasing the current, by the aid of a rheostat (Rhi), as was 
necessary to secure a mean variation of less than 1 a- per 100 aP 
The average deviation for any series of readings never exceeded 
0.7(7. 

The current for the chronoscope was obtained from a battery 
of 9 gravity cells (d) kept fairly constant at 7 volts and 0.1 ampere.^* 

24 Todd, op. cit., pp. 8, 9. 

19 Berger, Phil. Studien, 1886, 3, 93. Cattell & DoUey, op. cit., pp. 395, 396; 
also, note 1, p. 397, 1893. Klilpe and Kirschmann, Phil. Studien, 1893, 8, 
153 f. Muller and Pilzecker, Zeit. J. Psychol. Erganzungs bd. I., 292 f., 1900. 
Titchener, "Exper. Psychol.," Inst. Man'l, Quantitative, pp. 325, 327, 335, 1905. 
Edgell and Symes, Brit. Jour, of Psychol, 1906, 2, 85, 86. 

20 The wheel contact in this chronometer is identical, though smaller, with 
that of the larger instrument. See Cattell and Dolley, op. cit.. Fig. 4, 399. 

21 Op. cit., p. 397, 1893. Cattell, Phil. Studien, 1894, 9, 397. Titchener, 
"Textbook of Exp. Psychol.," Stud. Man'l, p. 152, 1905. Ins. Man'l (fig. — ), 
p. 344, note 1, 343. Dunlap, Brit. Jour. Psychol, 1911, 4, 55. Myers, "Exp. 
Psychol," II., 43, 50, 1911. Todd, op. cil, p. 8, 1912. 

22 Titchener, op. cit., p. 329. 

2« Cattell and Dolley, op. cil, p. 406. Myers, op. cil, II., p. 49, 1911. 



20 EFFECT OF DISTRACTION ON REACTION-TIME ■ 

VI. Distribution op Apparatus 

The head rest {H^), the large screen in which the light stimuli 
appeared, the two sound hammers (Hi and ^^2) the touch key (Ti), 
and the accompanying apparatus for touch distraction {T2), the 
reagent's key (Kr), and six switches {Si, S2, S3, Si, S5, Se) were 
on the table before which the subject sat, in the dark room.^^ The 
chronoscope, the chronometer, rheostats (Ri and R2), induction coil, 
metronome, lamp resistances (Li and L2), electric counter, and two 
keys {KiE and K2e) were placed in an adjoining, almost sound-proof 
room, in which the experimenter sat. 

The preparatory signal was given from E's table with an electric 
key (Rs)- The gong was removed from a small electric bell and a 
small plate of sheet metal substituted. This was covered with a 
sheet of rubber and the clapper adjusted for a very small amplitude. 
The arrangement thus devised was placed on the head-rest (Sr) 
just below the chin of the subject. The sound was very faint and 
dull, and very different from that of the sound of the hammer. 
Two taps were used as a preparatory signal, and four taps indicated 
that the 10 reactions were completed. The subject signalled to the 
experimenter (E) during the course of the experiment, if necessary, by 
removing his hand from the key, and thus starting the chronoscope. 

VII. Procedure 

After sufficient time for adjustment was allowed, the preparatory 
signal (2 taps) was given, then 3 seconds later the first stimulus was 
given, the chronoscope was then started and in approximately 3 
seconds the second stimulus was given and so on, till 1 1 were given.^^ 
The concluding signal was then given (4 taps), the chronoscope 
stopped, the reading for the total of the 10 reactions made and 
recorded, the chronoscope adjusted and the second set of ten re- 
actions was taken in like manner, except that the first reaction 
was now recorded. This was repeated five times when the simple 
reactions were made, but ten times when the distracting stimulus 

25 The room in which the S sat was not entirely sound proof. It did not 
adjoin the street, had no windows, but two doors. Only occasionally did any 
noise occur outside the room which may have affected the S's reaction-time. 
These were always noted in the introspections. When noise did occur the ex- 
periment was discontinued till condition changed. 

2^ This method of taking 10 reactions before reading the chronoscope permits 
a great number of reactions to be made in a comparatively short time, and with 
ease. It has the disadvantage of not taking account of the variability of the 
separate reactions. This is hidden in the average. It is possible to watch 
the chronoscope and even make note of irregular reactions, as they occur, but 
seldom was this last done in this experiment. 



EXPERIMENTAL PROCEDURE 21 

was added. About 10 seconds elasped between each set of re- 
actions. At the end of each series of 100 reactions a rest period of 
at least 5 minutes was given. In most cases the 150 reactions con- 
cluded the experiment for that day.^'^ 

VIII. The Relation of the Stimulus to the Distraction 

When a distraction was applied, it recurred at regular intervals 
of If sec. The stimulus to reaction was never given at the same 
instant as the distraction, but either § sec. from the beginning of 

,1 I r iPi I II II I I 11 l^ 'l 1 ' n ' ' I ' ^ I' ' I ' 'I ' ' I ' 'I'^i ' ' [^ ' l" 'I' ' I ' ' I' * I 1 ^ 

Fig. 2. The relation of the stimulus to which the subject reacted to the 
distraction stimulus. The O indicates the point in time at which the stimulus 
occurred to which reaction was made. The X indicates the point at which the 
distraction occurred. The long vertical lines indicate the ticks of the metro- 
nome. The smaller divisions represent thirds of a second. 

the interval, in the middle of the interval, or about ^ sec. before 
the end of the interval. This lack of uniformity prevented any 
rhythmical tendencies. Even one-fifth second variation is enough 
to prevent the subject from adopting definite rhythmical action. 
In most cases the subjects did not become aware of the relation of 
distraction and stimulus, as they were directed each day to react 
to the stimulus given, and to give no special attention to the 
distraction. 

In each case the distracting stimulus had more intensity or 
volume than the stimulus to which reaction was made. No attempt 
was made to make the difference between the distraction and the 
stimulus equal in all cases, as this would be very difiicult. 

No doubt it would have been possible, by the discrimination 
time method, to obtained equal subjective differences by selecting 
differences which were perceived in the same time.^^ However, 
the difference used never appeared excessive to the subject, nor 
so great as to place the distraction completely in the foreground 
to the detriment of the main stimulus. The attempt was made to 
have just enough difference to prevent confusion, or reaction to the 
wrong stimulus due to the inability to distinguish between the two. 
All the subjects were able to distinguish the two stimuli even from 
the very beginning. 

27 In the beginning only two sets (20 reactions) were taken with simple 
stimuli, but it was found that this was not enough to allow S to get adjusted and 
reach his normal limit. It seemed that S made improvement till 30 or 40 re- 
actions were made, and then became fairly uniform. 

28 Henmon, op. ciL, 9-11. 



22 EFFECT OF DISTRACTION ON REACTION-TIME 

IX. Simple Reaction with Distraction as Opposed to 
Adaptive Reaction 

It may be well, at this point, in order to avoid some unnecessary 
confusion, and to meet one possible objection, to distinguish between 
simple reaction with distraction and adaptive reaction or reaction 
with choice, which at first may seem to be involved in this experi- 
ment. 

Simple reaction involves but one stimulus, while adaptive, 
or reaction with choice must have at least two stimuli between 
which to choose. Both are presented to consciousness. One can 
not be neglected for the other, and no reaction (unless premature) 
can follow till both or all are compared, or one judged in the Hght 
of the others, no matter whether several movements or the single 
movement is used in reacting. 

In adaptive reaction both discrimination and choice are in- 
volved. When one of two stimuli is presented, the subject must dis- 
tinguish which has been presented, before any movement toward a 
reaction can be made. The choice of right or left hand, or of any 
particular finger must be made and then the proper reaction given 
to the stimulus. This process involves the higher centers and does 
not become reflex quickly, as each stimulus demands continually 
the process of distinction and selection. 

The adaptive reaction gives opportunity for false reactions which 
occur more or less frequently. On the contrary, false reactions 
need never occur when reacting under distracting conditions. The 
subjects reported that there was seldom, if ever, any tendency to 
make false reactions, and few occurred. 

X. Premature Reactions 

If the subject reacted before the stimulus appeared, the reaction 
would be a false reaction. These would not influence the recording 
apparatus. If the subject reacted just as the experimenter gave 
the stimulus, the reaction would be a synchronous reaction. As the 
subject makes the reaction at the time the experimenter gives the 
stimulus the recording instrument would fail to move, or show but a 
very few sigma at the most. 

As a rule, in premature reacting the subject reacts a few sigma 
after the stimulus has been given, although he has not yet perceived 
the stimulus. It is the reactions of this type which vitiate results 
as they so nearly approach the subject's normal reaction time as to 
leave the experimenter in doubt about them. Thus several reac- 
tions 5 to 10 0- too short may occur but only one or two reactions 
which the experimenter recognizes with certainity as premature. 



EXPERIMENTAL PROCEDURE 23 

Let us suppose that the normal reaction of a subject is about 
116 <r to a sound stimulus. After a short practise period he makes 
this reaction quite frequently. When an occasional reaction of 
less than 100 a- occurs no injustice is done the subject if this reaction 
is designated as premature. But suppose, while the normal reaction 
to a sound stimulus is 116 <r, that a few reactions 105 a in length 
occur. It is not impossible for the subject to make such reactions, 
but they are more probably premature though it is impossible to 
tell in any system of registering the time whether they are true or 
premature reactions. Thus there may be several reactions 5 <x 
or 10 (T less than the normal reactions used in a series but only one 
or two reactions which the experimenter recognizes with certainty as 
premature. Although these last premature reactions may be 
excluded from the list, the general average of the series will still 
be too small due to the other short reactions, or the strong tendency 
to make premature reactions.^^ 

The best method to follow in the above case is to vary slightly 
the time between the "Ready!" signal and the presentation of the 
stimulus. 

Premature reactions rarely occurred in this experiment, and 
only then when the interval between the signal and the stimulus 
was the longest. 

The introspections of the subjects are valuable in determining 
these premature reactions, but only when the reaction is very short. 
The subject rarely knows that he has made a premature reaction, 
if the reaction is about equal to his normal time of reacting. 

While a few short reactions were made by two subjects, E and 
F, the attempt was made to avoid these by emphasizing again and 
again the directions, and if necessary discontinuing the work till a 
later period. 

XI. The Subjects 

All the persons who served as subjects were interested in psy- 
chology, and were connected with the university either as student 
or instructor while they were serving as subjects. Two of the 
persons in the practice group were familiar with reaction time ex- 
periments and apparatus in a general way (Subjects C and E). 
Subject B was an experienced subject having served both as subject 

29 For a time one subject tried to make the noise of the sound hammer and 
the slight "ting" of his key synchronous as a musician does his time with the 
metronome. Another applied the same to touch and attempted to react just as 
the key touched his hand. All will admit that such attitudes tend to produce 
premature reactions. 

False reactions could not be recorded as the chronoscope would not operate 
if the S broke the circuit previous to the making of the circuit by the experimenter. 



24 EFFECT OF DISTRACTION ON REACTION-TIME 

and experimenter in similar work. Of the control group only three 
persons had any general knowledge of reaction time work (Subjects 
W, Z, X). 

The data obtained from the control group afforded an adequate 
check on the data of the practise group. Without such data it 
would be unsafe to attribute the decrease in the reaction time to 
the practise received in the training period. The time which inter- 
vened between the preliminary and final control test might account 
for the decrease. Such data, of course, are absolutely necessary in 
determining the amount of transfer which occurs in a practise 
group. The data of the control group in both the preliminary and 
final tests are found in Tables XXVI.-XXXIII. 

XII. The Nature of the Training 

The subjects in the practise group may be divided into three 
groups on the basis of the character of the training. In the case 
of all the subjects there was a period of training in reacting to a 
certain stimulus with a definite distraction present which was much 
longer than the period of training in reacting to the other stimuli. 

1. Subjects A and B. — Subjects A and B reacted to a light stim- 
ulus throughout the experiments. The first distraction intro- 
duced was light. The main part of the training was in reacting 
to a light stimulus with a light as a distraction. After this training 
the light distraction was replaced by a sound distraction, and this 
later replaced by a touch distraction. Thus A and B reacted to a 
light stimulus under the influence of a light distraction, then to 
light when accompanied by a sound distraction, then to light with 
a touch distraction present. 

2. Subjects C and D. — Subjects C and D reacted to a sound 
stimulus with sound as a distraction. In this they received their 
main training. This was followed by reactions to sound with light 
as a distraction, and then by reactions to light with touch as a 
distraction. 

3. Subjects E and F. — The training of E and F was shghtly 
different from the training of C and D in one respect. In order to 
note the effect of distraction upon a practised performance or a 
performance near the limit of practise, E and F were trained in 
reacting to sound without any distraction present. At the close 
of this period of training they reacted to the same sound stimulus 
with a sound distraction present. The sound distraction was then 
replaced by a light distraction, and this in turn was replaced by a 
touch distraction. With the exception of the first special training 
in reacting to sound, the training of C and D, and E and F was 
identical. 



EXPERIMENTAL PROCEDURE 25 

By introducing this period of training in simple reaction it is 
possible to so acquaint the subject with all the extrinsic influences 
which enter into the experiment that they will have no influence 
on his reaction-time. Then, when the distraction is introduced, 
what change really occurs will not be distorted by the presence of 
these other influences. 

XIII. Attitudes 

In any experiment the attitude of the subject toward the act 
or process which he is to execute has an important influence on the 
result. This is especially true in the present experiment. The 
subjects were making a long practise series of reaction-times, as 
well as developing a power to resist the influence of distractions. 
The work was routine, and was continued over a long period of time. 
The subjects had but a very general knowledge of the results ob- 
tained from day to day. The various conditions of health, fatigue, 
diurnal changes, etc., tended to cause changes in the efficiency of 
individuals which in turn influenced their attitude.^'' 

There is always the possibility that the subject may ignore from 
time to time the directions given for guidance. This may be done 
consciously or unconsciously, but it usually occurs when the subjects 
attempt to change their methods of action. At certain times it 
seemed that one or two of the subjects in this experiment attempted 
to use the distraction as an aid in reacting; the futility of this 
procedure manifested itself immediately, but even with the best 
trained subjects some range must be allowed for chance reactions. 
On the whole, however, the subjects were able to follow the in- 
structions implicitly and thus to maintain a uniform attitude 
throughout the experiments. 

*" " The most important fact about the curve of efficiency of a function under 
two hours or less of continuous maximal exercises is that it is, when freed from 
daily eccentricities, so near a straight line and so near a horizontal hne. The work 
grows much less satisfying or much more unbearable, but not much less effective. 
The commonest instinctive response to the intolerabiUty of mental work is to 
stop it altogether. When, as under the conditions of the experiments, this re- 
sponse is not allowed, habit leads us to continue work at our standard of speed and 
accuracy. Such falling off as does occvu- is, in the writer's opinion, due to an 
vmconscious reduction of the intolerability by intermitting the work or some parts 
of it."— Thorndike, "Educational Psychol.," III., 69. 



CHAPTER V 

THE EFFECT OF DISTRACTION UPON REACTION-TIME IN THE 

PRESENT STUDY 

I. As A Preliminary Survey, the Following Problems May 
BE Proposed for Solution 

1. The effect of a light distraction, a sound distraction, or a touch 

distraction on reaction-time. 

(A) With trained subjects. 

(B) With untrained subjects. 

(C) With subjects trained in reacting to the stimulus before 

distraction was introduced. 

(D) Within the daily work curve. 

2. The effect of practise on distraction. 

(A) Is the distraction effect eliminated by practise? 

(B) Does the distraction have greater effect on a practised 

or unpractised performance? 

(C) Is the time for daily adaptation to the distraction reduced? 

(D) To what degree is variability reduced? 

3. The "warming up" period in the daily work. 

4. The most effective distraction. 

5. Some extrinsic influences. 

Figures 3 to 8 give a graphic representation of Tables I. to 
XVII. The ordinates represent reaction time in sigma, while 
the abscissae represent periods or sittings in the experiment. Each 
curve is divided into three parts as three different distractions were 
used. The sohd line represents the reaction time with distraction; 
the broken line the time without distraction which served as the 
daily control test. The star with the arrow attached indicates the 
performance of the subject in the preliminary test before practise 
began. What gain occurred was made without further practise 
in the same performance, but on account of practise in other 
performances. 

In the curve for C there is given in addition to the regular curves 
the smoothed curve for reaction-time both with and without dis- 
traction. In addition to the curve for D there is given also a 
graphic representation of the P.E. for this same curve. It may be 
noted that there are only two points at which the two areas overlap 

or meet. 

26 



EFFECT OF DISTRACTION ON REACTION-TIME 



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^ 




£ "« o is 

*o j^ o i~ 


» 


I ^ =^' , 1 






> 
XI 



X! 



X! 






O 



fe 



EFFECT OF DISTRACTION ON REACTION-TIME 



33 



II. Order of Procedure 

The subjects were given training in the following order: 

Practise Group 
1. Subjects A and B 

(A) Preliminary control test (See p. 34.) 
(J5) First practise series 



Stimulus 


Distraction 


Light 


Light 


(C) Second practise series 




Stimulus. 


Distraction 


Light 


Sound 


(D) Third practise series 




Stimulus 


Distraction 


Light 


Touch 


(E) Final control test 




2. Subjects C and D 




(A) Prehminary control test 




(B) First practise series 




Stimulus 


Distraction 


Sound 


Sound 


(C) Second practise series 




Stimulus 


Distraction 


Sound 


Light 


(D) Third practise series 




Stimulus 


Distraction 


Sound 


Touch 


(E) Final control test 




3. Subjects E and F 




(A) Prehminary control test 




(B) First practise series 




Stimulus 


Distraction 


Sound 


None 


(C) Second practise series 




Stimulus 


Distraction 


Sound 


Sound 


(D) Third practise series 




Stimulus 


Distraction 


Sound 


Light 


(E) Fourth practise period 




Stimulus 


Distraction 


Sound 


Touch 


(F) Final control test 





34 EFFECT OF DISTRACTION ON REACTION-TIME 

In each of the practise series above the subjects first made 50 
reactions to the stimulus, then 100 reactions to the same stimulus 
with the distraction, at each practise period. The preliminary 
control test and the final control test which were given to all of the 
subjects in both the control group and the practise group consisted 
of the following work : 

Stimulus Distraction No. of Reactions 

Light None 50 

" Light 50 

" Sound .50 

" Touch 50 

Sound None 50 

" Sound 50 

" Light 50 

" Touch 50 

Touch None 50 

" Touch 50 

III. Comparisons 

For ease of comparison the tables of the present study are 
grouped together (see pages 72 to 106). The sequence is indicated 
under the topic, "Order of Procedure." While the work of each 
individual is indicated in a separate table the attempt has been 
made to keep the work of exactly the same nature together to 
allow easy comparison. Thus, the first comparison should be 
between the different subjects in the smaller groups, then any one 
subject with any other in the whole group. Thus A may be com- 
pared with B, C with D, then E with F, or C with E, or F, etc. A 
may then be compared with any other subject, etc. 

IV. Composition of the Tables 

Each table is composed of two series of reactions each complete 
in itself. The first series gives the reaction time without distraction, 
or the simple reaction time, and serves as a daily control for the 
second series in which the influence of the distraction was present. 

The first series is made up of 5 sets of 10 reactions each with the 
accompanying M.V., and P.E., excepting the cases noted on page 21. 
The second period is made up of 10 sets of 10 reactions each. The 
M.V. and P.E. are given for each of these averages of 10 sets. 
Thus each figure in the first series with no distraction represents 
the average of 50 reactions,^ and of 100 reactions in the second 
series with distraction. 

1 The exceptions have been stated early in the discussion. (See p. 21.) 



EFFECT OF DISTRACTION ON REACTION-TIME 35 

The date indicated in the first column denotes the time when the 
two series of reactions in the second and fifth columns were made. 
With few exceptions only one series was made in one day, but oc- 
casionally more than one series was made with distraction present. 
In this case the date is followed by one series of numbers in the 
second column, and two series in the fifth column. The single 
series served as the control test for the two series with distraction.^ 

Under "R" is given the ratio of the series of reactions with 
distraction to the series without distraction. This indicates in a 
degree the relation of the two series from day to day. If the two 
series vary in about the same degree from day to day it may be 
noted in these ratios. If the ratio is greater than 1.00 the reaction 
time with distraction was greater than the simple reaction time. 
These ratios are grouped in groups of 5 when possible and the general 
average given in the last column. The general average of each 
series is given beneath its proper series. 

V. Calculations 

1. The mean variations given under M.V. in Tables I. to XVII. 
are the mean variations of the averages of the separate sets of 10 
reactions from the day's average. Thus the variations of the aver- 
ages of all the series is shown from day to day. This method takes 
no account of the variation of single reactions in a set. A com- 
parison of the three possible methods has been made by Poffen- 
berger.^ He states that the variatioas within a series are about 
the same as those among the different series, while the variations 
of the individual reactions from the general average are about 50 
per cent, higher than either. 

2. Probable Error of the Average. — The probable error (P.E.) 
was calculated to the formula: 

P.E. = -8453 M.V. 
' ' n 

3. The Probable Error of a Difference. — (P-E.^iff.) was calculated 
according to the formula: 



P.E.ai..^-^ = aI(P.E. )2 + (P.E.^)2, 

in which P.E.^ is the probable error of the average of A by the 
preceding formula and P.E.b the same for B. Reference to page 
50 will show P.E.^, as used, to be the probable error for the 

2 The experiments were made in 1913-14. 

^ "Reaction-time to Retinal Stimulation," Archives of Psychology, 21, 
No. 1, p. 46. 



36 EFFECT OF DISTRACTION ON REACTION-TIME 

average gain in the final control test over the preliminary test for 
the practise group, and P-E.^ the same for the control group. 

4. The Relative Variability of each subject in each class of 
reactions is shown at the bottom of each of the previous tables. 
The relative variability here means the average M.V./Av., where 
M.V. is the mean variacion of the several sets of reactions taken in 
each period, and Av. is the general average of these sets. The 
figure given is the general average of these quotients for the entire 
series; it is the general average of a series of Pearson Coefficients 
of Variability. 

