'1
\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
27
-' o
+- -
— (^
^-1
If) a
^
a:
I-
o
CO
^
T3
o
CO
6
28
EFFECT OF DISTRACTION ON REACTION-TIME
Pi
EFFECT OF DISTRACTION ON REACTION-TIME
29
X
>
o
30
EFFECT OF DISTRACTION ON REACTION-TIME
■^
I I I I
o
to
X
o
H
fe
EFFECT OF DISTRACTION ON REACTION TIME
31
>
I— I
h- r
X
CO
3
Eh
o
32
EFFECT OF DISTRACTION ON REACTION-TIME
•^
\
-t7-C
O o
Z "
;: f
lo
o
lo
Jo
3-
o
3-
o
lo
o
r#
lo
o
■h
lo JJ
t->
ea
in
^
>e*
/
<
>«-»
1?"
o o
V
51
-j^
^'
•*
(
^
i
\
>
p z:
o ,■
•> « —
li_
r^
y
>
^
£ "« 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
r
^
1
1
'A
X^^777.
T — I — \ — I — I — r
C3 rt rH
i
m.
8
TO t-1
rr
m
wm^
a
W///////M.
T — I — r
T — T
03 t-1
i
qonox
ItlSn
^ -punos
-onojc
•puno3 q::^
•
- 8U0N
• ;uSti
•iBTa
•niT^s
J
r>^^/////M
1 — I — r
■qonol
_ 3U0IC
•Uonoj,
■v&n
■pun 03
• on OH
-■qocoi
-punos
•wan
-eaos
TRANSFER OF TRAINING
57
1 — I — r~T — r
8' Q O O O
I O' €0 CO ^
<0 <q <Q r-l •->
qonoi
■
8U0H
•qonoi
Hon 01
■
IviSiz
-
pun OS
-
©uoH
punos
ttonox
•
punos
.
•m^xi
■
auoH
•^qsn
••3STCI
•KTIS
T — I — I — r
<o CO to
1 — r
"^^^^m
1 — r
ca 00
»-• - lO (0 O rt fH
J
-m
w/////y///////////A
m
1 I I I r
O Q O O O
«<«« — -•
-qonoi
"punog
- 8U0N
punos 01
qonoi
"punos
-man
— euoN
•ninS
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
<o
^
d
d
(M'
d
t^
1-5 (N
B-l
T— 1
<N
<M
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
>o
Tl^
d »o
Bq
1
1
g
Oi
q
o
o
CI
o
Tt<
CO
tH I>
K
^
^
l>
00
c^
OJ
t-I
go'
i> d
IM
ir-l
1-H
(M
CO
CO
CO CO
<N
t-.
o
(N
(N
CO
CO
o
(N 1>
t^
CO
I— (
CO
ci
CO
1-H
d
1-H
d
d
1-H
d d
Q
^'
1
1
1
<»
t^
to
lO
lO
CO
o
CO
"*,
q q
(m'
C<j
TjH
OJ
c^'
d
00
lO
c^i t^
*-?*
00
00
1—1
I— 1
CO
I-H
1-H
CO 1-H
eo
E^
1
1
1
"S
<a
1
t-"
l>
q
CO
00
Id
05
00
i>
(N I>
^'
i6
»o
lO
CO
•*
CO
o
rH
j>; d
o
1-H
IM
1-H
1-H
1-H
(M (M
1—1
05
»— 1
00
00
00
c<!
q
■*
00 ■*
^
t-^
00
»o
d
CO
1^
1-H
■*■
d I-H*
•S
o
Ti<
'^
(N
00
CO
(N
1> 00
)^
^
1
X
^
t^
o
(N CO
(M
Oi
1>
t^
1-H lO
t^
1—1
lO
ci
Tt^ d
m'
d
00
oi
d 00
<
;^
7
1
1 1
1
1 1
H
cq
^
»o
CO
CO
05 O
1>
t^
o
CO
(N J>
s
>o
C<j
c4
(m' d
oi
d
00
00
lO lO
•§
'^
CO
(M
&s
1
1
1
00
r)<
00
rtH
00
■*
lO
CO
Oi T-l
J^
T|H
oi
co'
00
CO
00
1-H
d
CO t>^
^
1-H
1-H
(N
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
.£? o
0) o
O o
•§ .bO
TABLES OF RESULTS
101
00 rJH T^ CO
Iff CO <N CO
i-H CO l-H T-H
00 ■>* lO i-H
ci Tt^ 00 oi
N 1> i-H »Cl
lO O CD CO
05 CO (N CO
CO O 00 (N
O 1>
■^ o
CO CO
00 -"a^
O r-t m CO
•^ CO' (N 05
T-l 05 IM t>.
yj CJl>>-HO CO'OOJ> »Oo6
N
1-; lO lO 00
00 o -^ ci
O Ttl 1-H -"^l
?&^
(N P CO CO
i6 CO O <N
•5 s >-;•>: p ■^
f^ -S CO (M' CO' y-i
3 e^ 1-1 (N TjH CO
l> l-H t^ t>.
