Various - Harvard Psychological Studies, Volume 1

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The change from red to yellow caused 'an unpleasant sensation' in C.
and the new figure 'had a maroon halo.'

A. in returning from green or blue to yellow passed through a gray;
so, once, in changing from yellow to green, and once, green to red.
With A. blue retinal clouds, which often came, aided changes to blue
and hindered at times changes to other colors. B. had a fusion of
yellow and red in changing from yellow to red. G. had a tendency to
leave uncolored the lower left-hand corner and it 'was wood-colored';
G. had a gray image as the result of fusion of retinal clouds with red
memory image. With H. blue always came in as robin's-egg blue, which
then had to be changed to the standard blue. In one instant the green
memory image seemed to shift into a purple and change to a positive
retinal image which interfered with changes to other colors. J. found
whistling and humming an aid in relaxing an unnatural state of tension
which would hinder the best results. To increase the vividness of the
image he would recall the black background on which the colored
squares had hung. In one experiment K. became 'desperately tired of
yellow,' which was the presented color, so that his 'mind was ready to
jump to any color rather than yellow.' The returns to yellow were, in
this experiment, slower than the changes from yellow.

The images sometimes changed sizes, being at times smaller, but
usually larger than the object. In one experiment of C. the image was
four times the size of the object, which was a green square with sides
of one inch.

III. MOVEMENTS OF TWO IMAGES IN THE SAME AND IN DIFFERENT DIRECTIONS.

Table IV. gives the results of experiments in the movements of two
images, the objects presented being colored squares or discs. Time of
perception was five seconds. After the disappearance of after-images,
if there were any, eighteen to twenty-four movements with returns to
original positions were made, occupying five or six minutes. The
colors were saturated blue, green, yellow and red. Four of the
movements were such as separated the two images, and in four the two
moved uniformly. The first four movements were right and left, left
and right, up and down, down and up; the left-hand object followed the
first direction indicated. The right-and-left movements involved the
crossing of the images. The last four were _both_ to right, to left,
up, down. The time was taken with a stop-watch and includes the time
between the director's word of command and the subject's report,
'now.' It includes, therefore, two reaction times. The subject
reported the instant the colors reached, or appeared at, the suggested
positions.

It is to be noticed that H. was very much slower than any of the
others in making the movements, both out and back; and that K., while
also slower (though much less so than H.) in making the movements
outward, was no slower in making the return movements.

TABLE IV.

MOVEMENTS OF TWO IMAGES.

Twenty movements of each kind for each subject. Averages in seconds.

In Opposite Directions.

Subj. L.-R. Ret. R.-L. Ret. U.-D. Ret. D.-U. Ret.

B. 1.82 2.90 2.10 2.27
0.86 0.87 0.73 0.86

G. 3.02 2.86 2.68 2.63
1.98 2.25 1.63 2.01

H. 9.18 10.30 7.50 7.15
5.16 6.90 5.36 5.21

I. 4.17 3.52 3.40 3.37
1.26 1.47 1.23 1.31

J. 2.17 2.90 2.87 2.27
1.05 1.63 1.02 1.13

K. 5.51 6.43 5.16 4.81
1.43 1.48 1.20 1.23

Ave. 4.32 4.82 3.82 3.75
1.96 2.43 1.87 1.96

Average of all movements involving separation (480), 4.18. Returns, 2.06.

In Same Direction.

Subj. R. Ret. L. Ret. U. Ret. D. Ret.

B. 1.31 1.22 1.30 1.11
0.72 0.67 0.72 0.85

G. 2.66 2.35 3.01 2.53
2.00 1.86 2.22 1.86

H. 8.45 7.91 5.66 7.66
6.53 5.95 5.96 6.11

I. 2.57 2.27 2.13 2.05
0.97 1.26 1.00 1.13

J. 1.11 1.16 1.08 11.5
0.68 0.90 0.73 0.71

K. 3.97 3.91 3.60 4.07
1.35 1.50 1.75 1.71

Ave. 3.33 3.14 2.79 3.10
2.04 2.02 2.04 2.06

Average of all movements together (480), 3.09. Returns, 2.04.

NUMERICAL.