VI. The Distraction Effect 

To reiterate: the subjects were instructed to attend to the stimu- 
lus, react to it as quickly as possible, and give no special consider- 
ation to the distraction. This factor, no doubt, tends to lessen the 
difference between the simple reaction time and the reaction time 
with distraction. 

After instructions were given, a few preliminary trials were made, 
in which the position in space where each stimulus and each dis- 
traction would occur was emphasized. 

1. Meaning of "Distraction Ejfed." — By "effect" here is meant 
the difference in the time with distraction from the simple reaction 
time or time without the distraction. 

Distraction effect is indicated both by the tables and graphically. 

The tables of individual reactions represent only averages, that 
of pure reaction for 50, and with distraction for 100 reactions. 
These are indicated on the graph by a dotted line and a solid line 
respectively. 

A general discussion is not applicable to the six, but some facts 
may be noted i i the individual records. 

2. Discussion of Individual Records. — (a) Subjects A and B. — 
These subjects began the experiment by reacting to light with light 
distraction. A was inexperienced, B was well trained, having 
served as subject and experimenter in other reaction experiments.'* 

Subject A at the beginning had a difference between the pure 
reaction time and the time with distraction of 81.9 a, while at the 
close of 39 days of training with light distraction, the difference was 
14.8 0- in favor of the distraction reaction. If the table of ratios 
is examined, it will be found that within this training series there 
were 18 cases where the distraction did not slow the reaction but 
even facilitated it. This is about one half of the cases. We might 
conclude, in the absence of further evidence, that while light acted 
as a distraction in the beginning, the subject gradually overcame 

* B is the same as subject P in: Todd, op. cit., and Poffenberger, op. cit. 



EFFECT OF DISTRACTION ON REACTION-TIME 37 

this influence in the latter part of the series. But from an intimate 
knowledge of conditions and from the introspections of this subject, 
it is certain that these ratios do not represent the real effect of the 
distraction. In the beginning of the experiment twenty reactions 
were thought to be a sufficient number for the control on each day. 
But this was found to be too small a number, as the "warming up" 
required at least forty reactions before the minimum time of 
reaction was reached. This was very noticeable with A. He 
seemed to require considerable time to "get set" or warm up to the 
ways of the experiment.^ 

During the course of the experiment, A noted that his eyes did 
not adapt themselves readily to the dark,^ consequently typical 
reactions were not obtained, as the white disc which served as a 
location point was not always visible. This condition was never 
fully corrected though what should have been ample time'' was 
allowed for full adaptation to the dark. Then A had lost much of 
his interest in the experiment because of pressing duties away from 
the university,^ and tended to assume a passive attitude and concern 
himself with his own thoughts (as introspection revealed), the 
reaction process being nearly reflex. But when distraction was 
introduced, the change to more difficult conditions made it necessary, 
in order to make a creditable reaction at all, to give more attention 
to the stimulus and the movement. Thus the time would be 
shortened by the distraction. Note the similar effect of the dis- 
traction after practise on E and F. (See pp. 45 and 78.) 

When sound distraction was introduced in the second series 
the disturbance due to poor adaptation to the dark was eliminated, 
and at this time A was also relieved from over-pressure of work. 
The distraction effect is seen in all cases but one. But it is not 
safe to conclude that sound is necessarily a better distraction than 
light; for it seems rather that the effort required to make a reaction 
was not so great with sound as with light distraction. 

From ^'s results we may conclude (1) that light, sound, and 
touch distractions all affected the reaction time; (2) that there was 
a very noticeable decrease in the influence of light as a distraction 

^ As the first series was taken to a stimulus without distraction, this lack of 
quick adjustment cannot be attributed to the distraction. It was a purely per- 
sonal characteristic. 

8 Wells, Psychol. Rev. Mon. 15, No. 5, p. 40. 

^ For complete adjustment to dark about 20 minutes are required but as the 
room was dimly lighted so much time was hardly necessary. The time necessary 
seems to be a matter of individual differences. 

8 The fact that this period was preceded by nearly four thousand reactions 
may have influenced this change in attitude. Over-training and a "stale" 
condition may have aroused this attitude. 



38 EFFECT OF DISTRACTION ON REACTION-TIME 

due to the long period of practise and the personal characteristics 
of the subject, his change in attitude, over-training, staleness, or 
failure to observe instructions. 

Subject B had the same training as A, though he was an experi- 
enced subject. The reaction time was shorter with distraction than 
without ic in about a sixth of the cases when light was the dis- 
traction, in about half of the cases with sound distraction, but never 
when touch was the distraction, in spite of all the previous training 
with the other two distractions. 

A few notes from the introspections and observations of this 
subject reveal a typical condition. When the records from which 
the ratio .99 was derived were made (Feb. 28), he reported that 
while making the simple reactions to light he was in a state of 
complete confusion. He seemed to have no idea just when the 
stimulus would appear. "The stimulus was there, then I had to 
get ready and react." During the course of the experiment he 
adjusted himself, though he still reacted with effort when light dis- 
traction was applied. After a rest of about ten minutes, the second 
series was made, in which the ratio was 1.08. 

It seems that B, because of his previous experience, reached his 
physiological limit toward the end of the series of reactions to light 
with light distraction. A, not a practised subject, continued to 
improve, and was spurred on to do better and better, though, 
after a time, his simple reactions tend to become mechanical and 
not to show further progress. But the novelty of the distraction 
experiment broke up this tendency to automatism and even led to 
further improvement in the simple reaction time (see the gen. aver, 
of the last two series for A). 

B, on the other hand, being near his physiological limit, was 
necessarily disturbed by the novel conditions of distraction. When 
touch distraction was introduced, however, there was a further 
increase of the simple reaction time of both A and B. 

(b) Subjects C and D had both had some experience in reacting, D 
more than C. Both became adjusted quickly and easily to the 
experimental conditions. The distraction effect is very noticeable, 
but is overcome to some extent as training progresses. (For subject 
D, the ratio of 1.27 on February 12 is not characteristic. The simple 
reaction time was very low, the distraction time very high, hence the 
high ratio. The record of the previous day is 1.04.) 

Cs reactions are remarkably uniform, although the distractions 
were effective when first introduced. The distractions did not 
cause any decided "set-back" in the reactions. The figures for the 
"relative variability" show the effect of practise in their gradual 
decrease. 



EFFECT OF DISTRACTION ON REACTION-TIME 39 

(c) Subjects E and F had a slightly different training from the 
other subjects. Before any distraction was introduced, there was a 
period of practise in reacting to sound without distraction. This 
practise was continued till the physiological limit was apparently 
reached. This period of training should eliminate the practise 
effect, and make the subjects familiar with all the details of the 
experiment. Any changes noted in later periods when distraction 
is introduced will probably be due to the influence of the distraction. 

At the close of this first training period subjects E and F began 
reacting to the same sound stimulus as before, but with sound dis- 
traction present. The distraction was later changed to light, and 
finally to touch. Thus the order from the close of the first training 
period was identical with that of C and D. 

There are several cases in E's records in which the "ratio" sinks 
below 1.00, and in which, accordingly, the distraction had apparently 
a facilitating effect. Regarding these, however, the following re- 
marks are in order: 

On March 9, with sound distraction, the ratios 1.01 and .96 
were obtained in two successive series. The subject remarked that 
he noticed the distraction more and more as the series progressed 
but was not greatly confused by it. 

On March 17, with light distraction, the ratio of .98 would become 
1.04 if the first set of simple reactions, with the high average time 
of 137.0 (T, were eliminated from the control record. If this correc- 
tion were made, the following ratio of 1.04, made on the same day, 
would rise to 1.09. 

On March 21 and 22 occur four ratios less than 1.00. They 
would be raised above 1.00 if the control average were taken from 
the last set of 10 simple reactions before distraction was introduced, 
instead of from the whole series of 50 simple reactions made at the 
beginning of the day's experiment. Though this method of deter- 
mining the control average has not been adopted, it could be 
defended on the ground that it represented best the simple reaction 
time for the day after warming-up had occurred. 

On March 22, with touch distraction, occur four ratios less than 
1.00. Here it is to be remarked that, owing to unavoidable cir- 
cumstances, several series were made on one day, and with but a 
single control series. The distraction series show considerable 
improvement throughout the day's work, and probably the simple 
reaction would have showed a like improvement, and the ratio 
thus maintained at about the level that it had at the beginning of 
the day's work (1.06 and 1.02). 

The record of subject F also shows several low ratios. The ratio 
.95 with sound distraction (March 19) is not to be treated too 



40 EFFECT OF DISTRACTION ON REACTION-TIME 

seriously, although the P.E. is but .8 a. The record following 
was made the same day and is a better representation of normal 
conditions. In the first case the distraction was felt as a very 
strong factor and the subject tried hard to overcome this, but in 
doing so made nine premature reactions. In the second case these 
did not occur. 

With light distraction the ratio .99 on March 20 is due to one 
long set of simple reactions occurring in the control series, without 
which the ratio would be 1.02. On March 24, the ratio .96 occurs 
twice. The simple reaction time was very long on this day, 121.4 <r, 
P.E. 2.0 0-. The subject stated that at the beginning of the day's 
experiment he could not keep from thinking of irrelevant things; 
but distraction helped to keep his mind from wandering. The ratio 
.97 on March 25 is probably due to the tendency to premature 
reactions, five of which occurred. Though the premature reactions 
did not enter into the averages, the fact that the S even took a 
chance occasionally might tend to shorten the time. 

These erroneous reactions may operate in one of two ways; 
some persons shorten the average reaction time by taking the chance 
of incurring some errors, and others are hampered by the occurrence 
of an error, become over-cautious and lose time in hesitation. Thus 
premature reactions may signify a gain to some and a loss to others.^ 
Subjects E and F had shorter reaction time when premature reac- 
tions occurred, but subject A was much disturbed by them. Most 
of this tendency to premature or synchronous reactions occurred 
when the distraction was present, and with subjects of the motor 
type of reacting. 

It is well to note that neither E nor F was working at maximum 
capacity while reacting to sound alone. Very soon after the sound 
distraction was introduced, the time of reacting to sound decreased 
materially and continued throughout on this lower level. 

3. General Statement. — The tables for subjects A, B, C, D, E 
and F show series of reactions with and without the distraction 
from day to day, and also the general average of each of the series. 
Reference to these averages will show the general effectiveness of 
the distractions used. That the distractions were true distractions 
can not be doubted. But few exceptions occurred where this was 
not true. Some of these cases were evidently due to chance; others 
to definitely known causes. 

The effectiveness of the light distraction with the stimulus light 
is partially hidden in the case of subject A. This was partially 
due to the erratic nature of the subject and his inability to make 
quick adjustment to experimental conditions. His period of ad- 

' Seashore, Iowa Studies in Psychol., 1899, 2, 67. 



EFFECT OF DISTRACTION ON REACTION-TIME 41 

justment occasionally extended throughout the entire control 
period. Thus the control test would be too high and as a result the 
effect of the distraction in the second series would be lost. This 
may have been the case with subject B in the series with sound as a 
distraction. B indicated that he did not react well in the beginning 
of some series but did not known the reason for it. 

Subjects E and F may have failed at certain times to follow 
instructions carefully. Both noted an occasional tendency to react 
prematurely. It is possible that the distraction may have served 
unawares as a sort of preparatory signal. These conditions were 
not general, but probably occurred just frequent enough to narrow 
the margin between the control and the distraction series. 

^Introspectively, all the subjects felt a decided feeling of strain 
and annoyance when distraction was introduced. Any tendency 
to make a mechanical or reflex reaction was prevented, at least 
temporarily. This was the strongest influence of the distraction 
which the subjects noticed. As soon as the distraction was intro- 
duced the subject felt confused. There seemed to be no opportunity 
to establish any definite order, or rhythm. The distraction and 
stimulus were not confused, but the time of the stimulus could not 
be anticipated. Amid the confusion the stimulus appeared and 
the subject then had to react. But this, of course, is the influence 
which we attribute to any distraction. Just as soon as the extra- 
neous stimuli fall into a more or less definite order or sequence 
they cease to distract us. 

4. Effect of Practice on the Distraction. — Practice lessened the 
influence of the distraction, but never wholly overcome it. Ref- 
erence to the curves 3 to 8 constructed from the data of Tables 
I. to XVII. will show the rapidity with which the subjects lessened 
the influence of the distraction. Some subjects required more 
practise than others to reach a similar proficiency in ignoring the 
distraction. The distraction had the greatest influence at the 
beginning of practise, with the first series. With practise this 
influence waned very rapidly till 800 to 1,000 reactions had been 
made, after which further practice had very little effect on the in- 
fluence of the distraction. 

The figures show that practise influenced both the series without 
distraction and the series with distraction but the effect was much 
more noticeable at the beginning of the latter series than of the 
former. However, after this initial period of rapid improvement 
the effect was similar in the two series. 

5. Effect of Practise on Trained Subjects. — To determine more 
definitely the effect of the distraction from the very time when it 
was introduced, two subjects, E and F, were given practise in 



42 EFFECT OF DISTRACTION ON REACTION-TIME 

reacting to a sound stimulus without the distraction. Adaptation 
to experimental conditions would thus occur within this first prac- 
tise period, and, when the distraction is introduced what change 
occurs must be attributed to the distraction. 

After E and F had reacted to the sound stimulus till no further 
gain seemed possible, the sound distraction was introduced. After 
practise with this distraction, the Hght distraction was introduced, 
and later, the touch distraction was used. Hence, there is a series 
of simple reactions to sound, a series of reactions to sound with 
sound distraction, a series to sound with light distraction, and a 
series to sound with a touch distraction. These last three series 
are also accompanied by a series of simple reactions for a daily 
control series. See Tables XL to XVII. and figs. 7 and 8. 

So far as type of reacting is concerned here, E and F were very 
similar individuals. Both were more or less erratic at certain 
periods during the experiment. 

In the first practise period adjustment to the experimental 
conditions occurred quite rapidly, and although the adaptation is 
not uniform, both subjects apparently reached a limit before the 
series was closed. 

When the first distraction was introduced a peculiar change 
was noted. Practise not only reduced the reaction time with the 
distraction, but the control series with no distraction was further 
reduced. This may be a true practise effect, but it seems more 
likely that the careful attention and intense effort necessary to 
react with the distraction present became a permanent asset and 
thus aided in improving the other reactions. This would indicate 
that the subjects had not been working at their maximum ability. 
When the distraction was introduced a change in attitude occurred 
and henceforth the work was performed on a higher plane of 
efiiciency. 

When distraction was introduced, the distracting effect was not 
so great with subject F as with subjects A, B, C, and D. The 
variations were not so great for E and F as for the other subjects. 
Otherwise, E does not seem to have gained from his practise period 
without distraction. The same general practise effect occurred 
within his first 1,000 reactions as was noticed with A, B, C, and D. 
This was not true of F. He had ehminated this period by his 
previous practice. A, B, C, and D had to accustom themselves to 
experimental conditions, and also to withstand the influence of the 
distraction. E and F had these factors singly to contend with. 
For this reason much of the great variability in the early part of the 
practise period is ehminated. The distraction effect seems to be 



EFFECT OF DISTRACTION ON REACTION-TIME 43 

greater with an unpractised than with a practised performance, 
though this point needs further investigation. 

VII. The "Warming-up" Period 

The "warming up" or incitement period seems fairly charac- 
teristic of the work curve of most individuals but Thorndike be- 
Heves that its importance is commonly exaggerated.^'' The period 
is usually short and occupies only the first few minutes of the ex- 
periment. 

In the present experiment the warming up period was char- 
acteristic of the simple reactions and present to a less degree in the 
reactions with distractions. (See Tables XIX. to XXV. and curve 

The very first part of the work would suggest an initial spurt. 
The subjects decreased gradually in efficiency in reacting during the 
first few minutes then seemed to recover and gradually improve 
to the end of the period. When distraction was introduced this 
same type of reacting was present in a less marked degree. 

This "warming-up" period was not uniform with the different 
subjects in the amount of time required. This irregularity of 
adjustment to experimental conditions in the simple reactions has 
probably hidden some of the real influence of the distraction in the 
second series. It will be remembered that fifty simple reactions 
were taken at each period as a daily control. The distraction was 
then introduced, the stimulus remaining the same, and one hundred 
reactions taken. If the subject failed to get "well set" in the 
experiment until about the end of the simple reaction series the 
average of these fifty reactions would necessarily be higher than the 
normal reaction time. By the time distraction was introduced, the 
subject would be fairly well adapted, so that his reactions would be 
influenced by nothing but the distractions, but how much this 
influence amounted to could not always be shown, as the simple 
reactions were unduly influenced by the warming-up period. A 
great number of reactions, however, will tend to eliminate some of 
this influence. 

Some experimenters have followed a definite method in elimin- 
ating reactions which seem affected, or discordant, by observing 

i« "Educ. Psychol.," III., 67. 

"The time required for "warming up" and adaptation depends upon the 
individual, and varies from day to day. Usually, a long "warming up" period 
may be associated with the individual who cannot eliminate extraneous influ- 
ences from the experiment. Often these influences are nothing more than his 
own thoughts. 



44 EFFECT OF DISTRACTION ON REACTION-TIME 

the variability in each case. Cattell and Dolley^^ state their method 
as follows: "In each series we made thirteen reactions, and rejected 
the time which departed most from the mean, then the time which 
departed from the mean of the remaining twelve reactions, and 
finally the third most discordant reaction. We thus had the mean 
of the ten most accordant reactions, which would represent a com- 
promise between the median and the mean." 

Holman rejected the supposed mistake if its deviation was 
greater than four times the average deviation of the other measure- 
ments.^^ 

Since it was the effect of the distraction which we were attempt- 
ing to measure, all reactions were recorded, and only those were 
eliminated which the experimenter knew were wrong or which were 
reported as wrong by the subject. Only a few were eliriiinated and 
these omissions are indicated in the tables. 

VIII. Temporary Adaptation to the Stimulus 

Tables XIX. to XXV. give the average daily performance 
throughout the series both with and without distraction. Fig. 9 
is based on these tables. The short "warming-up" period was 
characteristic of each set of daily reactions both in the control set 
of fifty reactions and in the one hundred reactions with distraction 
present. This period of adaptation was much more noticeable in 
the beginning of the experiment than near the end. The adaptation 
was much slower in the daily control test than with distraction 
present. There are two reasons for this: (1) The adaptation in the 
first series prepared the subjects fairly well for all the work which 
followed. (2) Reacting with the distraction present required a 
better type of attention. The subjects found that more effort was 
required and so gave more attention to the work. This factor 
coupled with the desire of the subject to succeed as well as when no 
distraction was used caused a very rapid adjustment in the series 
with distraction. 

1. Daily Work Curve. — Further evidence of the disturbing effect 
of the distraction was found within the daily work curve. These 
curves seem typical of the kind of work performed. There is also 
a great similarity among the individuals who had the same special 
training.^^ 

1^ Op. cit., p. 402. Poffenberger began his computations by using this same 
method but found that the corrections made but little difference in the results. 
Op. cit., p. 43. 

1^ "Discussion of the Precision of Measurements," N. Y., 1892, p. 30; Bliss, 
Yale Studies, 1892-3, 1, 18. 

^* The data of which the curve is a graphic representation appear in Tables 



EFFECT OF DISTRACTION ON REACTION-TIME 



45 



These curves indicate at a glance whether the distraction func- 
tioned most as a disturbance in the beginning of the day's series, 
at the close, or was general throughout the period. 



loo 



J90 



d 

2. 
WO 



V 



^r>L 












\ 


y^ 












v/^ 


<^r 










> 


1 


V-^ 








>-^ 


. 






















Fig. 9. Graphic representation of Tables XIX to XXV. 

In the reaction time without distraction there was present in 
most cases a general "warming-up" at the beginning of each series. ^^ 
When the distraction was introduced, the reactions were lengthened, 
but in the second set of 10 there was partial recovery. From this 

XIX. to XXV. Each point on the curve is an average of the averages of the ten 
reactions made at a given part of the sitting. Column one represents the average 
of the first set of ten in all the sittings. Column two, the average of the second 
set, etc. In brief, the curve is a composite daily work curve. Reference to Table 
XVIII. will make this formation clear. 

^* Cattell observed that the first reactions of a series are the shortest. It 
seems that in the first experiments the observer involuntarily strains his attention 
more and so gives shorter times. This is more marked the less automatic the 
process is. Mind, 1886, 11, 537. 

4 



46 EFFECT OF DISTRACTION ON REACTION-TIME 

point there was a gradual slowing of the reactions, most noticeable 
with A and B and least with D and F. 

The clearest representation of the distraction may be had by 
observing the last point in the first curve and the first and last 
points in the second curve for each subject (Fig. 9). In every case, 
without exception, the points in the last curve are widely separated 
from the last point of the first curve, and in most cases from the 
first point. 

There was no evidence to show that the waves or irregularities 
in the curves were due to any particular physical cause. Indeed, 
irregularities would be expected since the product of the nervous 
system is a variable quantity. If these curves approached a straight 
line, an explanation would be demanded. 

The gradual increase in the reaction-time throughout the sitting 
may suggest fatigue, but it is difficult to believe that fatigue played a 
part in so short a time as that required to make one hundred and 
fifty reactions, interspersed with frequent rest periods of about ten 
seconds each. The fifteen sets (five to simple stimulus and ten to 
stimulus with a distraction, 150 reactions in all) never required 
more than twenty-five minutes including the rest period of about 
ten minutes. Usually less time was required. It is doubtful if 
any marked tendency toward fatigue would occur within this 
short period with so reflex an act as the reaction tends to become in 
practised subjects. CattelP^ found that the effect of fatigue was 
slight even when reacting almost continuously (15-20 hours) 
throughout the whole day. Bettmann found^^ that in making 
choice reactions for about two hours, in which two thousand re- 
actions were made, the reaction time was increased only about 25 a. 
Poffenberger and Todd reacted almost continually for two hours 
or more to rapidly appearing stimuli. They found the effects of 
fatigue absent or very slight. 