C5 (N tH --H
■^ 00 CO rH N; CO
"3 i-i CO CO (M* O
CO
a
00 05 o >c
CO CO p p
O OJ 05 00
t^ioosoo pooio»o
t^ O CO oi (M' TjH (N O
<N CO I— I (N rH
I I
l> 1> 00 t>;
lO 05 i-i CD
(N p
p CO tH CO
(N CO .-H rJH
CO O
ci lo CO CO
y—i
■^ »o CO i-i
>— 1
CO <N
CO t^
(M l> 00 t>. P "3
CO (M' l> i-I CO c^
KJ
i-H 00 p p
Tr ^H ^^ ^H
■-j P ■* CO
O oi 1>^ 00
CO (N lO CO
•§
(N
CO
CO
o
CO
co'
d
CD
s
>— 1
i-H
1
Cl
1
s
CO
05
CO
Tt<
s
(N
CD
00
»o
^
e
CD
T-H
1
1-H
1
Q
1
1
tsi
^
rH^COCO l>pl>.i-|
ioioc<io5 ddcocD
CO (M (N I-I (N CO
I I I I I
C<J I-H GO CO
05 00 C4 CO
tH CD CD l>
■^05 05
tH CO 1-H CO
00 t>; lO •<*_
d CO 05 lo
(N 1-H 00 p
CO CO (n" CO
I I I i
^'^
d t>I
CO T-l
p <M
CO CO
CO 00
co' d
O g M g „ o
a 3
-d ^
"^
!~"
!>
OS
00
t>;
§
^
CO
CO
1-H
lO
1-H
1-H
Q
s
•5
<a
00
IM.
p
■rt*
t
I'S-
CO
tv^
1-H
■*■
ti
(M
00
CO
(N
CQ h^l
^ M
102
EFFECT OF DISTRACTION ON REACTION-TIME
S ■§ t^ «0 '-1 <3?
•S
00 CO (N 1-J
ti
s
CD •*' CO 1-H
(M CO 1-1 i-l
CO fo «q (N
1> ^^ CC CO
q (N '*.
t--^ CO CD
X
lO
"^
i>
a>
d
»o
T— 1
•*
^ -S
^ i
o
■*
lO
CO
Cig
1
T)H
00
1
03
1
± s
1
1
1
•^ -5
•S
"t ^*
(N
T|H
CD
o
fe^
OJ
I>
1—1
d
T— 1
Q
s
1— 1
•o
lO
00
^1
00
d
rl^
(N
rH
1
i-i
1
1—1
tt5
^^
fe^
■* i> q CO
1-5 id c<i cd
»0 Cft CD o
IC C<j (N CO
oq
(N 05 t>; l>
(N d 00 05
!> 1-j q CO
C5 1-5 CO 00
I I I
'^ ;=;
t^ i-( t>;
00 CO O »c
X
(—1
X
w
H
Q
00 ■* (N rji
Tji OJ CO 00
•^ i» I— I CD O (M
fe
cT Til -TP
•>* r)^ lO q
(n" ci 1-5 (N
t^ 1-;
i-< Tj5
S^
fee
^3
1^
?&;
05 q -^^ q
(N id CO CO
^ I
!> lo q 00
i>^ d CO oJ
(M CD rH
I I
Q
i> i> q i>.
id d 1-5 CO
i-j 1-; rt< CO
id id (N d
CO (M IM
I I I I
J - o o
125 k5 c» H
CQ hA
^ CB H^ H
-73
o
w.
^
(N r-J CO CO
d 00 c<l CO
I I
I-I CD q !>;
■DH d d d
I I I
.. ^ 'T5 A
•2 § M g o
TABLES OF RESULTS
103
<q CO th (N
T-H O lO i-H
05 CO rhi CO
CO CO OJ ci
(N 00 (N TJH
CO O O 1>
C? Tt< 1— I rt*
TJ^ Oi CO 1-H
»0 1-H CO CO
(N CO p O
O oi 03 00
(N
CO
1— 1
^.
Tin
lO
co'
T— 1
T— (
1
(— 1
1— 1
1— 1
k5
O
IM
lO
iCl
(N
lO
CO
d
H
1
T-H
1
(N
t^
00
1>;
CO
c<i
J>I
1—1
fiq
o>
q
r^
lO
ici
CO
oi
rti
CO
■*'
CO
oi
CO
(M
CO
CO
i-l
s
05
T-(
CO
t^
CO
1>
CO
I— (
1
s
CO
00
Oi
I>
Is
•>*
CO
I— 1
a'
CO
1
1
CO
00
d
?fe5,
^fej >
Oi o o o
(N 1> Oi (N
CO lO co' (N
1> CO "5 lO
(m' ci •*' oi
00 00 i-H i-H
I
CS5
^
t^ CO 1> T-(
00
t^
»o rjj
d
1—1
1
CO
1
d lo
(M
1— (
00 05
CO
1
CO
CO
1
(N CO
I— 1
i
a
3
O
02
Ml 5
73
O
S^" 1> O CO 00
'^ ■ ■ " ■
05 i-H |> 00
i> 00 »o d
CO ■* lO
I I
•2 o M g §
OQ h^
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
3 9358 00040902 6
This book may be kept hri.Ll.W.. weeks.
A fine of two cents will be charged for each day
books or magazines are kept overtime.
Two books may be borrowed from the Library at
one time.
Any book injured or lost shall be paid for by the
person to whom it is charged.
No member shall transfer his right to use the
Library to any other person.
^
fTj Accession numbe
Dafe Due.
FEB 1 3 mZ
■/
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
Live Music Archive
Librivox Free Audio
Metropolitan Museum
Cleveland Museum of Art
Internet Arcade
Console Living Room
Books to Borrow
Open Library
TV News
Understanding 9/11