There were nineteen hundred and twenty movements in all, including the
returns to the original positions.

In the order of difficulty as shown by the time taken, the movements
stand as follows, the numbers being the averages in seconds for one
hundred and twenty movements of each kind:

1. Right and left (_i.e._, crossing), 4.82 sec.
2. Left and right, 4.32 "
3. Up and down, 3.82 "
4. Down and up, 3.75 "
5. Both right, 3.33 "
6. Both left, 3.14 "
7. Both down, 3.10 "
8. Both up, 3.04 "

SUBJECTIVE.

In the experiments in which the time was recorded, there was no
disappearance of either image except where movements were made
successively. In these cases frequently the image which was awaiting
its turn vanished until the first image was placed, a time varying
from a quarter of a second to three or four seconds. Occasionally the
image already placed would vanish, while the other was _en route_; the
subject's attention in both these cases being centered exclusively on
the image he desired to move. This was especially the case when the
distances to which the images were moved were great, as to the ends of
the room or to ceiling and floor. In other experiments, where, after
the movements took place, the images were held for a short time, there
were disappearances of one image or the other ranging from one quarter
of a second to fifteen seconds, most of the absences, however, being
under five seconds. The absences were more numerous in the latter half
of the five minutes covered by the experiment. Occasionally a noise in
the adjoining room or in the street made the images disappear.

The greater ease of vertical as compared with horizontal movements
recalls an observation of Ladd,[3] in which the idioretinal light was
willed into the shape of a cross. Ladd says: "The vertical bar of the
cross seems much easier to produce and to hold steadily in the field."
This present observation is also in accord with that described above
in the case of movements of a single image.

[3] Ladd, G.T.: 'Direct Control of the Retinal Field,' PSYCH.
REV., 1894, L, pp. 351-355.

On several occasions G. reported that the crossing movement was the
easiest, and that the return to the original places was not easier
than the other movements. In one experiment he reported the field at
the center cloudy, so that it was a relief to get away from it. G.'s
time records on these occasions did not support his feeling with
regard to the return to the original places, but they show that the
crossing movements were, in two or three instances, quicker than the
'left-and-right' movement, and the impression of promptness thus made
persisted to the end of the experiment. The four movements in which
both images moved uniformly were easier than the four in which
movements in different directions were involved.

All the subjects were frequently conscious of eye movements, and more
frequently conscious of a tendency to eye movement, which was,
however, inhibited. That the strain in the eyes was practically
constant during all the movements away from the original places, seems
evident from the unanimous reports of a sense of relaxing and relief
in the eyes, attending the movement of returning to the original
places. The distance to which the images were moved was a powerful
factor in producing this sense of strain. When the two images were
moved and held but a few inches apart there was no sense of strain and
no conscious alternation of attention. Practice increased greatly the
distance at which the images could be held apart without conscious
alternation of attention, but the strain of holding them apart and of
inhibiting eye movement increased with the distance.

In the movements for which the time was recorded the distances varied,
according to the subject, from six to eighteen inches, and varied at
times with each subject. In the experiments without time record, A.,
B., C., E., F. and H. reported that they were able to move the images
apart to ceiling and to floor, or to the opposite ends of the room,
and to hold them there both in consciousness at the same time without
either alternation of attention or eye movement, a tendency to which
was felt but was inhibited. I. held them two feet apart without
fluctuation of attention. A. reported: "I tend to turn my body to left
or to right when I move the images in either of these directions." C.,
H. and I. said: "The eyes diverge when one image moves slowly to the
right and one to the left." D. found a slight movement of the eyes
which could be detected by the fingers placed lightly on the lids,
when the attention was alternating between the images. K. had
convergence and divergence of the eyes for crossing and separation
respectively and he was accustomed to run his eye over the outline of
the image. Strain in the scalp muscles was reported by A., B., E., F.
and G. The up-and-down movements were universally characterized by a
feeling as if one eye tended to move up and the other down. C.
unconsciously inclined his head to the left in such movements as if to
make the line of the two eyes parallel with the direction of the
movement.

E., when holding the images two feet apart, had a strong feeling of
difference of accommodation when alternating in observation and so
judged the two to be in different planes.