If an increase in the variability is indicative of fatigue,^^ it is 
impossible to infer fatigue from the observed variations, which 
show a somewhat general decrease from the beginning, due to the 
practise effect, and no other general tendency. It is not proper 
to treat the occasional high deviations which occur in some records 
as evidence of fatigue. These, no doubt, are due to chance. The 
subject is not well adapted, he is more easily disturbed than on 
other occasions, he has changed his attitude, or has hit upon some 
little device, or is deeper in the old rut at this special time when the 
high variability occurred. The elements of the so-called mental 

i6Mwd, 1886, 11, 536-537; Wundt's Phil. Studien, 1886, 3, 489-492. 

1^ Kraepelin's Arbeiten, 1, 156. 

isThorndike, "Educ. Psychol.," 3, p. 11, 12, 1914. 



EFFECT OF DISTRACTION ON REACTION-TIME 47 

and general fatigue in ordinary life seem to be inability to attend, 
headache and sleepiness, but headaches seem more frequently a 
result of mental, and sleepiness of muscular work. At the close of 
each sitting, the subject reported his type of attention and his 
physical condition, rating each as excellent, fair, or poor. In so 
far as these remarks may be taken as indicative of conditions, no 
fatigue was noted. Some subjects even reported that their con- 
dition had improved during the experiment, although the reaction 
times had increased in length. No one reported that attention 
could not be given to the experiment. When light was the dis- 
traction, the subjects occasionally reported a sensation of sleepiness, 
a partial hypnotic state. If we must consider feelings of annoyance 
and of desire to stop the experiment as indicative of fatigue, then 
fatigue was undoubtedly present, as it would be in any task pur- 
sued for any noteworthy length of time. The retrospections in- 
dicate that fatigue, as usually understood, was not present. 

In prolonged exercise of any function, the two opposing elements 
of practise and fatigue enter. In this experiment the effect of 
practise was minimized by the fact that some of the subjects were 
previously trained, while all received a long period of training at 
the beginning of the experiment. It also seems safe to conclude 
that fatigue was not present enough to influence the time of reacting 
to a noticeable extent. What change did occur in the course of a 
sitting must accordingly be due to the influence of the distraction. 

2. Tables XIX. to XXV. give a composite summary of the 
work of the different practise subjects. The data were derived from 
tables similar to Table XVIII. for C. Each sitting began with five 
sets of 10 reactions without distraction. The averages of these 
sets are shown in the first five columns. The subjects then made 
ten sets of 10 reactions to the same stimulus as before but with a 
distraction present. The averages of these sets are shown in the 
last 10 columns. The average at the top of the table represents 
the general average for all the single sittings, the number of which 
is shown in the parenthesis; e. g., 35 in parenthesis means 35 sets of 
10 reactions each, or a total of 350 reactions. The first set of 
figures beneath the average is the M.V.; the second set the P.E. 
The general average at the bottom of the table is obtained, not from 
the single sittings directly, but from the three averages made with 
the three different distractions. Much of the variability has been 
eliminated from this latter group as it is not so weighted as the other 
averages. For this reason it probably throws the weight of evi- 
dence where it naturally belongs. The first general averages, 
however, were used in all the comparisons. The second, third, and 



48 EFFECT OF DISTRACTION ON REACTION-TIME 

fourth lines represent the averages of the reactions without and with 
the special distraction. 

E and F had a period of training in making simple reactions to 
sound. These were made in sets of 10 reactions each. The average 
of these sets is given in Table XXV. No reactions with distrac- 
tion were made during this training. The results of Tables XIX. 
to XXIV. are summarized in Table XXVI, only the general aver- 
ages of the individual sets being here given, with the M.V. of cor- 
reponding sets, the P.E. for the average values of the sets, and the 
number of sets going to make up the averages, in the three lines 
below. (See Table XXVI, p. 88.) 

TABLE XXV. 

Average Simple Reaction Time to Sound for Successive Sets of Ten 

Reactions 











Subject E 










133.5 


136.6 


134.5 


128.9 


130.9 133.4 


131.7 


130.9 


135.3 


128.3 


6.1 


9.8 


9.8 


8.4 


7.2 6.8 


4.9 


9.8 


5.5 


6.8 


i4 


2.2 


2.2 


1.9 


1.6 1.6 


1.3 


2.5 


1.4 


1.7 


(13) 


(13) 


(13) 


(13) 


(13) (12) 
Subject F 


(10) 


(10) 


(10) 


(10) 


13^.1 


133.9 


134.1 


131.1 


133.1 134.1 


131.1 


134.8 


134.9 


132.5 


9.1 


9.7 


11.3 


9.3 


11.8 11.5 


10.5 


11.1 


12.9 


10.3 


1.6 


1.7 


2.1 


1.7 


2.2 2.2 


2.0 


2.1 


2.4 


1.9 


(21) 


(21) 


(21) 


(20) 


(20) (20) 


(20) 


(20) 


(20) 


(20) 



3. To show the effect of practise and distraction in a rough way, 
the series of one hundred reactions made each day during the ex- 
periment has been divided and the average of each half determined. 
This has also been done for the fifty reactions used as a daily control 
and taken just previously to the introduction of the distraction. 
Table XXVII. shows this comparison. 

TABLE XXVII. 





Gen. Av. 


of Train- 


Gen. Av. 


of the 


Gen. Av. 


of Series 




ing Series with 


Control Series 


with Distraction 




Sound 










Subj. 


1st half 


2d half 


1st half 


2d half 


1st half 


2d half 


A 






227.20- 


213.0O- 


222.4(7 


222.7(7 


B 






205.4 


202.1 


210.3 


214.1 


C 






123.2 


121.9 


123.3 


122.6 


D 






129.9 


125.8 


149.3 


141.5 


E 


...132.0 


131.0 


125.3 


117.9 


124.1 


124.5 


F 


...131.2 


155.0 


116.8 


114.4 


121.1 


120.6 



EFFECT OF DISTRACTION ON REACTION-TIME 49 

E and F had a period of practise in reacting to a sound stimulus 
without the distraction. This practise series was followed by the 
same training that C and D received. The first two sets of figures 
are the averages of the first and second halves of this series without 
the distraction. 

The subjects improve within the sitting quite rapidly making 
simple reactions, but when the distraction enters the improvement 
is not so marked; in fact, the influence of the distraction is felt as 
much in the second half of the period as in the first half. The table 
also shows that fatigue was not a strong factor. 

IX. The Most Effective Distraction 

It is impossible to make a dogmatic statement here as we must 
consider the distraction effect from more than one point of view. 
The "most effective distraction" may mean that which affected 
the reaction-time by the greatest amount, or that which affected 
it for the longest period, i. e., which was most difficult to overcome. 

1. If we take the average excess time of the series with dis- 
traction over the series with no distraction (the daily control series) 
for all the subjects in the practise group, we have the following, the 
greatest difference indicating the greatest distraction effect. 

Sound Light Touch 

14.9(7 13.80- 7.80- 

From the above may be noted the similarity of sound and light 
as distractions. Touch seems inferior if amount of effect is con- 
sidered. But it should be remembered that touch was the last 
distraction used, and that, for this reason, the subjects were better 
trained when they began the touch series than with fight and sound. 

2. If the first part of each series with light and sound distraction 
is omitted in the practise of A and B, and C and D a better compari- 
son seems possible. This order is as follows: 

Sound Tov^h Light 

12.5cr 7.8(r 5.3a 

As the longest reactions occurred with A and B in the very be- 
ginning when light was the distraction, the elimination of these 
accounts for the shift of light to the end of the above series. 

So far as amount of difference is the criterion for determining 
the most effective distraction, sound is first, light second, and touch 
last. But this is a gross comparison and must not decide the 
question. 



50 EFFECT OF DISTRACTION ON REACTION-TIME 

3. The general average of the ratios or relation of the distraction 
series to the series without distraction gives another comparison 
(see Tables I. to XVII.)- Thus we have the following: 

TABLE XXVIII 

Stimulus, Light 

Distraction 

Sound Light Touch 

A 1.01 1.00 1.06 

B 1.00 1.06 1.04 

Gen. Av 1.01 1.03 1.05 

Stimulus, Sound 

C 1.15 1.13 1.08 

D 1.14 

E 1.12 1.01 1.01 

F 1.07 1.01 1.04 

Gen. Av 1.12 1.05 1.04 

By this comparison, little difference appears between the specific 
effects of the three distractions. 

4. The variability of the reaction time in the preliminary and 
final control tests for the two groups of subjects may be an index 
of the amount of distraction. Higher variability probably indi- 
cates more distraction effect (see p. 69). The table below shows 
such a comparison. 

TABLE XXIX 
Practise Group 

Distraction 

Light Sound Touch 

Prelim. Test 077 .055 .039 

Final Test 046 .051 .044 

Control Group 

Prelim. Test 065 .067 .071 

Final Test 055 .042 .048 

5. The results below are the average excess of the reaction time 
with distraction over the time without the distraction in the pre- 
liminary and final control series. 

TABLE XXX 

Control Group 

Sound Light Touch 

Prelim. Test SB.Oa 22 Aa- 21.5ff 

Final Test 34.9 26.0 17.6 

Gen. Av 33.9 24.2 19.5 

A.D 10.0 1.8 2.0 

P.E 0.6 1.1 1.2 



EFFECT OF DISTRACTION ON REACTION-TIME 51 

Practise Group 

Light Touch Sound 

Prelim. Test 29.2<r 2o.8(r 25.7a 

Final Test 13.0 16.4 10.9 

Gen. Av 21.1 21.1 18.3 

A.D 8.1 4.7 7.4 

P.E 4.7 2.7 4.3 

6. The distraction which worked most frequently, though the 
effect was small, is in a sense the most effective distraction. The 
evidence on this point is not uniform, but, a decided distraction 
was caused in the following percentage of cases: 

Sound, 89 per cent.; Touch, 82 per cent.; Light, 64 per cent. 

7. According to the introspections of the subjects (not offered 
as conclusive proof) the distractions were effective in the following 
order : 

Sound, Light, Touch. 

The subjects were soon able to ignore entirely the touch dis- 
traction (although the reactions showed that it was still effective), 
but this was not true with the sound distraction, and the subjects 
felt most of the time that the sound was actually "beating in" on 
them. 

Conclusion. — It seems warranted from these last comparisons, 
although the differences are small, to state in conclusion that sound 
was most effective as a distraction. The author does not wish to 
include the first comparisons in this statement, as they are very 
general. 

Swift obtained somewhat different results from the above, 
perhaps because of a difference in the disturbance used, which in 
his case was intermittent and appeared one hundred and twenty 
times per minute. "When the disturbance and excitation affect 
the same sense, a distraction of the attention through the sense of 
sight has more influence upon the reaction-time than the same grade 
of a disturbance through the sense of hearing. "^^ 

The strong distraction effect of sound — if we may accept it as 
proven — may be related to several other facts: the quick reaction 
to sound, the special liability to false reactions to intercurrent sound 
stimuli,2o the reflex start which is evoked by sudden noises, and the 
poor localization of sounds. The distracting influence of sound 
may operate primarily at the reflex level. The nervous mechanism 
for reactions to the sense of hearing, as to the sense of touch, has been 
primarily a protective mechanism. Though we tend to think of 

" Amer. Jour. Psychol, 1892-3, 5, 12-15. 

20 Bliss, "Reaction-time and Attention," Yale Studies in Psychol, 1, 39. 



52 EFFECT OF DISTRACTION ON REACTION-TIME 

touch as the chief protective sense, hearing, phylogenetically more 
recent, has perhaps taken its place as the chief means of protection. 
Sight, typically, informs us of danger from which there is ample 
time to escape, and touch of danger from which, if it is serious, we 
can scarcely escape by simple protective reactions, while hearing 
tells us of dangers from which escape is possible by quick reaction. 
The heard danger is near and demands promptness, and by natural 
selection a short and direct neural path for reactions to sound has 
been established. Sudden sound stimuli therefore act on us with a 
compelling force and can not be easily disregarded. 

But, more than this, whereas localization of visual and tactile 
stimuli is prompt and precise, and the instinctive reaction to them 
correspondingly locahzed, sounds are more slowly and vaguely 
localized, and the first reaction to a sudden sound is a "start," 
which bears no relation to the source of the sound, except that the 
sound is reacted to as if near. Sound raises a problem of localization 
which does not immediately resolve itself; and, hence, perhaps, its 
hold on us and its strong distracting effect. 

X. Is THE Distraction More Effective when Belonging to 

THE Same Sense as the Stimulus or to Another 

Sense? 

By using the average of the ratios in Tables I. to XVII. the 
following comparison may be made. 

TABLE XXXI 

Same Sense 
Subject Stimulus Distraction 

A,B Light Light 

C,D,E,F Sound Sound 

Av. 

Different Sense. 

A, B Light Sound 

" " Touch 

C,D,E,F Sound Light 

" Touch 

Av. 



A comparison with touch can not be made, as a series for touch 
was not made. But even if we eliminate the touch distraction from 
this experiment the comparison remains unchanged. 



1.04 






1.12 






1.08. 


A.D. 


.040 




P.E. 


.024 


1.01 






1.05 






1.02 






1.04 






1.03 


A.D. 


.015 




P.E. 


.006 



EFFECT OF DISTRACTION ON REACTION-TIME 53 

The comparison indicates that the distraction is more effective 
when belonging to the same sense as the stimulus.^^ Of the dis- 
tractions not belonging to the same sense as the stimulus, touch 
seems the most effective. 

When the stimulus and the distraction both belong to the same 
sense there is always some similarity between the two, and thus a 
slight discriminatory tendency probably arises. This is especially 
true with sound which is very distracting, due to the inability of the 
ear to localize sounds definitely. Locahzation in the case of light 
and touch, if needed, are more accurate. 

XI. Conclusion 

1. All the distractions affected the reactions by making the time 
longer. 

2. The period of greatest distraction occurred at the beginning 
of the series. Light distraction caused the greatest distraction at 
the beginning, but its influence waned rapidly. 

3. Practise caused an early period of rapid adaptation to the 
distraction. This was followed by a period of much slower adap- 
tation. 

4. The effect of distraction was never completely overcome. 

5. The first practise period reduced the time of the other series 
of reactions about 50 per cent. 

6. The distraction lengthened the time of reaction of both 
trained and untrained subjects. 

7. A period of adaptation was noticeable in the daily work in the 
series with no distraction, and in the series with distraction. 

8. The relative variability of reaction with no distraction is 
smaller than the reaction with distraction (see p. 69). 

9. The distraction effect not only influences the reaction time 
with distraction but also the series of reactions without distraction. 

10. Sound was on the whole a somewhat more effective dis- 
tractioa than light or touch. 

11. The distraction effect was greater when the distraction and 
main stimuli belonged to the same sense than when to different 
senses. 

21 Earlier investigation has seemed to indicate that the reactions are more 
influenced through a disturbance of the attention if the excitation and disturbance 
affect different senses than when both are of the same nature, but this experiment 
does not sustain tliis view. — Swift, "Distraction of the Attention," A7ner, Jour. 
Psychol, 1892-3, 5, 14-15. 



CHAPTER VI 
TRANSFER OF TRAINING 

In educational discussions of ''formal discipline," as well as in 
psychological discussions of the experiments on "transfer," the 
conception of training the attention has often been introduced; but 
there has been little if any direct experimentation on transfer as 
related to training of the attention. Now since attention consists 
partly in resistance to distraction, training in resisting a specific 
distraction constitutes a specific training of attentioa, and the 
transfer effect can be examined when other distractions are sub- 
stituted for the one employed in the training.^ 

I. Experimental Procedure 

Six subjects, as described in the previous chapters, went through 
an extensive course of training in reactions to light or sound stimuli, 
both with and without certain distractions. Before and after this 
training, these six subjects {A, B, C, D, E, F), and also a control 
squad of five (F, W, X, Y, Z), were tested in reacting to light, 
sound and touch stimuli, with and without distractions. Com- 
parisons designed to show the effects of specific training can be 
made (a) between the practise and control groups, (b) between 
different subjects belonging to the practise group, since A and B 
were trained with light, and C, D, E and F with sound as a stimulus, 
and (c) between the initial performance of each of the trained 
subjects, and his performance on shifting to a modification of the 
experiment after he had received some part of his special training. 

The instructions throughout required the subject to react as 
quickly as possible, and give special attention to anything except the 
designated stimulus. These simple directions were emphasized 
enough to make them a sort of ideal. 

In the preliminary and final tests, the same stimuli with the 
same accompanying distractions were presented to the subjects in 
both the practise and the control groups in the same identical 
sequence. (See p. 34 for the order of procedure.) Approximately 

^ The recent survey of the Uterature of transfer by Thorndike in his "Edu- 
cational Psychology," 1913, Vol. II, pp. 350-443, makes it unnecessary to insert 
a historical note on the subject. See also a still more recent, brief survey by 
Martin, in his "Transfer Effects of Practise in Cancellation Tests," Archives of 
Psychology, No. 32, 1915. 

54 



TRANSFER OF TRAINING 55 

one hour each was required for the preHminary and final tests, 
including the rests which were interposed after each of the series of 
reactions. So far as introspections reveal, no fatigue was present, 
and the attitude of all the subjects was excellent. 

II. Results of the Preliminary and Final Tests 

Tables XXXII. to XLII. give the achievement of the control 
and practise groups in the preliminary and final tests. Each 
entry represents the average of fifty reactions. Under ''P.C." 
is given the Pearson coefficient of variability. The "Gain or Loss" 
includes two items. The first column gives the gain or loss made 
by the subject in reacting. Gain here means a decrease in reaction- 
time. No sign is used when a gain is made. A negative sign in- 
dicates a longer reaction-time in the final test than in the pre- 
liminary test. The last column gives the difference in variability 
between the two tests. 

Figs. 10 to 20 give a graphic representation of Tables XXXII. to 
XLII. The unshaded part represents the achievement made by 
the subjects in the preliminary test; the shaded area the achieve- 
ment made in the final control test. Between the two control 
tests A, B, C, D, E, and F had a period of practise, the data for 
which are given in Tables I. to XVII. 

Tables XLIII. and XLIV. represent the gain or loss made by 
the practise group and the control group. The first set of figures 
is the gain or loss made in the reaction time. The second set is the 
increase or decrease in the variability (M.V.). When, occasionally, 
two figures are given for the same item, the second is the reaction- 
time which followed just after the reaction from which the first 
difference was obtained. 

To obtain the average gain for the whole group the gains for the 
individuals were added algebraically. A negative sign indicates a 
longer reaction-time in the final test than in the preliminary test. 
A summary of the average gain or loss is given under its proper 
heading. The M.V. accompanies each average. 

III. Training in Simple Reaction to one Stimulus Shortens 
the Simple Reaction to Another Stimulus 

The gain showTi by the practise group in simple reaction to that 
stimulus with which they had been trained is here brought into 
comparison with their gain in reacting to another stimulus, and also 
with the gain (or loss) of the control group. 

The upper half of Table XLV. shows the gain made by the sub- 



56 



EFFECT OF DISTRACTION ON REACTION-TIME 



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TRANSFER OF TRAINING 



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58 EFFECT OF DISTRACTION ON REACTION-TIME 

jects in reacting to a stimulus through practise. The lower half 
of the table shows the gain made in reacting to a different stimulus 
as a result of the practise in reacting to the first stimulus. The 
subjects are divided into two groups according to the stimulus used. 
Under "Diff. in time" is given the difference between the pre- 
liminary test and the final control test. The last column indicates 
the difference in variability between the two series. A positive 
sign indicates that the series in the final control test were shorter 
than the series in the preliminary test. This is a gain. A negative 
sign indicates the opposite condition. 

TABLE XLV 

Practise group 
Subject Gain in Time Gain in Var. 

I, Special Training 
Gain by reacting to light with no distraction. Subjects received practise in reacting 

to light 

A +48.1<T +14.80- 

B + 5.5 -11.4 

Gain by reading to sound with no distraction. Subjects received practise in reacting 

to sound 

C +23.8 +15.7 

D +62.3 + 6.2 

E +30.1 - 2.3 

F +16.1 + 3.9 

Gen. Av +31.0 + 4.5 

II. Transfer of Training 

Gain by reacting to sound with no distraction. Subjects received no training to 

reacting to sound 

A +27.4(7 +12.4<r 

B -9.7 +2.2 

Gain by reacting to light with no distraction. Subjects received no training in reacting 

to light 

C +67.9 +15.7 

D +82.7 + 6.2 

E +21.9 - 2.3 

F + 4.8 +3.9 

Gen. Av +32.5 + 6.4 

III. Control Group 
Difference in prelim, test and final test for reactions to light. 

W +14.10- +19.2<r 

Z -5.1 +5.7 

Y -27.7 + 2.9 

V +17.8 +10.7 

X -18.1 + 9.2 

Gen. Av - 3.8 +9.5 



TRANSFER OF TRAINING 59 

Difference in prelim, test and final test for reactions to sound. 

W - 6.2<r -10.8<r 

Z +10.7 + 3.2 

Y + 2.0 +4.2 

V +10.2 + 5.4 

X + 3.0 +6.2 

Gen. Av + 3.9 +1.6 

The ability gained by reacting to a stimulus for a long time seems 
to be transferred bodily when reactions are made to another stimulus. 
Table XLV. indicates that a gain of 31.0 a was made by training 
with a specific stimulus, and a gain of 32.6 a- when reactions were 
made with another stimulus without previous training with it.^ 

IV. Training in Reaction with Distraction Shortens the 
Reaction to a Different Stimulus with the Same 

Distraction 

It was not possible to collect data from all the subjects on this 
problem lest it invalidate other data of more importance to this 
study. The data below are for A (trained with a light stimulus) 
and C (trained with a sound stimulus). 

TABLE XLVI 

A made gains as follows: 

Stimulus Distraction Gain 

Sound Light + 5.8<j- 

Sound Sound +77.3 

Sound Touch + 3.1 

Touch Touch + 6.0 

C made gains as follows: 

Light Sound +3S.7<t 

Light Light +32.0 

Light Touch — 6.3 

Av. Gain +32.2 

V. The Above Questions Examined Specifically in the Case 

OF Reaction to Touch. 

This comparison will show clearly the effect of practise in one 
performance on an unpractised performance. A and B were trained 
to react to light, and to light with touch (as well as light and sound) 
distraction; C, D, E, and F to sound, and to sound with touch (as 

2 While the data are treated as if no other training occurred it must be 
remembered that the subjects also made reactions to the same stimulus with 
distractions. Some of the practise gain is due to this training also. 



