Sixteen Experimental Investigations from the Harvard Psychological Laboratory by Hugo Münsterberg (100 books to read .txt) 📕

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