When the movement seemed difficult the strain was greater, and when an
image became dim the effort to restore its brightness or its
distinctness of outline was accompanied by a feeling of bringing it
nearer by accommodation and near focusing. J. found that the two
images approached each other when he attempted to secure greater
vividness. An analogous instance is that of A.G.C., a subject quoted
in 'Mental Imagery of Students,' by French.[4] In calling up the image
of a die this subject held up his hand as if it held the die. When
there was no sense of strain the hand was fourteen inches from his
face, but when effort was made to image all the sides of the die at
once he unconsciously moved his hand to within four inches of his
eyes. French says in this connection: "Situation depends on the
attention involved and the inference is near that this phenomenon may
be connected with feelings of convergence and accommodation which so
often accompany concentrated visual attention."

[4] French, F.C.: PSYCH. REVIEW, 1902, IX., p. 40.

The movements were assisted by mentally saying, 'this image is here,
that image is there,' in the case of D., G., H., I. and K.; or, at
times, by articulating the names of the image, or of the color when
the image was of a colored object. I. found it easy to hold outlines,
but in order to retain colors in the movements of separation, he had
to speak the names continually. H. also repeated the names
continually, as, for example, 'violet here, orange there.'

A. represented the line of vision as going to each of the two images,
which seemed connected by a line, thus making a triangle, and then
pictured himself as standing off and seeing himself looking at the
images. When the two objects were solid and the images were to be
crossed, B. carried one image above or below the other, but when the
objects were colored surfaces he conceived them as pure colors so that
there was no sense of impenetrability to interfere with their crossing
and they glided by each other. In the up-and-down movements he moved
one at a time. C. and D. had to construct some support for the images.
In most of the experiments H. first moved the images to a greater
distance away, somewhat higher up and a little farther apart. In this
new position the images appeared smaller and the suggested movements
were made more easily. Sometimes in crossing two colored images he
observed a partial mixture of the colors. J. found that a sharp
movement of the head in the required direction aided materially in
moving the images, and when the objects were colored surfaces fastened
to the same card he found it necessary either to conceive the card as
of rubber or to picture it as cut in two before he could make the
movements of the images.

With A., B., C. and D. there were instances of unwilled movements of
the images, in the experiments where the movements were not timed.
These were much more frequent with D. than with the others, and to
check them required prolonged effort. The more common movements of
this sort were rotation of the image, change of its position,
separation of its parts (if detachable in the object) and change of
shape. E. had a return of the two images of a preceding experiment
which persisted in staying a few seconds and which were as vivid as
the two legitimate occupants of the mental field.

The images were duplicated five times on different days with A., and
once each with C., F. and K.

A.'s cases were these. The 'wraith' of a small box whose image was out
at the right, appeared above the other image off at the left and it
was turned with a corner to the front. Again, at the central position
each image was duplicated, the true pair being of full size, bright
and distinct, the false pair small, dim and on a more distant plane,
_i.e._, behind the others. One of the extra images persisted against
all effort to banish it, for fifty-five seconds. Again, when twelve
inches apart each image was similarly duplicated. In the fourth
instance the images were at the center of the field. In the fifth, the
right image, eight inches from the center, was duplicated, the extra
image being still farther away and above. This second image was very
dark, dim and vague in outline, and came and went slowly. The right
image of C., when seven feet from the center, had a dim double above
it. F. had moved the right-hand image (a violet disc) close to the
left when a blue disc also appeared above it. Though repeating the
word 'violet' he had imaged the violet disc as blue. K. was holding
the two images a foot and a half apart when an extra pair appeared at
the center. Both pairs persisted for sixty seconds and then the outer
pair vanished, and the inner, the false pair, grew brighter.

As was said in the case of a single image, so with double images, the
motion could be traced and often was traced when the movements were
away from the original positions, but on the return to the original
positions the images were not usually seen _in transitu_. For ten of
the subjects, the image moved downward uniformly on an arc whose
center was at the eye; and often the right and left movements were
likewise on an arc. With E. the ends of the arc for motion right and
left were higher also. H., I. and J. reported that all the movements
were in the same plane. The upward movement was always to a less
distance and the downward movement to a greater distance than the
horizontal movements.