60 EFFECT OF DISTRACTION ON REACTION-TIME 

well as light and sound) distraction. Neither group received train- 
ing in reacting to touch, or to touch with touch distraction. Thus 
we are able to see what effect reacting to light had on the ability 
to react to touch; of reacting to sound on the ability to react to 
touch; and finally what result occurs when no training is given 
(control group). Table XL VII. gives this comparison. It seems 

TABLE XLVII 

Stimulus, Touch Distraction, Touch 

Subjects Gain in Time Gain in Var. Gain in Time Gain in Var. 

Trained by Reacting to a Light Stimulus alone, and to a Light Stimulus with Light, 

or Sound, or Touch as a Distraction 

A - 8.3<r - 3.9(7 +33.60- - 7.1<r 

B + 5.1 +11.2 +25.7 - 8.5 

Trained by Reacting to a Sound Stimulus alone, and to a Sound Stimulus with 
Sound, or Light, or Touch as a Distraction 

C +70.8 +27.2 +81.4 +26.7 

D +69.6 +16.2 +17.9 -6.7 

E +37.1 + 2.6 +30.7 - 5.2 

F +11.2 +4.6 +32.8 -10.6 

Gen. Av +30.9 + 9.6 +37.0 - 1.9 

The following group had no practise 

W..... - 6.3o - 3.9o- + 9.8(r + 6.2o- 

Z +30.4 +13.0 +17.7 -22.5 

Y + 8.6 +3.3 +29.7 +22.0 

V +19.2 +12.7 - 7.9 + 0.3 

X +41.2 + 5.2 +22.2 + 8.3 

Gen. Av +18.6 + 6.1 +14.3 + 6.9 

that familiarity with the touch distraction in other relations is 
carried over to this combination, as greater gain is shown with dis- 
traction present than in the simple reaction — which is not true of 
the control group. The practice group has certainly profited by 
its training with other stimuli. Even such gain as is shown by the 
control group may be due to the fact that the reactions made to touch 
and to touch with touch distraction were preceded by all the other 
reactions made in the control tests. 

VI. Training in Reacting without Distraction does not 

Appreciably Aid in Reacting to the same Stimulus with 

Distraction. (See the Records of E and F) 

During his training in reacting to a sound without distraction, 
E made a gain of 2.5 a, but his subsequent reactions to sound with 
sound distraction, and to sound with fight distraction were increased 



TRANSFER OF TRAINING 61 

0.5 (T, and 7.0 a- respectively. However, his time of reacting to 
sound with touch distraction was decreased 4.4 a. 

The reaction-time of F to a sound stimulus without distraction 
was reduced 18.8 a by special training. This training also reduced 
his reactions to sound with sound distraction 9.2 a-. 

The result here, then, is rather negative. Training in reacting 
without distraction does not aid much in reacting with distraction; 
and this agrees also with the introspective reports of the subjects. 
^Other experimenters have noticed that practise received in making 
simple reactions did not affect the time necessary to react when 
discrimination was necessary.^ 

VII. Training in Reacting with a Certain Distraction 
Shortens the Time of Reaction with a Different 
Distraction 

The data for Tables XLVIII. to LIII. were obtained from the 
preliminary and final tests of the practise control groups. See 
Tables XXXII. to XLII. 

A and B reacted throughout the experiment to the light stimulus, 
and their main practise was with light distraction. C, D, E, and F 
were trained in reacting to the sound stimulus, and their main 
practise was with sound distraction. The training of C and D 
was more extensive than that of E and F. F, W, X, Y and Z re- 
ceived no special training, but served as a control group. The 
tables indicate the gain or loss in both the practised performance 
and the unpractised performance with the practise group and the 
corresponding figures from the control group. A positive sign 
indicates a gain in ability, ^. e., the reaction time was shorter at the 
end of the experiment than at the beginning. A negative sign 
indicates the opposite condition. The difference in the variability 
of the two periods is indicated under ''Diff. in Var." This differ- 
ence is the difference between the mean variation in the pre- 
liminary test and the mean variation in the final test. A negative 
sign indicates greater variability in the final test than in the pre- 
liminary test. A negative sign in variability is not necessarily 
preceded by the same sign as the difference in the reaction time. 
The opposite seems more apt to be true. The subject takes chances. 
The reaction time is reduced by taking these chances, but the vari- 
ability is usually increased. 

It is obvious from Tables XLVIII. to LIII. that the greatest 
gain was made in the performance in which the most practise oc- 
curred. However, the gain of 75.1 sigma made by A when the 

' Gilbert and Fracker, op. cit. 
5 



62 EFFECT OF DISTRACTION ON REACTION-TIME 

sound stimulus was present may not be a true representation of A's 
actual gain. The initial reaction-time which permitted this great 
gain was 225.8 sigma. As the P.E. was 10.1 sigma it seems, without 
doubt, to be an eccentric record. 

Table LIV. was formulated from Tables XLVIII. to LIII. 
The special training was reacting to light, and to light with light, 
or sound, or touch distraction (A and B); and to sound, and to 
sound with sound, or hght, or touch distraction (C, D, E, F). The 
second line represents the gains made by A and B in reacting to 
sound, and to sound with sound, or light, or touch distraction; 
and the gains made by C, D, E and F in reacting to light, and to 
light with light, or sound, or touch distraction. The last line shows 
the gain made by V, W, X, Y, Z in reacting to light with light, or 
sound, or touch distraction, and to sound with sound, or light, or 
touch distraction. 

TABLE LIV 

Without Dist. With Dist. 
Gain made by special training +29.9cr +34. la- 

Gain made in reacting to another stimulus as the 

result of this special training +26.6<r +17.9<7 

Gain of the unpractised group + O.OSo- O.Oo- 

The summary was not made from the separate records of the 
previous tables, but from the averages of the data in these tables. 
If individual gains are used, the result is essentially the same, as 
follows : 

TABLE LV 

Without Dist. With Dist. 

Gain made by special training +30. Go- +33.3(r 

Gain made in reacting to another stimulus as the 

result of this special training +32. 5o- +20. To- 

Gain of the unpractised group + 0.7<7 + 0. So- 

Table LVI. is another summary of Tables XLVIII. to LIII. 
The averages here represent the general average of the individual 
records. 

TABLE LVI 

Av. Gain Av. Gain 

In Time In Var. 

Most trained performance +57.4a- + 8.3(7 

Same performance with the untrained — 2.1 + 3.0 

Less trained performance +22.0 + 9.1 

Same performance with the untrained + 1.1 +3.3 

Performance with no previous training in it +20.6 + 7.4 

Same performance with the untrained 0.0 + 3.2 



TRANSFER OF TRAINING 63 

The most trained performance was in reacting to light with Hght 
as a distraction, with A and B, and in reacting to sound with sound 
as a distraction with C, D, E, and F. 

A and B received less training in reacting to hght with sound 
or touch as a distraction. C, D, E, and F received the less training 
in reacting to sound with light or touch as a distraction. A and 
B received no training in reacting to sound with sound, hght, or 
touch as a distraction. C, D, E, and F received no training in 
reaction to light with light, sound or touch as a distraction. All 
these subjects, however, had received more or less training with all 
the distractions, as these were the same throughout the experiment, 
no matter with which stimulus they were used. 

From the table it may be seen that the ability gained by reacting 
to a particular stimulus with a particular distraction is a great aid 
to the subjects in reacting to a new stimulus with the same distraction, 
and in reacting to the same stimulus but with a different distraction. 

A priori, one would think that more transfer would be made 
in the last case, as the subject has become accustomed to the stimulus 
and has to accustom himself only to the distractions, whereas in 
the former case, he must accustom himself to the new stimulus while 
the distractions add their disturbance to the situation. Although 
the distractions were previously encountered when reacting in the 
training series the attention was always on the stimulus, and not 
on the distraction. Indeed, transfer was actually more prominent 
in accordance with these expectations, although the difference is 
slight, when compared with the difference between either one and 
the gain in the directly trained performance. 

From the previous tables it is quite obvious that the special 
training has a decided influence on other performances than the 
performance in which the training occurred. Gain in the perform- 
ance in which little training occurred was very noticeable. But 
even when no training was given in a performance the gain trans- 
ferred from the special training was more than 35 per cent, of the 
gain in that training. 

The transfer found here seems to be of two kinds. Ability 
gained in reacting to one stimulus aided in reacting to another 
stimulus. This was gain in the abiUty to do an act. But ability 
to ignore certain distractions was also transferred. This, however, 
was not gain in ability to do something but rather gain in ability 
not to do something, i. e., not to be influenced by the distraction. 

Tables LVII. to LIX. were obtained by taking the preliminary 
test, the first reactions and the last reactions in each practise series, 
and the final control test. While this comparison may not explain 



64 



EFFECT OF DISTRACTION ON REACTION-TIME 














{ 


^Vi 




(HP *• 

I 










1 
1 


f\ 


< 












^ 


T\ 


\ 


I 










1 
1 

1 


\ 


\ 












1 


i^ 


M 


O I 






^^ 


-^ 


f 




') 


or- 






c 


^ 
^ 


r 




1 







TRANSFER OF TRAINING 65 

why change occurs, it does indicate where change occurs. To il- 
lustrate: in the table for A and B the first reactions shown were made 
in the preliminary test. After training in reacting to light with 
Hght distraction the second series was obtained. The 209.8 a is 
A's reaction-time to light at the end of the practice period. The 
195.0 a- in the second column is his reaction-time to light with 
light distraction, while 218.0 a is the first reaction to the new series, 
the stimulus still being light but the distraction sound. The 
itahcized figures give the probable errors of the average immediately 
above. The results can perhaps be more readily appreciated from 
their graphic representations in Figs. 21 to 26. 

If the training effect of the work of the subjects was narrowly 
specific, the curve for each distraction should remain high till its 
own specific training had been given, then drop suddenly, then 
go up again to some degree after training with another distraction. 
If, on the contrary, the training effect was general (within the 
limits of the variations of the task here employed), all the curves 
should follow about the same course. Evidently the latter con- 
dition is approximately the fact. There is, in fact, no clear evidence 
of any extra benefit to a particular task from the special training 
in it. The gain occurs chiefly as the result of the first practice 
series with any distraction. It looks as it even the brief practise 
afforded by the preliminary tests was sufficient to give considerable 
adjustment to the distraction, for the distraction that came first 
in the preliminary series usually shows the most difference from the 
simple reaction. (Cf. Tables XXXII. to XXXVII.) 

VIII. Practise with a Given Distraction Shortens the 
Period of Adaptation to a New Distraction 

Another element in improvement due to previous training is the 
rapidity of the improvement, the rapidity with which a subject 
adapts himself to the new conditions. This has never been properly 
credited in the scheme of transfer. Under new conditions the 
subject shows more ability in the beginning than he showed in 

Figs. 21-26. 

The narrow vertical strips represent the successive cross-sections of the sub- 
jects' abiUties, as given in Tables LVII to LIX, and the broader strips represent 
the practise periods. The small circles without letters represent the simple 
reaction ability at each cross-section period; those circles with L inside give the 
reaction ability with light distraction, those with S with sound distraction, and 
those with T with touch distraction. The larger circles at the top of the broad 
strips symbolize the kind of training that occurred in each practice series. The 
letters in the upper circles indicate the distraction used, while the letter m the 
lower circle indicates the stimulus used. 



66 EFFECT OF DISTRACTION ON REACTION-TIME 

previous control test. In the course of the new work he tends to 
adjust himself more easily or to recover very quickly. 

We may notice some concrete examples of these points. 

Subject B in the beginning made a reaction of 212.8 a to light, 
and 260.3 a, to light with light distraction. The latter is soon 
reduced to 203.9 a and the simple reaction time to 191.3 <x. These 
represent about the physiological limit of the subject, who had had 
considerable training previously. Evidently, any further im- 
provement will be represented by small differences. Now when the 
distraction was changed to sound the pure reaction time was 195.0 cr, 
and the time with distraction was 196.5 o- with a variation of 10.5 o-. 
The initial performance in the preliminary control test to light with 
sound distraction had been 208.9 cr. 

In the preliminary test when touch distraction was present the 
time was 225.9 a, M.V. 8.1 a. This time was reduced to 222.6 a 
after training with light and sound distractions, and further reduced 
by special training to 219.9 a, M.V. 14.7 o-. 

Reference to the table will show the effect of the training upon 
the other activities of subject B. With the exception of sound there 
is a gain in reaction ability. The graphic representations show this 
quick drop in the curve due to quick adaptation to the new con- 
ditions. 

Subject A was untrained, and his preliminary records were very 
high, especially those with light, and light with light distraction. 
Considerable gain must be expected here. In the preliminary test 
the time of reacting to light with sound distraction was 241.9 a; 
while after practise with light distraction the new series with sound 
distraction began with 222.2 a. The shortest reaction-time in this 
series was 207.1 <x. If we use this as a basis of comparison, then 
the previous training brought an improvement in the unpractised 
performance of 70 per cent.'* With the touch distraction a similar 
gain of 45 per cent, was noticed. We may also observe that the 
limit of improvement is here reached after four hundred reactions, 
while 1,000 were required to reach the limit in the first practise 
series. Thus, the period of adjustment is reduced more than one 
half by the previous training in reacting with the other distractions. 

Table LX. gives a summary of the gain due to specific and to 
non-specific training. The figures under "Gain by Practise" give 
the gain within a series due to the specific practise of that series; 
they show the difference between the first reaction in the series and 

^ Since he reduced his time to but 207. lo- it is safe to say that in the beginning 
his range for improvement then was from 241.9o- down to 207. lo-, or a range of 
34.8(T, but 19.7o-, or approximately 70 per cent, of this reduction occurs before 
the time of practise in the performance. 



TRANSFER OF TRAINING 



67 



the quickest reaction made in that series. The "Entire Gain" is the 
difference between the quickest reaction in the series and the reac- 
tion made in the preHminary test. Subtracting the "Gain by- 
Practise" from the "Entire Gain," we have the gain not due to 
specific practise, but appearing at the outset of such practise as the 
result of previous practise with other distractions. This transferred 
gain, expressed as a per cent, of the "Entire Gain," appears in the 
last column. 

TABLE LX 



Subject. Performance 



Gain by Prac. Entire Gain. 



Stim. Dist. 
A Light Light U8.6<t US.Qcr 

" Sound 10.9 34.S. 

" Touch 15.9 29.2. 

B Light Light 63.6 63.4 

" Sound 4.0(?)5 12.4. 

" Touch 14.6 17.9. 

C Sound Sound 86.2 86.2 

" Light 22.4 60.8. 

" Touch 5.8(?) 21.8. 

D Sound Sound 35.7 35.7 



% of Gain 

before Prac. 

in the Perform. 



.70 

.45 



.69 
.19 



.64 

.74 



E Sound Sound 32.6... 

" Light 13.8... 

" Touch 2.5... 

F Sound Sound 39.4... 

" Light 10.1... 

" Touch 7.0(?) 



.32.1 
.37.4. 
.41.1. 
.48.6 
.65.5. 
58.3. 



.64 
.92 

.85 



TABLE LXI 



Subj. 
A.. 



Dist. 
. Light . 
Sound . 
Touch. 



Sittings 



Subj. 
B... 



Gen. Av. 66.9% 

Dist. Sittings 

.Light 2 



C Sound. 

Light . 
Touch 

E Sound . 

Light . 
Touch. 



■ Sound . 
Touch. 

D Sound. 



F Sound 3 

Light 

Touch 



It is safe to conclude that reacting to a stimulus with a distrac- 
tion gives aid in reacting to the same stimulus when a different 
distraction is used. 

^ The differences followed by a question mark are probably not characteristic, 
as the subjects showed much greater gain at other periods. The control reaction 
from which the difference was obtained was probably too high to represent the 
subject's abiUty. 



68 EFFECT OF DISTRACTION ON REACTION-TIME 

Table LXI. indicates the approximate number of sittings 
necessary before adaptation to each new distraction was so well 
established that no further rapid improvement occurred. 

The two tables indicate that the ability gained by special 
training influenced the following reactions under changed conditions 
of distraction. This was anticipated as the same motor path was 
functioning in all the reactions. The resistance of this path had been 
lowered by the first period of training. The introduction of each 
new distraction was accompanied by some resistance, as any dis- 
traction tends to produce some motor response, which may have 
been originally protective. Thus, a sound causes one to "start" 
or turn toward the source of the sound. Whether the energy will 
be directed into this original path or into the path established by 
practise will depend on how much training has been given. The 
subjects made this adjustment quickly. 

This is closely analogous to the state of attention. As the 
resistance in the pathway decreased the attention became more 
effective, the objective influences more automatically controlled. 
To disturb this pathway or increase the resistance, or divert the 
attention, some change must occur in the objective influences, e. g., 
the distraction might be made more intense. 

This is a physiological condition and is not to be confused with 
the mystical influence so often introduced in formal discipline. 

IX. Change in the Variability of the Reaction Time Due 

TO Practise 

The figures in Table LXII. show the average of the M.V.'s 
under the influence of the different distractions used. Practise 
with the several distractions occurred in the order shown for each 
subject in the table. 

TABLE LXII 

Distractions 
Subject Stim. Light Sound Touch 

A Light 12.7(r 7 Act 8.2<r 

B.24 " 6.8 8.5 8.1 

Gen. Av 9.8 7.9 8.1 

Sound Light Touch 

C Sound lO.Oa 5.7<r 5.4ff 

D " 9.7 

E " 8.2 5.9 4.1 

F " 6.4 4.4 3.5 

Gen. Av 8.5 5.3 4.3 

2* As B was the most practised subject at the beginning of the experiment 
more uniformity would be expected in his reactions, which seems to be the case. 



TRANSFER OF TRAINING 



69 



The effect of practise on the variability does not seem uniform. 
There is a uniform decrease with subjects C, E, and F, which is not 
so noticeable with A and B. The general averages indicate, how- 
ever, that practise does decrease the variability, and that this effect 
is carried over from practise with one distraction to practise with 
another. 

The effect of practise on the variability may also be noticed by 
reference to Table LXIII. In this case we have the relative varia- 
bility. This relative variability represents the average of a series 
of Pearson Coefficients, i. e., the general average of the variabilities 
found by dividing the gross variability of a group by its correspond- 
ing reaction time (i. e., the S Pearson Coefficients/w). 



TABLE LXIII 





Rel. Var. with no Dist.^ 






Suhj. 


Stim. 




Aver. 


A.. 


Light 

(I 


..045 
..037 






<( 


.032 


.038 


B.. 


Light 


.030 
.029 






(( 


.048 


.036 


C. 


Sound 


.043 
.033 






ti 


.035 


.037 


D.. 


Sound 


.046 




E.. 


Sound 


.047 






<< 


.045 






(( 


.034 






(( 


.031 


.040 


F.. 


Sound 


.039 






(( 


.034 






<( 


.047 






n 


.035 





With Dist. 



.039 



Gen. Av. 



.038 



Dist. 



Light 057 

Sound 034 

Touch 037 

Light 032 

Sound 043 

Touch 037 

Sound 071 

Light 042 

Touch 047 

Sound 065 

Sound 057 

Light .052 
Touch. 036 



Sound 052 

Light 039 

Touch 030 

.04S 



Aver. 



.043 



.037 



.053 



.049 



.040 



« Thorndike has suggested that the gross variability divided by the square 
root of the average would be in accord more with both theory and facts. But to 
treat our series in this manner would not change the data enough to influence our 
conclusion. For example, if the average of the sum of Pearson Coefficients is 
used the figures of variability are .033 and .042 for sound, and sound distraction, 
respectively, for C. If the Thorndike Coefficient is used the figures are .372 and 
.392 for the same series. Thorndike, "Mental and Social Measurements," p. 
133, 1913. 



70 EFFECT OF DISTRACTION ON REACTION-TIME 

There was a more uniform decrease when distraction was present 
than when it was not present. In the case of E and F there is a 
definite and uniform decrease with distraction present, but this 
uniformity is not so noticeable in their reactions without distraction. 

This table also shows whether a subject is more variable in 
reacting with or without distraction. The first column in the table 
represents the variability of the series when no distraction was used. 
The second series indicates the variability when distraction was 
used. 

Although the difference is small, in most cases the subjects are 
more variable in their reacting when the distraction was present. 
There are four exceptions. If only the general average of the vari- 
ability for each subject both with and without distraction is noted, 
then every subject is more variable when the distraction was 
present than when it was not used. There is, accordingly, a 
tendency, to be more variable when distraction is present, but this 
tendency is decreased by practise. 

X. Summary of Conclusions 

1. The ability gained by prolonged practise in simple reaction 
to one stimulus seems to be transferred bodily when reactions are 
made to another stimulus (p. 58). 

2. A very definite gain was made when reactions were made to 
a stimulus different from the one used in practise but with the same 
distractions (p. 59). 

3. Training in reacting to a stimulus without distraction has very 
little effect on reacting to the same stimulus with a distraction, 
except, possibly to cause a slight reduction in variability. 

4. Practise in reacting to a particular stimulus with a particular 
distraction aids in reacting to a new stimulus with the same dis- 
traction, or to the same stimulus but with different distractions. 

5. Practise has a tendency to decrease the variability of reaction 
time. Practise reduces the period of adaptation to other reaction 
performances. 

6. Training of Attention. — To attend well means ability to 
ignore non-essentials for the sake of the essentials. The essentials 
have been brought to the front by the development of certain 
valuable habits. The development of these habits has been in 
opposition to the influences of distraction. The subject has ac- 
quired certain adjustments to the constant conditions of his work. 
Useless reactions have been repressed early in the practice period. 
With this ability to ignore the non-essential stimuli comes a certain 
feeling of self-confidence and self-reliance which stimulates the 



TRANSFER OF TRAINING 71 

subject to active interest in the work. It is this attitude or adjust- 
ment which makes transfer possible. We could expect little or no 
transfer effect to result from practise if an attitude or "set" or 
neural adjustment which had been previously acquired could not 
be used in the new situation. 

This experiment well illustrates the above conditions. In 
developing the power of ignoring the distracting influences, atten- 
tion was, in effect, developed. The ability to ignore the unessential 
and to subordinate the minor to the major elements of the situation 
is synonymous with good attention. The more chances afforded 
to develop these good habits of attention, the more possibility there 
will be for transfer to occur. 



TABLES OF RESULTS 

TABLE I 

Subject A Stimulus Light Distraction Light 

Reaction Without Distraction Reaction With Distraction 

Date Time M.V. P.E. Time M.V. P.E. R. Av. of R. 

Nov. 17 261.4 20.5 5.1 343.3 13.2 3.4 1,31 

23 213.1 16.1 9.5 323.8 42.7 10.2 1.52 

25 222.6 28.1 21.6 303.4 23.3 6.5 1.36 

26 268.0 22.2 13.1 274.2 27.1 7.0 1.02 

29 278.8 29.1 17.1 269.3 18.5 4.8 _^96 

30 238.8 2.4 1.4 270.7 16.4 4.2 1.13 1.23 

Dec. 1 295.6 28.8 13.8 263.9 17.1 4.5 .89 

6 232.7 1.0 0.6 212.3 8.5 2.1 .91 

8 212.3 9.8 5.8 209.0 21.6 5.4 .98 

9 208.8 20.7 12.2 221.5 14.4 3.5 L06 

12 184.9 6.3 3.7 209.7 9.5 2.5 1.13 .99 

13 218.5 7.9 3.0 220.6 11.6 2.9 1.00 

19 224.0 9.0 3.3 

26 194.5 3.4 1.6 212.6 7.5 2.0 1.09 

229.1 18.8 4.5 1.17 

29 209.8 6.5 3.1 210.3 8.0 2.1 1.00 

29 197.9 3.3 1.6 202.5 14.7 3.7 1.02 1.08 

30 202.3 5.1 2.4 206.6 6.1 1.6 1.02 

31 208.0 39.8 19.1 206.5 7.7 2.0 .97 

31 213.6 5.6 2.9 218.1 10.1 2.6 1.02 

31 224.2 6.4 3.1 222.1 6.5 1.7 _^99 

31 206.5 15.8 9.2 219.0 6.7 1.7 1.06 1.00 

Jan. 1 201.6 8.3 4.0 215.3 9.2 2.4 1.06 

1 202.2 6.4 3.1 210.7 6.3 1.6 1.04 

2 226.5 10.7 3.9 243.3 12.6 3.3 1.07 

3 209.5 7.8 2.9 212.4 10.4 2.7 IM 

5 222.4 6.5 2.4 221.7 6.9 1.8 .99 1.05 

6 216.5 4.2 1.5 206.8 17.9 4.5 .95 

10 213.6 7.5 2.8 217.7 6.9 1.7 1.01 

13 215.8 13.1 6.3 201.0 15.0 3.9 .93 

214.4 7.6 2.1 _^99 

16 214.4 7.9 3.4 204.4 12.0 3.0 .95 .97 

22 208.7 1.1 3.5 194.7 6.3 1.6 .93 

198.7 12.3 3.0 .95 

Feb. 4 205.5 7.8 2.5 193.1 9.1 2.4 .93 

202.7 11.0 2.7 _^98 

7 232.8* 5.6 2.1 211.5 5.2 1.3 .90 .95 

205.6 13.0 3.4 .88 

10 218.4 9.0 3.3 203.9 8.9 2.2 .93 

13 209.8 4.0 1.5 195.0 11.4 2.8 _^93 

.91 

Av 222.7 11.1 225.2 12.7 

Relative variability 045 Relative variability 057 

* The subject stated, after these reactions were taken, that he had just pre- 
viously suffered from toothache, but had allayed the pain with drugs. Evidently 
the effect of the drugs was still present when the reactions were made. It seemed 

that this influence was partially overcome by forced attention when distraction 
was introduced. 

72 



TABLES OF RESULTS 



73 



Subject B 
Reaction Without Distraction 
Date Time M.V. 

Dec. 10 212.8 3.9 1, 

13 200.1 18.2 8, 

Feb. 17 193.2 4.0 1, 

18 191.3 2.5 0. 

20 199.6 4.3 2, 

21 199.4 7.7 2, 

22 188.7 5.0 1. 

25 201.3 3.6 1. 

28 198.7 5.9 2. 

Mar. 7 195.0 4.7 1. 

Av 198.0 6.0 

Relative variability 



TABLE II 

Stimulus, Light Distraction, Light 

Reaction With Distraction 
P.E. Time M.V. P.E. R. Av. of R. 



.9 


260.3 


13.9 


3.5 


1.22 




.7 


220.1 


10.2 


2.7 


1.09 




.0 


203.9 


5.7 


1.5 


1.05 






209.2 


4.8 


1.2 


1.08 




.9 


206.3 


6.3 


1.6 


1.07 






212.3 


5.6 


1.4 


1.10 


1.12 


.0 


207.6 


3.8 


09 


1.04 




.8* 


214.8 


5.3 


1.4 


1.07 






210.1 


12.3 


4.4 


1.05 






215.3 


4.6 


1.2 


1.07 






215.2 


6.7 


1.7 


1.07 


1.07 


.8 


196.9 


6.4 


1.6 


1.05 






205.4 


8.4 


2.2 


1.08 






208.9 


4.8 


1.2 


1.10 




,3 


196.7 


4.7 


1.2 


.97 






191.2 


6.8 


1.7 


.94 


1.05 


,2 


198.3 


7.5 


1.9 


.99 






214.8 


5.6 


1.4 


1.08 




.7 


199.4 
209.8 


6.0 
6.8 


1.5 


1.02 


1.01 


.030 


Relative variability. . 




.. .03^ 



TABLE III 

Subject A Stimulus, Light Distraction, Sound 

Reaction Without Distraction Reaction With Distraction 

Date. Time. M.V. P.E. Time. M.V. P.E. R. Av. of R, 

Feb. 16 211.9 10.3 3.8 218.0 6.8 1.7 1.02 

17 205.2 6.2 2.3 222.2 4.3 1.1 1.08 

20 251.5 6.8 2.5 207.7 6.4 1.7 1.53 

23 213.3 8.1 3.0 214.3 8.1 1.1 1.00 

208.4 7.7 2.1 .97 

24 206.4 4.2 1.5 210.5 8.3 2.2 1.01 1.02 

210.3 6.0 1.5 1.01 

Mar. 7 205.8 11.0 4.1 207.1 8.0 2.1 1.55 

14 217.2 8.7 3.2 233.2 8.0 2.1 1.07 

218.8 7.7 1.9 1.00 

1.02 

Av 209.3 7.6 214.9 7.4 

Relative variability 037 Relative variability 034 

* Series taken throughout the day. 



74 



EFFECT OF DISTRACTION ON REACTION-TIME 



TABLE IV 

Subject B Stimulus, Light Distraction, Sound 

Reaction Without Distraction Reaction With Distraction 

Date Time M.V. P.E. Time M.V. P.E. R. Av.ofR. 

Mar. 7 195.0 4.7 1.7 196.5 10.5 2.6 1.01 

10 204.8 4.9 2.0 200.5 7.8 2.0 .97 

211.9 4.2 1.1 1.03 

15 203.21 9.9 3.6 198.3 8.0 1.9 .97 

17 227.8 5.3 1.9 224.8 14.5 3.7 _^98 

18 210.0 8.0 0.4 199.2 7.4 2.5 .94 .99 

24 200.9 5.2 1.9 201.6 6.6 1.7 1.00 

210.4 8.6 2.2 1^04 

.99 

Av 206.9 6.3 205.4 8.5 

Relative variability 029 Relative variability. 043 



TABLE V 

Subject A Stimulus, Light Distraction, Touch 

Reaction Without Distraction Reaction With Distraction 

Date Time M.V. P.E. Time M.V. P.E. R. Av.ofR. 

Mar. 19 221.6 10.8 4.0 224.7 6.3 1.6 1.05 

20 197.4 7.6 2.8 207.7 7.1 1.8 1.10 

223.9 11.1 2.6 1.11 

219.4 7.8 2.0 1.11 

220.8 8.5 2.1 L04 

21 202.7 3.2 1.2 212.6 7.7 1.9 1.03 1.08 

208.8 10.6 2.6 1.02 

218.5 6.1 1.4 1.03 

25 213.3 5.7 1.9 221.8 8.9 3.3 1^08 

1.04 

Av 208.7 6.8 217.6 8.2 

Relative variability 032 Relative variability 037 

TABLE VI 

Subject B Stimulus, Light Distraction, Touch 

Reaction Without Distraction Reaction With Distraction 

Date Time M.V. P.E. Time M.V. P.E. R. Av. of R. 

Mar. 19 202.3 10.4 3.8 222.6 6.1 1.6 1.10 

30 210.2 4.3 1.6 211.6 5.3 1.4 1.00 

216.5 10.3 2.7 1.03 
212.4 10.1 2.6 1.01 

214.6 8.7 2.2 1^02 

31 207.3 15.3 5.6 220.2 10.6 2.7 im 1.03 

208.0 5.6 1.4 1^00 

Av 206.6 10.0 215.1 8.1 

Relative variability 048 Relative variability 037 

1 Becomes 198.0 if the first average (224.1, M.V. 20.9) of the first set is 
omitted. 



TABLES OF RESULTS 



75 



TABLE VII 

Subject C Stimulus, Sound Distraction, Sound 

Reaction Without Distraction Reaction With Distraction 

Date Time M.V. P.E. Time M.V. P.E. R. Av. of R. 

Nov. 14 139.0 7.6 1.9 206.0 19.7 4.7 1.48 

15 218.9 7.6 2.0 1.57 

18 202.3 22.2 5.1 1.45 

19 199.4 23.5 5.9 1.43 

20 149.2 9.4 2.2 LOT 

21 151.2 18.7 4.5 1.08 1.40 

158.2 22.3 5.5 1.13 

24 143.3 4.4 2.1 160.3 20.0 5.2 1.11 

25 150.0 9.1 5.3 142.5 9.7 2.4 .95 

26 110.0 5.7 3.3 133.1 8.7 2.2 L21 

29 119.6 5.7 3.3 143.7 15.5 4.0 1.20 1.09 

Dec. 1 116.1 9.6 5.6 144.6 7.4 1.9 1.24 

6 119.1 1.9 1.1 159.9 11.2 2.9 1.34 

8 109.3 5.5 3.2 137.8 13.3 3.4 1.26 

9 113.1 0.2 0.1 143.2 10.6 2.7 1^ 

12 133.8 4.4 2.6 148.4 19.2 4.8 1.10 1.26 

13 128.8 12.6 6.0 150.1 13.1 3.3 1.17 

Jan. 1 106.1 7.3 3.5 119.8 4.9 4.4 1.12 

136.3 7.0 1.8 1.28 

10 114.7 1.2 0.6 133.5 9.5 2.5 116 

19 123.2 4.4 1.6 137.4 7.4 1.9 1.11 1.17 

22 120.7 7.0 2.6 152.6 21.1 5.5 1.26 

23 130.4 4.6 2.2 133.2 7.4 1.9 1.02 

128.1 7.3 1.9 .98 

Feb. 9* 125.9 5.6 2.0 145.0 7.4 2.5 L15 

150.9 6.6 1.6 1.11 1.10 

144.5 10.2 2.6 1.14 

139.1 6.1 1.6 1.10 

10 130.1 6.4 2.3 149.1 7.0 1.8 1.14 

132.9 6.2 1.6 im 

12 117.6 3.8 1.4 129.3 5.6 1.4 1.09 1.10 

13 125.3 5.4 2.0 134.7 9.2 2.4 1.07 

137.4 6.2 2.5 1.08 
17 116.1 2.8 1.0 129.2 6.0 1.4 1.11 

18 122.6 2.9 1.4 136.0 6.6 1.4 L12 

19 122.9 2.8 1.0 137.6 5.1 1.3 1.12 1.09 

20 130.9 5.2 1.7 131.8 8.5 2.2 1^00 

1.06 

Av 123.7 5.3 140.2 10.0 

Relative variability 043 Relative variability 071 

* The first two records for Feb. 9 were made at 1 p.m.; the last two at 3 p.m. 



76 



EFFECT OF DISTRACTION ON REACTION-TIME 



TABLE VIII 

Subject C Stimulus, Sound Distraction, Light 

Reaction Without Distraction Reaction With Distraction 

Date Time M.V. P.E. Time M.V. P.E. R. Av. of R. 

Feb. 20 130.9 5.2 1.7 148.2 9.5 2.5 1.13 

24 121.6 4.8 1.8 144.3 7.9 2.1 1.18 

143.3 1.0 1.5 1.17 
25 114.3 1.0 0.5 125.8 6.6 1.7 1.10 

27 125.8 9.3 3.4 134.9 5.1 1.3 LOT 

Mar. 3 115.8 2.4 0.9 127.0 5.0 1.3 1.09 1.03 

126.4 4.4 1.2 1.09 
9 119.6 2.1 1.2 130.9 4.7 1.2 1.09 

130.0 7.5 1.9 L08 

1.09 

Av 121.3 4.1 134.5 5.7 

Relative variability 033 Relative variability 042 



Subject C 

Reaction Without Distraction 

Date Time M.V. 

Mar. 2 110.4 3.1 

16 121.6 1.9 

20 117.8 7.3 

24 116.8 2.5 

24 116.2 6.3 

28 115.2 3.9 



Av 116.2 4.2 

Relative variability 035 



TABLE IX 










Stimulus, Sound 


Distraction, 


Touch 


n 




Reaction With Distraction 


P.E. 


Time 


M.V. 


PJJ. 


R. 


Av. of R 


1.1 


121.8 


5.5 


1.5 


1.10 




0.7 


127.6 


6.4 


1.6 


1.04 






124.2 


4.5 


1.2 


1.02 




2.7 


132.4 


5.3 


1.3 


1.12 




2.3 


127.0 
121.8 


4.7 
5.9 


1.2 
1.5 


1.08 




0.9 


1.04 


1.09 


1.4 


125.0 


5.7 


2.1 


1.08 





1.06 
125.7 5.4 
Relative variability 047 



TABLES OF RESULTS 



77 



TABLE X 

Subject D Stimulus, Sound Distraction, Sound 

Reaction Without Distraction Reaction With Distraction 

Date Time M.V. P.E. Time M.V. P.E. R. Av. of R. 

Nov. 28 134.4 8.1 4.8 166.7 17.3 4.5 1.24 

Dec. 8 124.7 6.2 3.6 153.8 10.0 2.6 1.23 

11 125.1 6.2 2.6 154.5 12.9 3.3 1.23 

12 136.9 2.2 1.3 143.4 12.8 3.6 1.05 

Jan. 3 124.4 4.6 2.2 161.3 11.4 2.3 ^29 

6 123.6 8.4 3.1 142.8 11.0 2.9 1.15 1.21 

141.7 6.6 1.7 1.14 
23 133.2 6.3 2.3 135.8 6.1 1.6 1.02 

142.6 12.7 3.3 1.07 

131.0 7.7 2.0 ^98 

138.9 7.3 1.9 1.04 1.07 

Feb. 5 128.1 3.4 1.2 151.6 8.2 2.1 1.23 

136.8 8.0 2.1 1.06 
140.3 4.2 1.1 1.09 

149.3 9.1 2.3 1^16 

133.2 9.0 2.1 1.04 1.12 

12 117.3 2.8 1.0 149.8 11.0 4.1 2:27 

Av 127.5 5.4 147.1 9.7 

Relative variability 046 Relative variability 065 



78 



EFFECT OF DISTRACTION ON REACTION-TIME 



TABLE XI 





Part A 








PartB 






Stimulus 


!, Sound 








Distraction, None 






Subject E 








Subject F 






Date 


Time 


M.V. 


P.E. 


Date 




Time 


M.V. 


P.E. 


Dec. 12. . . 


...141.5 


7.4 


2.5 


Jan. 22. 




. . 140.0 


3.1 


1.1 


Feb. 5... 


. . . 123.6 


14.6 


5.4 


Feb. 12. 




. . 137.0 


2.9 


0.7 


10... 


. . . 136.6 


9.8 


2.5 






137.7 


4.6 


1.2 




143.1 


5.3 


1.3 






148.0 


5.7 


1.3 


12... 


...135.7 


8.9 


2.3 






144.8 


7.1 


1.8 




127.4 


4.8 


1.0 


13. 




..135.6 


7.4 


1.7 




125.1 


3.0 


0.7 






132.5 


4.0 


1.0 


14... 


...131.9 


6.4 


1.6 






139.9 


6.6 


1.7 




131.1 


5.8 


1.5 






137.4 


6.8 


1.6 




133.2 


4.7 


1.2 


14. 




. . 125.5 


4.6 


1.2 


16... 


...137.0 


8.7 


2.2 






119.5 


5.4 


1.4 




126.3 


2.4 


0.6 






110.4 


5.2 


1.3 


17... 


...130.2 


6.8 


1.7 


16. 




. . 127.8 


4.7 


1.1 




126.5 


10.9 


2.6 






124.8 


4.3 


1.3 


24. . . 


. . . 139.0 


9.0 


3.3 


21, 




. . 148.6 
127.1 
118.4 


10.7 
6.3 
4.5 


2.8 
1.6 
1.2 










25 




. . Omitted 












27 




. . Omitted 












Mar. 9 




..121.2 


1.6 


0.6 










12 




. . 122.9 
120.3 


5.7 
3.4 


1.5 
0.9 


Av 


...132.5 


7.2 




Av 




, . . 130.0 


5.2 




Relative variability. . 




. .047 


Relative variability . . . 




.. .039 








TABLE XII 










Subject E 




Stimulus, Sound 




Distraction, Sound 


Reaction Without Distraction 


Reaction With Distraction 


Date 


Time 


M.V. 


P.E. 


Time 


M.V. 


, P.E. 


R. 


Av. of R. 


Feb. 24. . . 


...139.0 


9.0 


3.3 


153.7 : 


10.3 


2.7 


1.10 




28... 




Omitted 


Omitted 






Mar. 2... 


, . . . 128.3 


11 
5.2 


1.9 


150.8 
156.8 


5.5 
7.5 


1.5 
2.0 


1.17 
1.22 




6.. 


....126.9 


4.3 


1.6 


151.7 : 


23.5 


3.0 


1.19 






....124.0 


7.9 


2.9 


161.1 
137.6 


6.8 
9.5 


1.7 
2.5 


1.26 




7.., 


1.10 


1.19 


9.. 


. . . . 128.2 


5.9 


2.0 


130.1 
123.1 


4.9 
3.9 


1.3 
1.0 


1.01 
.96 










10.. 


....119.6 


4.1 


1.5 


133.8 
130.6 


4.1 
3.1 


1.3 

0.8 


1.11 
1.09 




12.. 


....120.6 


7.0 


2.4 


126.0 


6.1 


1.6 


1.00 


1.05 


15.. 


....107.5 


3.1 


1.1 


121.1 


4.7 


1.2 


1.12 


1.06 


Av 


. . . . 124.2 


5.8 




138.4 


8.2 








Relative variability. . 




. .045 


Relative variability. . . 




.. .057 



TABLES OF RESULTS 



79 



TABLE XIII 

Subject F Stimulus, Sound Distraction, Sound 

Reaction Without Distraction Reaction With Distraction 

Date Time M.V. P.E. Time M.V. P.E. R. Av. of R. 

Mar. 9 121.2 1.6 0.6 147.4 14.5 3.6 1.21 

12 113.1 4.2 1.5 125.6 6.8 1.7 1.11 

15 111.0 2.7 1.0 118.8 2.8 0.7 1.07 

17 115.5 2.7 1.0 118.5 5.5 1.4 1.02 

124.9 6.9 1.7 L08 

17 115.1 3.7 1.3 120.3 6.5 1.6 1.04 1.10 

18 117.5 6.6 2.4 120.4 3.0 0.8 1.02 

119.2 8.2 2.1 1.01 

19 113.5 5.5 2.0 108.0 3.2 0.8 .95 

117.1 6.5 1.6 L03 

1.01 

Av 115.3 3.9 122.0 6.4 

Relative variability 034 Relative variability 052 



TABLE XIV 

Subject E Stimulus, Sound Distraction, Light 
Reaction Without Distraction Reaction With Distraction 

Date Time M.V. P.E. Time M.V. P.E. R. Av. of R. 

Mar. 17 118.6 3.5 1.3 119.5 7.5 1.9 1.00 

115.5 9.6 3.5 115.4 5.7 1.4 .98 

120.5 4.3 1.1 1.04 

19 114.0 3.4 1.2 114.3 7.5 1.9 1.00 

115.8 6.5 1.6 JJOl 

20 110.2 0.6 0.2 116.8 3.1 0.8 1.06 1.01 

114.3 5.2 . 1.3 1.03 

110.8 3.4 0.8 1.00 
21 111.1 4.0 1.5 113.9 3.1 0.8 1.02 

108.5 2.6 0.7 ^97 

21 119.1 5.7 1.1 1.07 1.02 

110.9 4.5 1.2 .99 
107.1 5.0 1.2 .96 

22 111.4 3.3 1.1 105.7 18.5 6.3 ^95 

.99 

Av 113.4 4.1 113.7 5.9 

Relative variability 035 Relative variability 052 



80 



EFFECT OF DISTRACTION ON REACTION-TIME 



TABLE XV 

Subject F Stimulus, Sound Distraction, Light 

Reaction Without Distraction Reaction With Distraction 

Date Time M.V. P.E. Time M.V. P.E. R. Av. of R. 

Mar. 20 112.6 5.5 2.0 111.7 2.3 0.6 .99 

113.0 5.2 1.3 1.00 

24 121.4 5.9 2.0 116.1 3.7 1.0 .96 

117.4 6.6 1.6 .96 

24 107.5 3.8 1.4 109.9 5.5 1.4 L02 

109.5 4.1 1.0 1.02 .99 
25 104.3 6.0 2.2 101.6 3.8 0.9 .97 

.99 

Av 111.5 5.3 111.3 4.4 

Relative variability 047 Relative variability 039 



TABLE XVI 

Subject E Stimulus, Sound Distraction, Touch 

Reaction Without Distraction Reaction With Distraction 

Date Time M.V. P.E. Time M.V. P.E. R. Av. of R. 