In most cases the images were the size of the percepts, in a number of
cases smaller, and in a few cases larger. This was determined by
comparison between the image and the percept immediately on opening
the eyes and seeing the object at the end of the five minutes occupied
by the experiment. A similar mode of comparison showed that, in about
half of the experiments, the images were at the end of five minutes
approximately equal to the percept in clearness and distinctness of
outline. A comparison of these results with those obtained in a series
of experiments involving passive observation of the image seems to
indicate that active manipulation of the image tends to maintain the
qualitative fidelity of the image when at its original position.
During the progress of the experiments the reports were almost
unanimous and constant that at its original position the image was
vivid and distinct, but lost in both respects when away from that
position, the loss being greater the greater the distance to which it
was moved. Frequently there was fluctuation,--a loss of vividness and
then a restoration,--which A. frequently found to be rhythmical, while
in general it was evident that an increase of effort or of attention
was successful in restoring lost vividness and distinctness.

D., after three minutes, read the time in the image of a watch. In
superposing green on yellow, in two instances, the yellow shone
through, making a mixed color, and again, in moving a green disc and a
yellow disc, the green became suffused with yellow, so that the two
discs were one yellow and the other greenish-yellow. For C.,
similarity in the two objects presented tended to make both images
less vivid and distinct and to render more difficult their retention
and manipulation. When one of the two objects partially overlapped the
other it was difficult to separate the two images, and the area of
contact was very vague in the image of the under one, and when the
scrutiny reached that portion the other image returned to its original
overlapping position.

IV. SUPPRESSION OF ONE OF TWO IMAGES.

The next tables (V. and VI.) give the results of experiments in
suppressing one of two images, the objects presented being saturated
color squares, discs, triangles, etc., placed side by side, one above
the other, or a smaller one superposed on a larger. The time of
perception was five seconds. After the disappearance of after-images,
if there were any, the subject was directed to suppress one of the two
memory images, the one to be suppressed being indicated by the
director. The subject reported as soon as the indicated image
disappeared, and reported any return of the suppressed image and its
later disappearance in consequence of his efforts. Also he reported
any disappearance and reappearance of the retained image. Five minutes
was the limit of the time for the experiments with a few exceptions.
The times were recorded, and those given for the first suppression
include the time between the director's command and the subject's
report 'now' or 'gone,' and include, therefore, two reaction times.
The later suppressions include but one reaction time.

TABLE V.

SUMMARY OF ALL SUPPRESSIONS. AVERAGE TIME IN SECONDS.

[Label 1: Image Suppressed]
[Label 2: No of Exper.]
[Label 3: Time of First Supp.]
[Label 4: Time of Ab. of Supp. Im.]
[Label 5: No. of Later Supp.]
[Label 6: Time of Later Supp.]
[Label 7: No. of Ab. of Supp. Im.]
[Label 8: Time of Ab. of Supp. Im.]
[Label 9: Time of All Supp.]
[Label 10: Time of All Absence of Supp. Im.]

[1] [2] [3] [4] [5] [6] [7] [8] [9] [10]
Right. 46 11.59 82.39 221 8.43 216 35.74 8.94 43.93
Left. 43 11.89 79.34 175 7.79 173 44.86 8.60 51.26
Upper. 22 11.67 49.77 150 6.26 147 29.75 6.95 32.35
Lower. 17 14.23 64 71 7.88 70 46.68 9.11 50.04
Central. 42 18.24 96.93 357 3.90 352 18.13 5.41 26.54
Marginal. 20 14.25 181.57 24 8.93 24 78.08 11.35 125.12
Sundry. 7 8.71 127.21 19 13.34 19 47.27 12.09 68.78
Averages. 13.48 91.25 6.46 32.14 7.60 41.86

TABLE VI

SUPPRESSIONS GROUPED BY SUBJECTS. AVERAGE TIME IN SECONDS.