Mar. 21 106.3 3.6 1.3 111.0 5.2 1.3 1.04 

111.3 5.5 1.3 1.04 

111.4 3.3 1.1 1.04 
Mar. 22 111.4 3.3 1.1 118.9 3.3 0.8 1.06 

113.8 5.6 1.4 im 

" 22 111.3 6.2 1.6 .99 1.04 

108.5 2.6 0.7 .97 
" 22 109.6 2.8 0.7 .98 

109.9 2.8 0.7 _^98 

.98 

Av 109.7 3.0 111.7 4.1 

Relative variability 031 Relative variability 036 



TABLE XVII 

Subject F Stimulus, Sound Distraction, Touch 

Reaction Without Distraction Reaction With Distraction 

Date Time M.V. P.E. Time M.V. P.E. R. Av. of R 

Mar. 25 Omitted Omitted 

26 112.2 2.4 0.9 108.1 3.2 0.8 .96 

115.1 3.1 1.1 115.5 2.6 0.7 1.00 

112.8 3.6 0.8 .98 

27 112.1 3.8 1.0 108.5 2.6 0.7 .96 

112.2 4.1 1.0 im 

114.7 3.0 0.8 1.02 .98 

Apr. 1 123.9 8.3 3.1 135.0 5.7 1.5 J^OS 

1.05 

Av 115.8 4.4 115.2 3.5 .030 

Relative variability 035 Relative variability 



TABLES OF RESULTS 81 

Dally Work of C. 
Simple ReaCtl'jP-t Ime React ion-t, Une with Dlatraotlon. 



U6.0 


13 ...7 


14-) 9 


137.4 


135.7 


:35.4 


238.6 


2ir>.9 


<;1.^.0 


165.1 


167.6 


194.8 


178.4 


21fi.6 


202.4 














i^6.4 


239,5 


221.5 


2111.6 


226.5 


219.3 


204.0 


212.6 


207.0 


217.4 














213,1 


180.'' 


191.3 


lei. 7 


226.1 


191.2 


224.9 


216.1 


194.5 


202.7 














1U4 . 7 


179.3 


172.0 


178.8 


176.2 


228,6 


177,6 


200.2 


146.8 


167.6 














170.4 


145.1 


159.2 


134.3 


137.7 


140,9 


141.5 


149.8 


167,9 


166.0 














17:i.2 


158.4 


100,4 


141.6 


163,0 


150.4 


112.4 


161.2 


140.0 


171.6 














202.4 


152.8 


103.9 


215.9 


169.0 


168.2 


139. B 


149.1 


148.2 


145.4 




Ui,l 


161.1 


135.9 






199.6 


167,3 


146.6 


170.3 


177.0 


146.0 


129.2 


144.7 


135.7 


194.6 




193.9 


isy.i 


141.0 






119.7 


151.2 


153.7 


144.0 


148.0 


138.7 


134.6 


134.2 


142,6 


150,6 




115.8 


104 . 3 








133.2 


126.3 


140.9 


142.9 


143.5 


116.7 


133.6 


118.6 


143,4 


132.1 




113.9 


li5.4 








1.27.1 


li;l^ 


135.7 


204.8 


143.7 


156,6 


136.0 


136.5 


147.2 


128.3 




125. 7 


1^.5 








133.0 


127,0 


151,0 


154.0 


149.0 


144.9 


159.5 


140 , 4 


141.1 


146.8 




Ul.O 


117.2 








152.5 


149.4 


170.3 


163.2 


151.4 


158.5 


131,6 


166," 


190.6 


165.0 




114.8 


103.8 








152.5 


150.1 


117.1 


133.3 


135.7 


134.2 


116.1 


124.0 


159.9 


166.5 




113. 


113..^ 








135.1 


149.8 


140.8 


151.2 


176.7 


136.2 


148.5 


120.8 


130,2 


143.3 




12S.4 


136.2 








140.?. 


135.7 


127.1 


138.2 


166.1 


134.0 


191.2 


133.4 


193.9 


136.6 




13£.l 


109.8 


14 4.5 






128.8 


161.9 


151.6 


165.1 


134.2 


116.2 


163.8 


162.7 


153.0 


162.3 




109.3 


95.1 


113.8 






119.9 


122.1 


110.1 


115.9 


127.3 


116.8 


114.3 


131.7 


119.9 
















139.4 


121.7 


129.4 


136.3 


147.3 


122.7 


145.9 


139.5 


138.9 


141.9 




114.1 


11;^. 6 


116.5 






113.3 


125.1 


121.5 


132.8 


146.4 


128.8 


133.7 


160.2 


132.1 


141.3 




124.. "t 


118. •» 


130.7 


125.6 


116.6 


111.5 


136,2 


133.7 


137.5 


158.5 


131.5 


146.1 


137.2 


142.9 


139.5 




111.9 


123.4 


112.0 


126.2 


128.1 


171.7 


143.5 


126.0 


130.6 


210,7 


108.5 


144.6 


161.9 


160,2 


165.5 




126.2 


137.4 


127.7 






125.2 


145.0 


136.5 


123.5 


122.1 


144.6 


140.8 


136.2 


127,4 


130.8 














127.7 


125.0 


137.5 


126.8 


101.8 


135.4 


122.5 


142.7 


128.5 


133.6 




Xl2..'i 


130.2 


125.2 


129.0 


132.6 


129.7 


139,0 


144.5 


156.3 


147,6 


151.6 






















143.4 


154,6 


163.8 


154.5 


151,6 


149.9 


158.0 


139.2 


143.2 


150.8 














139.6 


145,2 


116.8 


128.5 


151.4 


164.1 


148.8 


157.0 


141.8 


152.0 














131.0 


142.4 


139.4 


130.3 


137,0 


144.6 


154.2 


129.6 


145.7 


136.2 




lie. 4 


131.5 , 


, 125.8 


130.3 


144.4 


141.5 


140.5 


133.9 


150.5 


148.9 


149.8 


146.2 


164.3 


157.4 


157.3 














136.3 


127,5 


128.8 


141.7 


135.7 


136.5 


143.5 


125,5 


116.9 


136.1 




116.8 


123.0 


116.3 


110.4 


121.7 


130,9 


123.7 


123.2 


128.5 


128.3 


14fi.O 


123.4 


119.7 


139.6 


129.2 




111.6 


127.5 


126.8 


128.9 


131.5 


163.5 


135.3 


125.9 


131.6 


128.6 


129.6 


127.0 


119.6 


146.8 


139.5 














129.2 


123.5 


131.3 


151.5 


145.7 


142.1 


168.8 


150.2 


125,7 


126.8 




110.5 


116.0 


122.9 


116.2 


114.9 


131.5 


119.9 


130.9 


132.1 


144.6 


132.0 


135,3 


130.4 


130,8 


126.6 




124.1, 


'12^.7 


123.1 


122,7 


115.4 


119.1 


126.1 


155.4 


136.2 


140.3 


137.5 


140.3 


131.4 


134.3 


139.S 




124. ^ 


117.5 


::5.o 


122.9 


123.9 


135.4 


131.0 


124,8 


131.2 


140.6 


150.4 


140.2 


140.1 


137,7 


141.3 




138.1 


134.9 


131.9 


127.4 


126.8 


125.6 


125.3 


124.6 


125.0 


140.5 


116.7 


128.6 


145.3 


140,7 


143.6 




124.6 


123.8 


127.3 


125.1 


126.5 


155.3 


145. J 


141,5 


157.4 


168.5 


146.3 


147.0 


142.8 


148.6 


151.4 




138.1 


134. S 


131.9 


127.4 


126.8 


:71.1 


151.1 


145.7 


142.7 


136.2 


136.6 


143.2 


144.2 


142.9 


126.5 




125.9 


122. 8 


ii3.5 


ii5.6 


iio.O 


143.5 


133.3 


134.4 


154.1 


145.7 


132.2 


143.7 


146.6 


143.9 


153. A 














143.5 


127,8 


l;i5.2 


127.3 


124.2 


132,0 


112.5 


134.6 


141.9 






112.9 


114.5 


116.6 






134.2 


128,4 


127.9 


132.7 


120.7 


137.3 


115.6 


127.6 


117.5 


116.4 




121.2 


112.1 


133.6 


120.9 


141.5 


124.0 


139.7 


136.3 


142.0 


134.6 


132.1 


126.6 


145.3 


132.8 


131.7 




115.9 


113.0 


112.6 


119.8 


117.7 


125.7 


131.1 


131.7 


120.0 


133.0 


U7.5 


122.6 


136.4 


123.4 


124.1 














127.9 


125.3 


127.8 


116.2 


131.7 


129.9 


118.1 


127.4 


133.6 






118.1 


116.0 


123.2 


121.2 


119.5 


126.2 


132.8 


126.3 


137.9 


138.4 


126.6 


130.7 


135,7 


153.4 


122.6 














113.3 


116.1 


121.1 


133.6 


126.9 


131.5 


138.4 


132,7 


144.4 


137.3 




118.1 


115.6 


119.7 


121.8 


123.4 


131.7 


130.8 


141.9 


134.1 


132.6 


130.8 


126.2 


137,0 


135.4 


130.6 G«n. A7. 


116.2 


106.8 


112.3 


108.7 


107.9 


164.0 


155.4 


154.1 


144.9 


137.5 














120.5 


122.1 


122.4 


125.0 


118.1 


132.7 


123.0 


122.0 


116,0 


117.4 


131,0. 


119.4 


110,4 


125.0 
















134.2 


115.4 


143.9 


123.8 


126.8 


126,4 


130.9 


123,1 


133.5 


116,0 




106.0 


116.4 


127.9 


126.0 


112.8 


129.0 


119.5 


129.6 


131.4 


128.5 


119,6 


122.6 


123,7 


125.6 


112.6 




120.4 


116.4 


112.6 


119.6 


114.9 


133.9 


136.1 


127.7 


123.4 


121.3 


133.6 


139.7 


135.9 


137.9 


138.7 




124.0 


109.0 


117.7 


122.6 


107.5 


142.6 


132.9 


121.7 


132.0 


115.5 


127,6 


121.2 


121,2 


123.9 


129.0 




132.0 


143.1 


129.3 


129.5 


132.2 


122.7 


123.0 


115.3 


114.5 


126.0 


128,0 


119.7 


104,7 


129.7 


127.6 




119.8 


118.9 


120.3 


121.9 


115.5 


137.0 


129.3 


130.6 


126.6 


124.7 


127.7 


125.6 


119,6 


129.3 


125.2 Gen. at. 



Table XVIII. gives the daily work for C. The first five series represent the 
daily control series. The groups of ten which follow are the reactions with dis- 
traction present. Sound was the first distraction, then light, and finally touch 
distraction. The stimulus was sound throughout the series. Each set of figures 
in the series of five represent the average of 50 reactions; the figures in the series 
of ten represent the average of 100 reactions. The general average of each series 
is given. On account of the size of the tables the tables for the other subjects are 
omitted. However, it was from this and other similar tables that the data for 
Tables I.-XVII. and Figs. 3-8 were obtained. See especially Tables VII., VIII., 
and XXI, for C, and Fig, 5. 



82 EFFECT OF DISTRACTION ON REACTION-TIME 



(N-*C)^^ !>• O (N 0>00i 

-S 2 fO 00 ^i S '^ "55 Ci ;-H (N d 

g (M ^-' (N (N (N IM 

O t-. iO_ O ,-^ <M, 00 fO t>; C<J O 



1 1 



Cl (M "-^ (N (N (N (N 



(N Ci 1-H ,_^ (N 05 i-J '^ (N i^ 

eoGO®>i'%3 <m' c<i •>• i>co>^ 

(M rH JO C<l '-H T-H 1-1 



^. :S 'g -S 

§ O 00 >H ,^ .M GO g Cft O ^. no C<l. '^. 

^ ^ (M "^ ri~ (M „- <N d <N _<¥ <N 

f^ ra _ 

(i* 2 C<J ^^ .2 (N .S <N " 

^ (N ^|J(NjlM|-:i(M>;(M 

s.s<M a^ a ^ ^ ^ 

^-^ -r! (M .a 



1-3 


Tt< 




(M 


d~ 


(M 


.2 














o3 


(N 


^ 


T)H 


-fj 


(M 


02 


(N 


Q 




> -* 




-tj 


CO 


^ 




&c 


GO 



■* s 



(M -R (N (N 



f^c/2 t^iNto^-,, 01 o CO -^ooeo 



c^ (N 



no's cooQo,-^ i-i •* o -^00 oq 



o > 



'^^ i^ 



10 Tf< CD T-H O 

(N (N <N 



feS l>CO©^,-^ Oi <M (N 0OGq<3^ 

r^O,-iMcc<3^Qg o c^ d t-^oo^ 

hh^(N(nS^ CO '-I --I '-• 

(N ^-^ (M (N (N (N 



^ Oi 00 ^ ^-^ r-( TjH i-H '^. ""! '^. 

b-, UjC^OO-'-IS t^ ^ S <^iTl^>~^ 

Ji © T-H Cn t— ( 1 — I O I"! 

O I -fj 

H9 '^ ^ ^ ^^ TD '^ Oi '^ m '^- rf, '~'- '^- ^■ 

rSir«c<iai>-ifc oiTjH (DOS cu'o'^coio^ 

o iX! 02 M ^ 

Ph r— I I— I I— I C^ 

o t^co»c^ £t- 2oo goi'vooojos 

•Ecowo>^o ^jo -gjo -gg ^^"^ 

a M "^ ° (M ,9 <N JR e^ ;*" c<j 



02 



o '-^ O O 
t^Q^-i ^06 <5i2 ^-! "^'-i'* 



<J (M ^-^ (M <N (Mfl(N 



4) 

o 



o 

Ttl i-H GO ^_^ GO CD CD p (N ■~* 

C<io>©i'~' CO oi T-^ CDt>-<30 

IM •-H >2, (M O r-4 ^ 

(M ^-^ (N (M (N <M 



^ 



TABLES OF RESULTS 83 






? i 



Oi |0 



(N 



02 C^ CO <M CO (M 



<1 



'-' ^ ^ 

r-J •<* 1^ 






lO I-H O 



<N 05 li:j ,_^ '-< "i ^ 



05 lO »-; 



<M '2 C^ o "^ C^ 



o cocDf-^i-)ooa!(NH<N ^. "=^?J• 






i I ^ ^^ - ^ 2^ p ?5 p § s ^ - 

S; .9 ^ ^ -3 

^ .. d d -i ^ .a oi J c^ .9 o o ^ ^ 



!2; -El. 

SM :O00©4^ 00 '^i^. ^. 0002 ISO 

HP'S ooco'o- M lo 00 <N-;-t 



O 00 lO CO 

>'-'o^^ o o o o 



gg Ot-00_ CO o ^. i>^f^ 



fe 00 to -* -- 00. <=^. ^ °^ S S 

o 

a 

o 



CO CO •^ "S 
OS rl 

1—1 

H "S ^«-H_„co ^00 ^ ^. ai -i'^^. 



^ o> ^ .2 fc- .2 ^ .g § g _ 

CO -H 

H 



CO CO '54 

o 



o3 02 



f^ ^>OO_2cq'205 2-il_c;cp^. 



a <^ o o o 



CO 00 



° ., ^ao>Ifi~^c6 ^co ^q .j^o^ 



, - o, ^«§ fig «| ^§ 



(N 



«1 ^ ^ o 

g ^ ^ ■^.-, CO 05 oq 

O^CDC0>^?3 CO ^ § 



b- lO "to 



84 



EFFECT OF DISTRACTION ON REACTION-TIME 











CO ^^ 




■* 


CO 




(M, 




T-H 


q 


^ 






-d 

O 





id CO ^ GO 




^ 


0" 




id 




d 


CO 


eo 






1— f 


Tt< I-H ^ 




»o 


CO 




(M 




CO 










^ 




»-H 




T-H 


1-H 




T-H 




T-H 








O 


^ 


























*= 


f^ 




00 Oi ,_^ 




CO 


^. 




CO 




00 


CO 


CO 






o 


05 


t-J id >-J ri 




06 


id 




d 




1> 


1>1 


GO 








tH ,-1 »o 




■rt^ 


CO 




(M 




CO 








? 


•4^ 

-Si 




l-H ^^ 




T-H 


1-H 




1-H 




'"' 








XII 






























■h3 




10 -"H ^_^ 




00 


05 




00 




<N 


CO 


^. 








00 


r)^ t>; ©j --; 


3 


(N' 


CD 




d 




CO 


d 


^ 








1— 1 


1-H 




rC 




1-H 
1-H 




CO 

T-H 










o 











bC 
















cc 




(N ■>* OS ^ 


02 


q 


'^ ^ 


CO 




CD 


q 


-<*• 






fl" 


1> 


c^' ;o ■^' ri 


a 


t--^ 


d 00 





id 




CO 


d 


^ 






.2 




•* 1-1 "5, 


.2 


■* 


IM 


(N 




CO 








EH 

1^ 


'■+3 
o 

1 




1-H 





1-H 




'■+3 


1-H 




rH 








g 






lO (N_ ^ ^-^ 


02 


CO 


-S 00 




l> 







CO 


f^ 




s 


s 


CO 


1-H CO >~H <N 


Q 


CO 


■X 


CO 


t>^ 




'^ 


i> 


GO 




PL4 




rJH ,-1 ^ 

1— 1 


i-H 


Q 2 


s 


(M 




CO 

T-H 








r^ 


43" 






-Td 




TS" 


"73 














^ 


d 






i3 




d 


a 














W 




02 




OS CO 05 ,,^ 



02 


10 


d CO 


3 


t^ 




CD 


CO 


I-H 







id CD ■^ ^2 


06 

10 


CO f^ 









06 
CO 


1-H 


CO 








1—1 




1-H 


'^ 1-H 




T-H 




I-H 








^ 


m 






on 




m 


03 














^ 






:3 




3 


^ 










































g 


3 

.a 




»o ©5 ,^ 


3 


Tt< 


l3 


3 

.a 


CD 




rjH 


l> 


1-H 




^ 


Tf 


oi ci oj CO 


t-^ 


CO 




d 


06 


-<j- 




-13 




Tf* I— 1 "ti 


-P 


10 


-1^ CO 


-2 


C<J 




CO 






1— 1 


1? 
O 


cc 




i-H 


CO 


1-H 


02 1-H 


CO 


1-H 




r-i 






kj 


























X 




73 




CO TjH oq ^ 




10 


C» 




CO 




q 


t^ 


GO 


w 


oj 


'&5 


eo 


06 id >-H CO 




1-H 


,-4 




d 




06 


(N 


>H 




Ch 


OJ 




CO --I >2. 




Tt< 


■rt< 




CO 




CO 








CO 




1—1 




""^ 


1-H 




1-H 




1-H 






S 


h-i 


03 




en r- Oi ,_^ 




CO 


00 




CO 




T-t 


00 


^ 




fa 
o 


(N 


CD >~; CO 




»d 


d 




d 




id 


CO 


GO 









Tji ,-H 10 




■rtH 


CO 




(N 




CO 








H 






rH 




1-H 


T-H 




T-H 




1-H 








O 


> 


























fa 


< 


























fa 


fl" 




■^ '-; ^ ^-^ 




CO 


t^ 









CO 


CO 


'^ 




W 


(B 


tH 


oJ CO ©i CO 




id 


^ 




t>^ 




l-< 


d 


^ 




a 
g 







1— 1 




10 

1-H 


CO 

1-H 




CO 

1-H 




I-H 


































^ 






00 CO Co ._^ 




10 


■* 




to 




IC 


CO 


1-H 




o 




IC 


(m' 00 >h' c« 




id 


CO 




id 




d 


'* 


<3si 




M 


(U 




(M C<) 




(M 


(M 




i-H 




(M 








CO 


.§ 




I— 1 




T-H 


1-H 




T-l 


J 


1-H 








o 


'■+3 
















*^ 










H 


.2 




00 i-j Ci „^ 


m 


1—1 


00 


S 


Oi 


s 

O} 


q 


T-H 


lO 






Ttl 


CO id £? 


'^J^ 


^ 


^ 


flj) 


(N 


1-H 














<N £2, 


CO 


(M 


m *^ 


02 


<N 


p 


<M 










03 
0) 




1—1 


1-H 


.2 ""* 


1-H 


rS 


1-H 










P^ 






"o 






"o 




H 












<« 




■^ lO ©5 ,^ 




1> 


CO r^ 




CO 


-t-> 


rfH 


rH 


f>; 






'E 


CO 


■^ t^ >~; 05 







-3 d 

(-1 '^ 


Pi 



d 




CO 


I-H 






§ 




T-H ^-^ 


U 


1-H 


43 1-H 

a 






1-H 


"o 


1-H 










ic 






^ 




^ 




> 

< 












CM 





00 00 f^ ._^ 


'3 


10 


0^ 


'oi 


Oi 


TfH 


1-H 


^. 






> 


(M 


,_; d »; !2 


Q 


•* 


>) id 


Q 


06 




d 


CO 


>-I 








(M rH CO 




(M 






1-H 





T-H 










<3 




1— 1 




1-H 


03 rH 




T-H 





r-i 










d 










Q 
























P P ^ --N 




10 


00 




00 




1-H 


q 


'^ 






l-H 


CO d -"^I 15 




CD 


06 




d 




1-H 


CO 


1-H 



TABLES OF RESULTS 85 



^ o 





Eh 


•D 




Z 


fl 




H 


:i 




s 


o 




hH 


w 






oT 




PL, 


^ 




S 


3 




H 






m 


zn 




H 






iz; 


02 




l-H 

w 






H 


^ 


1— 1 


^ 


02 
-1^ 


l-H 


iz; 


.22 


^ 


o 


Q 


rS 


H 




r-^ 


O 


o 




1 


^ 


<ii 


P 


d 


H 


o 

H 
O 
H 

W 

W 


o 




O 


<i3 




a 


.§ 

'-+J 




o 


1 




H 


1 

f4 



(N 


CO 


'^ 


CO 

T— ( 


00 


■>-1 


(N 


lO 


i^ 


I— ( 


CO 


>~i 


05 


CO 


00 


GO 

CO 
1— ( 


CO 
1—1 


©i 


1© 


I— 1 


f^ 


(M' 


CO 


©i 



LO rt< ■•--I 



CD 



Tfl 1—* 



to CO t> *-( 



UO >-H -w 



(N 


CO 


O 


lO 

T-i 


d 


^ 


o 


05 


eo 


I— 1 


7— 1 
1— 1 


©i 


o 


CD 


©:> 


lO 


>-i 


■si 



Ttl T-H l-H 



,_( CO !>• ■^ 1>. 



CO ^ 


<to 


lO t>^ 

I— 1 


^g 


00 lO 


^^ 


I— I 


"" s 


CO (N 


oq ^ 


TjH 1>1 


■^ O 



> 


C<| lO 00 ®4 (M 

C^ t-H 


s 




0^ 

o 


'^ "^ °^ ^-v 


,-< r^ CO -^ CO 



86 



EFFECT OF DISTRACTION ON REACTION-TIME 











^ 00 SO jr- 
»n lo ©j CO 




CO 




CO 




(N 




CO "* >H 






rf3 


o 




ci 




VJO 




(N 




CO (N to 






U 


1—1 


(M .-1 ^ 




•* 




1—1 




1-H 




(N l-H 






^ 




i-H 




1—1 




1— ( 




y-i 










o 
























Cq 


H 


























(h 




■^^ °o '^i. c;" 
CO CO ■^' CO 




10 




00 




CO 




(M 10 to 




o 


o 


Oi 




d 




CO 




(N 




(m' id Jv 




c 






(M <-! ■^ 




■* 




1— ( 




1-H 




(M 1-H 




^ 


5'" 




7—1 




1— ( 




T-H 




1-H 




1-H 




S 


bO 
























02 


P 




P 9 ^ S' 
oi c<i >-H CO 




10 




1—1 




CO 




CD 10 to 






-§ 

3 


00 


t3 

3 


id 




id 




1-J 




d d -* 








(N 1-1 ^ 


CO 


'5> 


1— ( 


^ 


l-H 




(M 








>-< 


1—1 


1— 1 





^ 


1-H 




>— ' 






o 






o 




bO 














CO 




-*' CO >-^ ^ 


cc 


CO 


3 


1—1 


H 


10 




CO CO »Q 






.§ 


i> 


c" 


d 


fl" 


■* 


iJ 


id 




CO -H IQ 








(M 1-1 ^ 


o 


■* 


.2 


T-H 





l-H 




(N 1-H 




1 


'-!3 

2 




1—1 


'■+3 




'■+J 


2 


1—1 




o3 


1-H 




T-H 




1 




CO 


""i '-; '^. S" 

lo lo ©i CO 


CO 


d 


_0D 


CO 

d 


2 






tH t^ ?^ 

CO 1-H ui 




P^ 




(M .-1 Si 


>* 


P 


I— 1 


P 






(N tH 




PM 


• •. 




1—1 




1—1 




l-H 


l-H 




1-H 




>i 


•ia" 






43" 




•13 




^3" 










fii 









d 









a 










m 

EH 


3 
o 




■># l> Cs Q 

^ ^ ©J CO 


3 

02 


05 





(N 


5 


CO 




rjt CD to. 




in 


1—1 



02 


id 

1-H 



02 


CO 

1-H 




CO id t>I 

O^ l-H 








1—1 




1—1 




1-H 




1-H 




1-H 




s 


CQ 






m 


















^ 






3 




^ 




^ 










3 

a 




CO o> ©4 ^ 
C^ lO ijci CO 


3 

.a 


CO 


3 

.a 


CO 


3 

.a 


05 




"<j< 


hH 




^ 


■* 


id 


06 




ci ^ t^ 


1— 1 


;5 




(N 1-1 <-> 


'+j 


■* 


-13 


1-H 


'■*-> 







IM 1-H 


1—1 


12; 
o 


cc 




1-H 


02 




c/i 


1-H 


02 


1-H 




1-H 


n 


























m 


0^ 




1-1 (N -^ ^-, 









Oi 




(M 




q CO >H_ 


f^ 


*S 


CO 


i6 lo ©i "5 




T-i 




•<i5 




(N 




CO <m' to 


3 
< 


CO 




IM rH CO 




1— ( 




1-H 




^ 




(M 1-H 

1-H 


H 






t-; ^ 130 ,^ 









CO 




"*. 




(N 1-1 ^ 




f^ 




c^ 


c^ o oi JO 




(>> 




d 




I>^ 




d id t-I 




o 


"o 




(M 1-H CO 




rj< 




1-H 






1-H 




(M 1-H 

1-H 




H 


> 


























-^ 
























t 






1-H T|H I-H ,_^ 




■*. 




00 




00 




OS o:> 






1--( 


CO ic ©i ^5 




1-H 




d 




d 




T-H (N to' 




o 




(M 1-1 CO 




'^ 




1-H 




l-H 




C<) 1-H 








1—1 




1-H 




T-H 




1-H 




l-H 




























E-t 


























1 






(N (M, Vh ^ 




CO 




t^ 




1-H 




00 05 Ob 






lO 


ui i> 1-^ o 




06 




d 




ci 




(N CO '-i 




0; 

a 




1-1 ri 
1-1 — 




1-1 




1-H 





1-H 


tn 


l-H 

tH 




o 


1 


















« 






H 




00 Oi to ,_^ 




»c 




!>. 




^. 


'% 


05 00 »-H 






*■§ 


^ 


t>; t>; >.; CO 




■«d^ 




ci 


00 


t-^ 


m 


(m' d &0 








1-1 ri 




(N 










0) 

0) 


1— t 






§ 




1—1 


S 


1-1 


s 


rH 


"S 


l-H 


r-H 






fS 

o 




■*. t^ to. ,-^ 


02 


00 




IM. 


02 
3 


Tj^ 


^ 

^ 


00 i> oq 






t 


CO 


CO l> 1-4 CO 

1—1 ' 


"o 


1—1 


3 


CO 

1-H 
1—1 


§ 


l-H 
1-H 




06 id ©i 

1-H 






M 






a 





a 










3 








O 




CO »o C) .^ 





1> 





1-H 


^ 


05 


> 


OJ t^ ©i 






t> 


(M 


CO 05 ©j «o 


>> 




>, 


d 


■3 
P 


8 


< 


d 06 ^ 






<J 




1— t 


■3 


1-1 


■3 


1-H 


1-H 


a 

0) 


l-H 












n 




P 














S 



























O 




T-H O •^ ,— ^ 




CO 




CO 




10 




(N 0> t>; 






y—\ 


"^ d ©^ 5 




d 




d 




CO 




d d 90 










iM ^ rl 




CO 




1-H 




1—1 




<N 



TABLES OF RESULTS 87 



-fSor^It^I^co oJ (N CO oeo 



05 ^ 



^^^^ ■* «> "^ '^'=°. *^. 

;-;>^o:) i^ CO 00 t--oo 






cDiof^^ »o CO 00 ccoqoq 



T3 00 t> 03 



ICI 04 



o -d -u "g 

T-. 00 -* ^ g o .y) t-: o CO ^ ^. (N o 

^ M *43 -t^ +? <u 

«Pco2cJ>;g^co^^^|gS^- 
K3 H .^ .~ •- "ts 

, S lOCOQO^'OoO'St-'^'-i.-'N. « ^. 

I 4 »s2~g is §5 is "s"^ 

^ a (Nt-:0i^^0q^':t<_500flO'# 






<) a> CO "^ ^ 



02 02 02 

COOO^ ^ o= ^ ^■*. '^. 

C5>^'* »0 00 '-I C0CO20 



<1PQ i>coo5^ CO »> »>: <©. f^^ 

H h«<-/vidrH>s'*' CO 00 CO 05I>-S^ 

. ^ ^^ ^-H tH T-l --H 

O <!* 

fe fl CD O J^ ^ <N <M. ''^l =0 -* CO 

f^ (U . ^-i r-^ -^ ^ oi CO "-H ,-(lO<^ 



5^ 00 cr> -^ ^ -^ <M. P '-I «=. ®^ 

|^vocjco>^o ^ g t:^ ^i^^ 

- •••— oco oo a^»o ^cot-iO 



CO >o 



S 02 CO cc ^ 

-a cot^^-;o -go ^r:- 12 :S^^^ 



ooco^^^co:3^. ^oq >oqcq'3* 



<3 ^ ^-^ ^ .-H ,-ljjr-( 



O 



O 

05^,-, •* 00 t- '^. <^. '^. 



88 



EFFECT OF DISTRACTION ON REACTION-TIME 



X 



o 


><1 
















S3 


02 


!S° 




^ oq O Q Eq fc< 


^ 


(D 


3 














TS 


3 
















H) 


o3 
















^ 


H 






(N 


t-; 


CD 


(N 


1-; CO 


C^ 


Q 




o 


CO 


^ 


>o 


CO 


>o t> 


^ 






l-H 


(M 


1— H 


Tfl 


Tt< 


C^ 1-1 


u 


'5 






IM 


(N 


^^ 


1-H 


1-1 1-1 


o 








I> 


q 


o 


(M. 


q lo 


^ 


-fi 


o 


im' 


lO 


t^ 


l^ 


CO i> 




fl 




(N 


I— ( 


TjH 


CO 


(M 1-1 


CO 

o 


.9 


lU 


00 


CO 




1—1 

q 


1— ( 

Oi 

00 


T-l TH 

O CD 


o 


cc 







(M 


1— t 


rJH 


CO 


C^ 1-1 


> 


;3 


.2 




(N 


IM 






T-t 1-H 


03 


O 


'■♦3 


















s 




O 


CO 


C^ 


q 


lO T-H 




t> 


ci 


d 


(N 


(N' 


T)H 1> 


;^ 


OQ 




(N 


T-H 


'^ 


•* 


(N 1-H 


P^ 


s 




(N 


(M 


1—1 


1-1 


1-H 1-H. 




03 


rg 




CO 


U5 


iq 


lO 


1-1 CD 


> 


^ 


■& 


o 


(M 


(m' 


1—1 


^ 

^ 


id 03 

C^ i-H 


1— 1 


o 






IM 


(N 






1-H tH 


X 


13 
o 

-4-3 
















X 






CO 


lO 


Oi 


»o 


"* "? 


^ 


"*f 


iCi 


(M' 


1> 


»o 


CD 


IC i-J 


o 


O HH 


g 




c^ 


o 


•* 


Tf< 


<M (M 


.2 




IM 


<M 


1—1 




T-H TH 


-»J 




v> 














X 


-S, d 


o3 




'* 


t>. 


q 


<N 


CO (M 


•^ ^ 




rH 


d 


d 


ai 


l-H 


(m' d 


1— 1 


^—1 




1— 1 


o 


Tf< 


»o 


(M <N 


M 


^ 9 


'o 




(N 


(M 


'"' 


'"' 


T-H tH 


M 

^ 


1 g 


> 


CO 




CD 


CO 

00 


o 
ai 


T-H Ttl 
id CJ 


3 

03 




C^ 


O 


CO 

1—1 


i-( 


(N i-l 
I-H 1-H 


H 


CO 

c3 


o 




o 


00 


Oi 


q 


l^ l^ 


t«-l 




C<1 


I> 


i6 


d 


"O 


(N d 


o 


rt 






T-H 


o 


-* 


Tt< 


C^ (M 








(M 


(M 


1—1 




1-H tH 


>1 


O 


















*-+3 






N; 


O 


"* 


lO 


^ CO 


a 


o3 




1-1 


CO 


(N 


OJ 


CO 


CO in" 


f^ 






(N 


1— ( 


Tt< 


>o 


(N 1-H 


a 


02 






(M 


(M 


1— 1 


1—1 


1-H tH 


;3 

CQ 


^ 
















03 


0) 


O 




05 


00 


00 


CO 


(M 00 


^m 


.a 


lO 


c<i 


CO 

02 






id (N 

rH 1-H 






-f3 




(M 


T-H 


T-H 


T-l 


1-H T-H 


O 




a 














fl 


.2 




CO 


'^ 


00 


00 


00 CO 


'a3 


o 


'-13 


■* 


(M' 


tH 


CO 


'^ 


i>I CO 


^02 






1—1 


o 


(M 


<N 


I-H T-\ 


X2 


'S 




(M 


(M 


1—1 


I— 1 


1-H I-H 




03 


P5 














hH 


a 


Q^ 




l>; 


l>; 


-* 


CD 


■* °°. 


> 


a 


"ft 

a 


CO 


CO 


3 


TJ^ 


Tt5 


00 t>^ 


X! 




1— t 


o 


(N 


(M 


r-H 1-H 


o 




(M 


IM 




1—1 


1-H 1-H 


X! 


*1 1 


j« 
















o 


«« 




lO 


1^ 


00 


q 


CO 00 


<D 




o 


C<l 


lO 


00 


^ 


lO 


CO CO 


03 


^ 




(N 


1—1 


1-i 


(M 

rH 


C^ 1-H 

1-H 1-H 


H 


& >^ 


d 




Tf< 


tH 


O 


q 


1-! q 




S o 


d 


1— 1 


C^' 


CD 


CO 


T— 4 


TjH i-I 




O 




C5 


O 


C^ 


CO 


(M (N 




ft -tJ 




(M 


IM 


1—1 


T— 1 


T-l 1-H 



TABLES OF RESULTS 



89 







CO 


■^ 




;^ 


-<:t< 


t^ 












^ 







05 i-J 
CO 1> 



I I ^ 









(N CO 

CO CO 

O O 



CO GO 
00 --H 
O O 



t3 

d 
o 












CO 
CO 



iq 00 

CO T-H 



Tj^ CO 



1-h' 00 



a 
o 






S CO b- IM t-i 
r'^ --I O .-H (M 






03 
O 



00 CO O 00 lO ■* 
t^ t^ rt< CO t^ r-4 
O O O O O --H 



no O lO O 

CO -* 00 CO 
o o o o 



[^ i-j Tj^ CO T-j irj T-j 

• IQ CO CO CO 05 o 
Qh 1-1 



S. »0 (N O lO 1-M CO 



IS! 



O 00 rH 00 •* CO CO 
lO O O" CO' (N CO (N 



00 •^^ 00 U3 IC iq ■>* 

OJ 00 00 i-J CO i-H CO 
1— t rH CO T— I T-l 



CO lO 



CO Tj< .S 



a 


?i 


•+J 


rt 


^ 


o 


o 


rt 


-fJ 


«3 


rt 


^ 


O 


-(-> 


O 


CI) 




;h 


(U 


n 


•a 


a 


m 







O) 


O 





03 o3 



TH >— I O Oi rH O 



tH »H CO rH O i-H 00 



■^ 


S 


1-H CO 


^ 


,—1 


CO 00 


TJH t^ 


lO 


■* Oi rt< CM 


^ ^ 


cc 


a> 




CO -^ 


(M 


^ 


r-l CO 


o t^ 


C^4 


CO O CO CO 


CM O 


o 


o 




Eh 


(M CO 


CM 


CM 


CM CM 


T-H 1-H 


CM 


rH 1-H i-H 1-H 


1-H CM 




<<, 




* 
















i=! 


ro 






aj +s 


OJ 


-a 
a 

o 

CO 


n^ -^ 


a> <D 


T3 


j3 


O o 






fcn 


CO 


1'^ 


o 


O o 


o o 


O M O O 


O o 


^ 


03 




Ci 


!5 K-5 


;2; 


^;h 


^ ^ 


^ ;3 ^ H 


Iz; H 




^ 


i 




















a 


H 


1 




















■+J 




s>> 




















ri 


4^ 


^ 




















.2 

H-J 
O 

c3 
O) 
(h 

H 


o 

c3 

<U 

d 




s 

•^ 


-1-= 


- 


- 


- -- 


T3 


3 :: 


;- 


- ;. - - 




* 


:S 



OQ hJ 



90 



EFFECT OF DISTRACTION ON REACTION-TIME 













tH tr- 


o 


00 


(N q 


t^ 


1> 


1-1 o 


•T3 












t^ 


i-i i6 


im' 


lO 


ca d 


00 


oi 


d 00 


O) 










00 




1— ( 














■73 










CO 


^ 


1 


1 


1 




1 




1 


^ 








( 


■^ 

^ 
























o 




•S 




lo a 


CD 


o 


i> r-; 


o 


CO 


(N l> 


73 






? 




;:5 


1 


»0 (N 


C^ 


CCJ 


oJ c5 


00 
CO 


00 


°a 


i 






tc 






&s 




1 




1 1 


1 






^ 
^ 
'« 
^ 












o 


o r^ 


CO 


CO 


CO (N 


05 


(M 


2 o 














t^ CO 


(N 


CD 


•* 1^ 


00 


■* 


;S^ <N 


(U 












a^ 


q q 


q 


q 


q q 


q 


q 


q i-H 


•S 








>^ 


























, 




















o 








^ 




















^ 








^ 




Eq 


CD q 


>c 


•* 


o t^ 


Tt< 


CO 


O CO 










"So 




c^ 


»0 CO 


c<i 


»o 


(N CO 


CO 


(N 


(N d 


bO 








ts 




















rt 




































fe. 




^ 


CO (N 


CD 


1-- 


O C5 


<M 


rt< 


q t>: 


'o 












^ 


i6 00 


i6 


^ 


CO c> 


lO 


CD 


O lo 


t4-l 












y-l 




I— I 


I— I 


T— 1 




'-' 


g 




























• 










w 


CO ■^ 


»c 


q 


1-H CO 


'i* 


CO 


"5 (M 


*-+3 
o 
c3 


to 

;3 










^ 


1^ i> 


1—1 


oi 


r^ —5 


d 


d 


1-1 lO 


h 


to 










e 


O y-* 


T-H 


1— 1 


CO 40 


t^ 


'^tH 


1-1 iM 




o3 










(N M 


<M 


<N 


1—1 i-H 


1—1 


1—1 


T-i 1-1 




^ 


)—t 
























-1-3 


'^ 


^ 
























^ 


.2 


M 
























^ 


*r-i 


s^ 








Ci 


00 CO 


C^ CO 


(N lO 


■* t^ 


Ci 05 


Ttl 1-1 


CO t^ 


*+H 


a> 


rS 








^ lO 


rtH -H 


^ CO 


CO t^ 


CO TJH 


^ o 


:2: '^^ 


m 




X 








a^ 


q q 


p '=; 


q q 


q q 


q q 


q i-H 


q q 


w 
























-f^ 


i=! 


3 
























, 


O 


^ 








6q 


q lo 


l>. CO 


!>; q 


00 o 


CO Tt< 


q lo 


O CD 


o 
o 


id 










i-i CO 


CO "-J 


CO CO 


T)^ CO 


CO (N 


,-H »0 


(N (N 


H^ 










ft^ 
















o 


o 

a 










li^ 


q q 


00 q 


00 05 


(M 00 


o >o 


ic 1-; 


Tj; (N 


.2 












^" 


CO CO 

I— 1 


00 CO 


00 00 


00 i-i 

I— ( 


oi CO 


io d 


IC t^ 


.2 


























o 
c3 


& 










<i> 


00 CO 


Tjl © 


Tl< C5 


rJH O 


00 Tt< 


i>. q 


1> 05 


^-4 








Q 




•c* 


(N O 


CO 00 


CD i6 


l^ (N 


ai (N 


CO l>^ 


d d 


m 


<U 










o o 


O (M 


(N »0 


(N CO 


(N »0 


1-1 lO 


^ 


O 






' 




E<i 


?« (M 


(N (M 


(N (M 


1—1 1—1 


1—1 1— ( 


1—1 1— f 


rH 1— H 


0) 






.^ 






^—^^ 


~ ' 


"— ^^ 


^-^-^ 


^— V— ' 


^^— ' 




O 


fl 






ts 






* 














fl 


s 






g' 






a> if 


<D '3 


« o 




<» 12 


0) y 










1 




■•o 


C -a 


G S 


d g 


1=! -£ 


Pi S 


CI 3 










•«2 


o W) 


o s 


o o 


O bC 


O O 


^ o 


a 


CQ 








"^ 


^. H 




^H 


^ H 


^H 


1? H 


■-3 






ft. 




















*-(3 

.2 

o 
as 

-a 


o 

d 










s* 


-4-= 
-Si- 












S - 


* 














bC V. 










o " 














^ 


3 






o 
in 








'^ 



TABLES OF RESULTS 



91 



O 



.1016 
1^ ^<N 



CO CO 



i-H (M (M 






CO t^ ^ 



CO CO t^ 

CO TtH ■* 

00 o 



§ 
















1 
















Bq CO 


CD 


CO 


Tf 1-H 


(M 


1-H 


10 1> 


CO 


Q^- CO ^ 


rH 


(N 


l-l (M 


IM 


<N 


(M i-i 



t;^ (M CO 



Oi 00 
CO >o 



05 i-H 





(N 


00 


1> 


(N 00 


t^ 





1-H 


00 01 

00 05 

T— 1 I-H 


1-H 




»0 00 
rH 1-H 


1-H 


(M 

1-H 


00 

1-H 1-H 



CO 00 »0 00 o ■* 

_ 01 1-H O t^ 1-H 1-H 

Q,^ O T-H O O O T-H 



o 



Tt* O CO (N (N CO 
10 03 (M CO CO rH 
O O 1-H O O i-H 



Kj <N CO 00 p O CO 
P_J CO J> O "3 T-H 00 



oi t«. Tt; CO CO c<j 

1-H Tji oi ■<* <m' O 



CO (N 

00 00 



[:^ p CO tjh CO I-H (N 



p t>; P !>. -"tl Tt< 

I> oi lO 1-H T)^ t>^ 



rH 00 
CO rH 

CO CO 



g OiCO»OcO»-HOi OOOOCDOO-* 



O t^ CO 00 (M rH 

•J^ '^l TjH rJH C3 O 
(M (N (M C<l rH C^ 



C5 CO 00 CO CO 05 
CO O <M 00 CO TfH 

rH (M rH rH rH 1-H 



■s § 1^ § g § § 



o 2 o +; a> o 

fl § (3 -f! C5 S 

3 O ^ .bC o g 

;? 02 Iz; h:] 12; H 






GQ fj 



X! 

3 



92 



EFFECT OF DISTRACTION ON REACTION-TIME 






^ 



S (N 



CO CO CD 
O O -^ 

o o o 



CO (N 05 
t^ rJH <M 
O O i-H 






»0 !> 

CO >-! 