[Label 1: Subject]
[Label 2: No. of Exp.]
[Label 3: Time of First Supp.]
[Label 4: Time of Ab. of Supp. Im.]
[Label 5: No. of Later Supp.]
[Label 6: Time of Later Supp.]
[Label 7: No. of Ab. of Supp. Im.]
[Label 8: Time of Ab. of Supp. Im.]
[Label 9: Time of All Supp.]
[Label 10: Time of All Ab. of Supp. Im.]

[1] [2] [3] [4] [5] [6] [7] [8] [9] [10]
A. 11 28.32 11.29 117 14.90 114 10.35 16.05 10.44
B. 29 5.79 270.44 5 0.25 5 138.80 4.98 251.08
C. 18 7.88 43.08 64 3.94 63 67.49 4.81 62.07
D. 14 23.28 190.07 6 31.66 5 204.60 25.80 193.89
F. 10 12.67 86.07 230 1.95 230 67.92 2.40 10.09
G. 21 21.88 20.39 190 9.97 184 19.37 11.15 19.47
H. 21 15.27 73.27 47 10.30 47 84.48 11.84 81.02
I. 26 9.77 53.83 96 5.06 94 61.34 6.06 59.72
J. 26 3.59 32.18 209 1.40 208 31.69 1.64 31.75
K. 21 21.63 71.90 53 14.75 51 70.04 16.70 31.83
Averages. 13.48 91.25 6.46 32.14 7.60 41.86

There were ten subjects in most of the experiments, and the marked
differences in the individual records which were evident in the
previous experiments did not exist here except in the case of A., for
whom alone the time required to obtain the suppression exceeded the
time of absence of the suppressed image.

In several experiments the subjects were unable to suppress the
indicated image, which in five cases was the image at the center of a
disc and in two cases the outer portion of the disc. Further, five
failures were by one subject, D., and one each by A. and F. The
statistical report here given includes only the results of the
successful experiments. Forty-four of the one hundred and ninety-seven
were completely successful, as the suppressed image did not return
throughout the entire period. The following table shows the grouping
of the experiments according to the recurrence of the suppressed
image:

Returned 0 times, 44
" 1 " 26
" 2 " 18
" 3 " 25
" 4 " 16
" 5 " 16
" 6 to 10 " 28
" more than 10 times, 24
Total, 197

Seventy-three and three fifths per cent. of all the experiments have
five or fewer returns of the suppressed images.

The subjects suppressed the image as soon as possible after each
return, the average time taken to accomplish these later suppressions
being 6.46 sec., while the average time of absence of the suppressed
image was 32.14 sec.

Including the first efforts and the first absences of the suppressed
image, the average time required to suppress the image was 7.60 sec.,
and the average time of absence of the suppressed image was 41.86 sec.

Arranging the subjects according to the average time they required to
accomplish a suppression, we have the following order. J. and F. had
more recurrences of the suppressed image than any of the other
subjects.

J. 1.64 sec.
F. 2.40 "
C. 4.80 "
B. 4.98 "
I. 6.06 "
G. 11.15 "
H. 11.84 "
A. 16.05 "
K. 16.70 "
D. 25.80 "

Arranging them by the average absence of the suppressed image we have
this order:

B. 251.08 sec
D. 193.89 "
H. 81.02 "
C. 62.07 "
I. 59.72 "
K. 31.83 "
J. 31.75 "
G. 19.47 "
A. 10.44 "
F. 10.09 "

It is to be remarked, however, that the ability to keep the suppressed
image out of the field increased with practice and that A. and F. had
less than half the number of experiments that the rest had. D., who
had but two thirds as many as most of the other subjects and therefore
had less practice in suppressing the image, stands yet second in
respect to this ability.

If we compare the subjects with regard to _first_ efforts and _first_
absences only, we obtain the following orders:

According to Ave. Time req. According to Ave. Absence
for first Suppression. of Image after first Suppression.
J. 3.59 sec. B. 270.44 sec.
B. 5.79 " D. 190.07 "
C. 7.88 " F. 86.07 "
I. 9.77 " H. 73.27 "
F. 12.67 " K. 71.90 "
H. 15.27 " I. 53.83 "
K. 21.63 " C. 43.08 "
G. 21.88 " J. 32.18 "
D. 23.28 " G. 20.39 "
A. 28.32 " A. 11.29 "