CO 



CO 

CO 



<» ■>* CO 
E-( --I C^ 



CO O O 03 CO t^ 00 
CO CO I-H CD CO 00 CO 

O .-H o o o o o 



05 O CO O CD CD 03 

CO CO o CO CO 1— I CO 

O O rH O O O O 



i-H -^ CO 

■* o -* 

1-H O O 



• 00 Id 05 (N i-t CO i-H 
*^. -^ O O CO CO' I> CO 

, (N T-1 



T-H CO »0 <N (N CO CO 
■^ -^ •<* (N Tj^ r-J CO 



1> rH i-H 

>o d (N 



•<^ t^ O Oi lO CO lO 
00 Tj? (N (N CO CO 00 
>— I CO ■^ 1— I i-H 1— I 



q 1-1 CO CO Tt< (M 00 
co' 00 i>^ ■*' i-H (m' c<i 



cii i-H q •* ■*_ CO •* CO 

S lo ko id CO ^' co' CO 

•ci t^CDOi00O5G0'-H 

b-l lMlMC5'-HrH,-HC<J 



CD "* !>• ■* CO 05 ■* 






Pi 3 



d § 
o ■? 



O .bC o 



^_ ^ ;^ ^_ jg ^_ H ^_ ^_ S ^_ ^_ ^ H 



O) OJ o 

fl el 3 

o o o 

15 ^ H 



OQ 1-1 



TABLES OF RESULTS 



93 



Bq 



Sc! 



CO 


N 


T-( 


00 


i-H 


00 


o 


CT> 


CO 


IM 


t^ <^ 


rt< 


CO 


o 


rJH 


T-H 


Tt< 


-■IH 


(M 


lO 


:^ 1 


1 








1 








1 


^2 


O 


o 


o 


i-i 


o 


Tt* 


CO 


1—1 


1> 


r-t 
i-l 


t- 


00 
I— 1 


o 

CO 




CO 


00 
CO 


CO 


o 
CO 



o o o o o o 



o a> 

00 Tt< 

o o 



Bq 00 oi CO 05 1-H 00 

0^ --J (N ci O tH (N 



CO CO 

CO T-H 



CO <N 
CO (N 



^ CD CO 00 00 
lJ O 00 t> (N 



CO ■* 
CO 00 



00 lO 



00 CO 



lO Oi 00 "* 


"* (M 


t> CO 


CO lO 


TtH lO 1> CO 
1> C2 05 03 
1— 1 I— 1 rH I— 1 


1—1 r)< 
1-1 (M 
1-1 i-t 


lO .-1 

O 1-H 

I-l 1-1 


CO CO 
1-1 CO 

I-l I-l 



rjcOT-icoi> cocooot^o 

.i-i(MiOi-i lOt^i-IOOCO 
a^OOOO OOrHOO 



t^ o 

o o 



IN CD lO CO 
rH i-H CO <m' 



»0 Tj< T)< CO 00 
(N im' l6 I-H CO 



(N Ttl 

Tt5 o 



ta-COriHO>CO rJ4<ocqkOT)j »OC^ 
(^CO-^OCO l>cd-*(M'o T-ii-H 



•^0500'^ lOc<icqi-HCO l~-;(M 
CD CO ■*■ I-H i-I CO CO CO 05 CO -*" 

~~— TjHlOIMTtHTfH lOCO 



. Q, ^J -O -^ 



CO H 



a1 

o 



9^ If O « 



o 5 o .=v b o o 
!^ cK 12; H^ E-; I? H 






CI 

o 

CO 



94 



EFFECT OF DISTRACTION ON REACTION-TIME 



^ c6 t>. 



CO t^ 


(M O CO CO 


CO CO 


CO (N 
I— 1 

1 


tCi CO O (N 
1 1 


rH o 
1 



1-s 



00 


Oi t^ 


T-i r- o ■* 


H CO 

T-( 


■* o 


CO (M CO ^ 
■-H (N ■* CO 



*-l 


a.' 


CO 
o 


00 

o 


CO 
(M 
O 


■* 


CO 


CD 

o 




o 


q 


I— 1 
CO 


1 


e4 


lO 


(N 


CO 


CO 


1-H 


»o 


o 


lO 


Oi 


lO 


CO 


Hh 


(M 


»o 


I— I 


>o 


CO 


■"* 


c^ 


T— 1 


T-( 


lO 


s 
























t** 


t-' 


CO 


(M 


(N 


lO 


CO 


05 


lO 


t> 


(M 


CO 




><!S 


CO 


rJH 


lO 


»o 


00 


■* 


»o 


lO 


lO 


t^ 



t^ 00 05 Cs 1-1 o 



.g CO ■* -^05 
|£ --H Tt< (M CO 

" (N (N (N (M 



CO CO ^ lO •«# r-H 
<N CO (M CO rH CO 



^ 2 ^ H S 2 

Qs* "" ^ "" '" "" 



IM C» --H O l^ 
(M CO CO t^ 1> 

O O O rH O 



l^lj" p (M_ CO CO CO 
?: Ti^ t>; CO lO TtH 


--H O 05 00 


CO lo 


l-H Tt* 1— 1 ^ 
T-H 


CO (N 





t- 


j> 


CO 


l^ 


00 


00 


1— 1 


a> 


(M 


CO 




^ 


o 

r— 1 


(M 


O 
I— 1 


00 
I— ( 


T-l 


CO 


o 
I— I 


»o 


00 
(M 
























fi 


S 


1— 1 


OS 


t^ 


CO 


lO 


O 


CO 


rH 


rt< 


S 


00 


o 

CO 
(M 




C5 

CD 


(M 


o 


CO 

1—1 


CO 
I— 1 


CO 

CO 
I— I 



00 t^ 

CJ CO 



C5 ^_ q ^_ eg H ^ cK H ^ ^ ^. 

&3 iJ iX! H 



TABLES OF RESULTS 



95 






t^ tH t^ t>. 



Tf CO CO ^ 

lO rH CO CO 



t^ CO 

<N d 



1.1 



00 Oi O 00 


(N CO o o 


(N 05 


t^ lO 00 o 

T-H C^ I— 1 I— 1 


O Oi O) CO 


l-H 



(N CO O lO lO 00 

- . . CO O CO O T-H TJH 

oooo oooo oo 



taqcocoi-;(M_ cq-^oio oop 

fl_j >-( CO O (m' i-i -^ .-I CO d CO 



O 1-H 05 lO 


lO 0> »0 Oi 


(N 00 


CO 05 CO o 


Tt< (N TtH 05 


(M 00 



«oqic(M_oq ppi>;(N i>:ff^ 

,§,-Hoido6 dcoooc^ dci 

C^O'+ICOIM COOiTjHiO cooo 

tH<M(NIM(M i-lT-ii-HrH 1-Hr-l 



lOOCOCO COOOOSi-H CO(M 

oooo oooo oo 



K3 



CO l-H Oi r>; 

U3 -^ d d 



■^ ■* '^ "* »^ fO 
CO lO Ci Tji lO CO 







CO 


(N 


CO 


(N 


05 


1> 


00 


o 


O r-4 




-* 


I— 1 


00 
rH 


00 

ft 


05 


T-H 


l> 


CO 


I— 1 


5^ 






















«J 


5i5 


CO 


'^ 


(M 


CT> 


o 


(M 


l> 


(M 


O CO 




1 


05 

I— 1 




LO 


Oi 

CO 

IN 


o 

l-H 


CO 


T-H 


o 

CO 
i-H 


00 Tf< 
1-1 r-l 


fc-H 
1 


CO 


o 


3 


13 
PI 

:3 
o 

02 


o 

o 


c 
o 


O 
02 









• T3 






:: 3 
o 


GQ 3 


Oi 



96 EFFECT OF DISTRACTION ON REACTION-TIME 



H^oJod ci cooed oJ>oco«c5 



^ 



^ 



>-<CD CO l>(Ni-l OOOiCOOO 



cc 6 I I III 



'Q*f-?S"*05 O OCOCO (MCOCDOi 

'5^-§'~'fO T-H CO CO r-H 



^ 




o 


00 

00 

o 


q 




■* o 

I— ( 1— 1 


O O 

q q 


■* CO 

qS 


4 


















1 


















S- 


fiq 


CO 


l> 


CD 


to 


(N CO 


IM CD 


i-H t^ 


"« 


Os 


I-H 


05 


■<n 


CO 


CD 00 


T-l r-t 


CO ^ 



»0 (N 


■* 


"* 


a> <N 


■* TfH 


■* I> 


CO CD 


1— 1 


Oi 


CD CO 


CO ■* 


00 ■* 



■* 00 


(N 


05 


(N CO 


CO O) 


CO 


CO 


Tt< CO 

lO t^ 



(—1 

n rjooiooioiot^cot^-^cDOco 

f^ .OSt^cD-^CDOJ TfiOCOOOcO COtO 

jxj ft^qqqqqqorHoqqqq 
W 

2 I«5TiH.-ico»oeot^c<jqt*oocoqq 

^ ft_jo6cDlCCO"3l>N"5.-!'^CO'-!'^ 







t* 1-1 CO CO CO t> 


i-H UO O OS 00 


lO Oi 




<N 00 ->* OS ■* (N 
(N rt i-H .-1 (N 


CO CO U5 (M CT> 


1— I 


«^ 











Q> CO OS T-H d 1-H »— t 

S i-H lO OJ oi OS 00 

• ^ lo lo 1— I CO ^ CO 

6*1 <N (N (M (N (N (M 



(N 


t^ 


OS 


o 


00 


OS 


i-H 


OS 

CO 

T-H 


OS 
lO 


CO 

CO 


I-H 


1> 

I-H 


1-H 


CO 

00 
I-H 



!:&. = = = . 1= . = . §. 

6Q h^l 02 H 



-r! ^ T-! Jd Jd 



(N 



bD 

_o 

O 

o 

ai 

3 

Q 



TABLES OF RESULTS 97 



!^ 



^ 





(N 


Tt< 


CD O 


(N 00 (N Tj< 


(M CO 


1^ 


Oi 


l> 


r-l O 
I-H 


«o O O 1> 


»0 00 




i-H 


IC 


lO 00 


O ■* rt rf< 


C<J (N 


;'» 


00 
1— ( 


o 


1— 1 


CO CO 00 lO 
tH rH (N 





9 



^ CD 00 

■^^_-i^ OCOfOCC »OC^ 
ft^OOOO 1-HOOO oo 



i 


&:;■ 


»o CO ■* 


OS 


05 O (M 


t^ 


05 00 


CO 


Ch 


(N IQ I-H 


r-( 


■* (N <N 


Tf< 


(M .-< 


^ 
















^ 


00 CO CO 


(N 


U3 t^ rH 


O 


OS OS 




:» 


CD rti ■<*< 


lO 


l> 00 CD 


•* 


I> ■* 



•^ fc t' *5 5 C<i d i-H 00 OS oi 
E-<?3feSS t^c^ooco coco 



►^ ^^J???'^ '^^OrHO (MOO 

„ DsOooo i-HOOi-H oo 



[jq>ooc<icq oiot-hoo ooos 

• ^ CO (N lO od CO Ci CO tH' rtJ 



O O OS CO 


l^ IC CO TtH 


--( (N 


CD T— 1 »o »0 


CO OS CO —1 


CO CO 



(M 1— I i-l 



o- •§ 2 £2 '^2 1^ lo" cd' OS ■*' o' rH 

^, E>(;::3SS5SS r^coosos ooos 



^ Sill s|s| §1 

•2 o .^ § § I g M g I g 



. -f^ '2 ^ 

S -^ ^ ^ ^ 9 y 

^ ;3 eg ^ 



98 EFFECT OF DISTRACTION ON REACTION TIME 






:^ 



>§ § l^ O CO 05 (m' lO 
_ "O S (N CD --H <N 

oi e I I I I 



SOSfNCD'-H <N --^ C^ 







o 


1:^ 

■rtH 
O 


O 


q 


q 




CO 


1—1 


CD 

q 


05 

q 


GO 
























.« 
























'=^ 


&q 


i> 


1—1 


rt< 


(N 


■># 


lO 


CO 


lO 


Oi 


l-H 


00 


ft^ 


■* 


TJH 


CO 


^ 


<M 


o 


tH 


00 


(N 


(N 



























03 (N 00 lO 


t^ U3 CD CO 


O CO 


CO i-H C5 tH 
1-1 1—1 tH 


I> lO CO 00 
1-1 (M 


00 ICl 



hJ 




X! 


O 


H 


(1. 


i-:i 




w 




-< 




H 






t^ 




a. 



I^ ^ ^ "" ^ 



itoqtNoqq icqco(N q-^ 

SiOCOt^r^ TtirlHi-ioJ "^CO 

I'^i-iCO'Mi-l COOiOiO <N^ 

C-I(N(M(M(M i-ii-irHi-i i-ItH 



t^ M <M CO -^05 

.,. GO(NCDt-( COiO 

OOOO Oi-iOi-( Oi-i 



>0 O CO t^ 


CO i-f CO ■* 


00 ^^ 


CO 1> '^ (M 


rlH t^ CO lO 


CO 05 



Oooi>Oi qoqi>q wq 

rH CO (M' t^ 



S <»(Ml>O5(NlOl>;0qt> 

i2 So6cdcot^«ooT)Ho6 

75, r'^OOOli— lO COCOlCtTjH 

^-^ C:-(i-i(M(N(N i-(i-(i-li-l 



^_ ^3 CO H ^ CO h^_ H ^ H 



• • • • 73 rd 

&a 1-5 CO t-" 



TABLES OF RESULTS 



99 



t- 






o lo 

CO (N 



NJ 






1— I T-l Tj< CO 



t^ CD l> 1-H 





O 


CO CD 


t^ 


o 


Ttl O Tf 


Tt< 


CO 


O 


o 




l-H -"^ 


CO 


t^ 


TT< CD TlH 


CO 


Tt( 


<M 


CJ 




a^ 


P p 


q 


q 


a> <^^ c> 


q 


q 


1— ( 


o 
-a 

o 




















OQ 


^ 


M 


CO t>; 


(N 


CO 


lO 1> lO 


I— 1 


CO 


l> 


^ 


CO 


Os' 


T-i •>* 


CO 


CO 


ci CO (N 


1—1 


(N 


CO 


3 


?-* 




































'■+J 


e 


















m 


s 


















<o 



lO 


00 


CO 


O 


I> 


o 


T)H 


(N 


■* 


00 





CO 


CO 
I— 1 


02 


00 

1-1 


CO 


o 

1—1 


t^ 


lO 


CO 


03 
l-H 






















^ 






















1 


05 


lO 


CO 


00 


05 


CO 


I> 


(N 


1> 


CO 


■a 








1—1 

CO 


00 

1-1 


00 
I— 1 


1^ 

CO 

1—1 


i-H 


CO 
CO 
1—1 


CO 

1—1 


'qS 






Eq 



CD Cft 00 O 
CO 00 ^+1 »o 

o o o o 



■* t>. (N q 

CO 00 ■<* '^ 



(N ■* 00 CO 

CO CO 00 CO 
o o o o 



CO CO CO CO 

CO ■* iri c<i 



CO rt* 

rH O 

^ o 



t>: CO 



yj CJ CO i-< 1— I 



05 CO (N OS 


«*f CO 


05 CO ICi CO 


05 1> 






00 -^ (N lO 



CO r^ ■* CO 



o 


C<1 CO <N 
CD CO CO 
(N (M IM 


05 O l-H 00 
lO CO !>■ 00 
tH ,-1 1-1 1-1 


CO 00 

1-1 T-1 




PI 
o 


Light 

Sound 

Touch 


None 
Sound 
Light 
Touch 


O o 


03 

.2 

'■+2 



-a 

3 



£>2 K^ 



n3 

3 



tsj 



100 



EFFECT OF DISTRACTION ON REACTION-TIME 



05 l^ •* O GO IM rH 





o 


h^ 


05 


h- 


00 


CO 


^ 


GO 


o 


t^ 


00 CO 




t~:i 


5ii 


(N 


co 


T-H 




T-l 


(M 


CO 


1-H 


(N 1-H 




^ 


lO 


00 


q 


CO 


(M 


CO 


^ 


y-< 


Oi o 




s 


00 


t^ 


•*' 


CO 


GO 


00 


00 


d 


d t>^ 




••SI 


CO 


lO 


I— 1 


1— I 


r-H 


CO 


1-H 


1-H 


CO CO 




J3 


E~i 






















i;^ 




























05 


»o 


1— 1 


Oi 


(M 


05 


CO 


00 


CO CO 






^ 


CO 


Th 


co' 


1> 


»o 


d 


d 


CO 


rj5 d 

1-H 




&, 


:^' 










1 




1 




I 






to 

1 


00 


00 


q 


t- 


1-H 


1> 


o 


rH 


(N 00 






^■^ 


ni 


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d 


d 


(M' 


d 


t^ 


1-5 (N 






B-l 




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<N 


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1-H 


(N 


Th 


■<*l 


r-H CO 






t^ 


CO 


(M_ 


tH 


00 


CO 


o 


o 


Oi 


lO (N 






c^' 


Tl^ 


CO 


d 


1-H 


d 


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Tl^ 


d »o 




Bq 






1 














1 






g 


Oi 


q 


o 


o 


CI 


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K 


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t-I 


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IM 


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1-H 




(M 


CO 


CO 


CO CO 








<N 


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(N 


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CO 


CO 


o 


(N 1> 






t^ 


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I— ( 


CO 


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CO 

1-H 


d 

1-H 


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lO 


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00 


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1—1 


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1 


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1 


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CO 


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CO 


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CO 


o 


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o 


1-H 


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00 


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)^ 




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1 












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s 


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00 


00 


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00 


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00 


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Oi T-l 






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oi 


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00 


CO 


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d 


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^ 








1-H 


1-H 


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1 


1 1 




^ 




1-H 


q 


o 


(N 


t- 


I-H 


I> 


1-H 


CO q 






w 


00 


lO 


oi 


d 


Tii 


lO 


1-H 


rJH 


00 CO 






S 


Th 


'^ 


(M 


T-H 


1-H 


t^ 


1-H 




CO 






i'* 




1— 1 














1 






&H 


















1 






8 
























Cl 
























•Si 

•5» 


Pi 
O 


13 


T3 

a 
a 
o 


o 


o 


eg 


si 

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0) o 
O o 



•§ .bO 






TABLES OF RESULTS 



101 






00 rJH T^ CO 
Iff CO <N CO 

i-H CO l-H T-H 



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102 



EFFECT OF DISTRACTION ON REACTION-TIME 



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104 EFFECT OF DISTRACTION ON REACTION-TIME 



TABLE LVII 

Pkeliminaby Test 

Stim. Light, Slim. Light, Stim. Light, 

Svhj. Stimulus Light Dist. Light Dist. Sound Dist. Touch 

A 261.4<r 343.3<r 241.9(r 238.0(7 

6.1 34 6.1 10.1 
B 212.8 260.3 208.9 225.9 

1.9 3.5 1.3 3.0 

After Training in Reacting to Light with Light Distraction 

A 209.8 195.0 218.0 

1.5 2.8 1.7 
B 195.0 199.4 196.5 

1.7 1.6 2.6 

After Training in Reacting to Light with Sound Distraction 

A 217.2 218.8 224.7 

3.2 1.9 1.6 
B 200.9 201.6 222.6 

1.9 1.7 1.6 

After Training in Reacting to Light with Touch Distraction 

A 213.3 207.7 212.9 221.8 

1.9 2.1 3.6 3.3 

B 207.3 217.4 211.5 219.9 

5.6 3.0 2.6 6.4 



TABLES OF RESULTS 105 



TABLE LVIII 
Preliminary Test. 

Slim. Light Stim. Light, Slim. Light, 

Subj. Stimulus Light Dist, Light Dist. Sound Dist. Touch 

C 139.0<r 206.0<r 186.6(7 U9Aa 

1.9 4.7 4-3 10.2 

D 179.6 166.7 154.2 141.8 

4.1 4-5 2.4 2.1 

After Training in Reacting to Sound with Sound as a Dist. 

C 130.9 131.8 148.2 151.2 

1.7 2.2 2.5 2.2 

D 117.3 149.3 162.5 157.2 

1.0 4.1 2.3 6.6 

After Training in Reacting to Sound with Light as a Dist. 

C 119.6 130.9 121.8 

0.8 1.2 1.6 

After Training in Reacting to Sound with Touch as a Dist. 

C 115.2 118.8 124.7 125.0 

1.4 2.1 2.2 2.1 



106 EFFECT OF DISTRACTION ON REACTION-TIME 



TABLE LIX 

Preliminary Test 

Stim. Sound, Stim. Sound, Slim. Sound, 

Subj. Stimulus Sound Dist. Sound Dist. Light Dist. Touch 

E 141.50- 153.20- 143.10- 149.6(r 

2.5 2.4 1.3 3.8 

F 140.0 156.6 167.1 166.4 

1.1 4.0 1.9 11.8 

After Training in Reacting in Sound 

E 139.0 153.7 150.1 145.2 

3.3 2.6 1.9 2.8 

F 121.2 147.4 

0.6 3.6 

After Training in Rracting to Sound with Sound as a Dist. 

E 118.6 126.3 119.5 126.3 

1.3 2.5 1.9 1.6 
F 117.5 120.4 122.5 120.5 

2.4 0.8 2.1 1.2 

After Training in Reacting to Sound with Light as a Dist. 

E 111.1 113.9 111.0 

1.5 0.8 1.3 
F 104.3 101.6 108.1 

2.2 0.9 0.8 

After Training in Reacting to Sound with Touch as a Dist. 

E 111.4 124.2 105.7 111.3 

1.1 2.8 6.3 1.S 

F 123.9 133.9 121.1 135.0 

3.1 1.5 2.0 1.5 



BF21.A7no37 



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PSYCH 

BF21 
A7 
no. 37 



Evans, John Ellis, 1882- 
The effect of dlstractlor 

time, with special refere 

practice and the transfe 

by John £• Evans* New '"' 

Press [ 1916 ] 

2 p. X., 106 p« inr 

25 cm. (Archives of 

R. S. Woodworth. 



40902