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

subject also showed no preference for objects. With the subjects S

and B the preference for actual movements is not marked, and has

importance only in the light of later experiments to be reported.

The great difference in the retentive power of different subjects is,

as we should expect, very evident. Roughly, they may be divided into

two groups. M and Mo recall much more than the other four. The

small percentage of recall in the case of these four suggested the

next change in the conditions of experimentation, namely, to shorten

with them the intervals between the tests for permanence. This was

accordingly done in the C set. But before giving an account of the

next set we may supplement these results by results obtained from

other subjects.

It was impossible to repeat this set with the same subjects, and

inconvenient, on account of the scarcity of suitable words, to devise

another set just like it. Accordingly, the B set was repeated with

six new subjects. We may interpolate the results here, and then resume

our experiments with the other subjects. The conditions remained the

same as for the other subjects in all respects except the following.

The tests after nine and sixteen days were omitted, and the remaining

test for deferred recall was given after one day instead of after two.

In learning the series, each series was shown four times instead of

three. The results are summarized in the following table. The figures

in the left half show the number of words out of sixteen which were

correctly recalled. The figures in parentheses separate, as before,

the correctly recalled indirect-association couplets. In the right

half of the table the same results, omitting indirect-association

couplets, are given in per cents, to facilitate comparison with the

summary from Tables I. and II.

TABLE III.

SHOWING RECALL AFTER ONE DAY.

N. O. V. M. N. O. V. M.

Bur. 6 10(1) 7(1) 5(4) 38 67 44 31

W. 5(3) 12(1) 6 9 31 75 38 56

Du. 1 11(1) 8 9 6 69 50 56

H. 9(1) 14 8 12 56 88 50 75

Da. 1(3) 7(4) 3(1) 9(3) 7 44 20 56

R. 7(2) 3(3) 5 5(1) 44 19 31 31

Total, 29(9) 57(10) 37(2) 49(8) Av., 30 60 39 51

Av. gain in object couplets, 30 per cent.

” ” ” movement couplets, 12 per cent.

The table shows that five subjects recall objects better than images

of objects, while one subject recalls images of objects better.

Similarly, three subjects recall actual movements of the body better

than images of the same, while with three neither type has any

advantage.

THE C SET.

In the C set certain conditions were different from the conditions

of the A and B sets. These changes will be described under three

heads: changes in the material; changes in the time conditions; and

changes in the method of presentation.

For lack of monosyllabic English words the verbs and movements were

dissyllabic words. The nouns and objects were monosyllabic, as before.

All were still concrete, and the movements, whether made or imaged,

were still simple. But the movements employed objects, instead of

being merely movements of the body.

For two of the subjects, M and Mo, the time intervals between the

tests remained as in the A and the B sets, namely, two days, nine

days, and sixteen days. With the four other subjects, S, Hu, B, and

Ho, the number of tests was reduced to three and the intervals were

as follows:

The I. test, which as before was a part of the learning process, was

not counted. The II. test followed from 4½ to 6½ hours, or an average

of 5-3/8 hours, after the I. test. The III. test was approximately 16

hours after the II. test for all four subjects.

The series were learned between 10 a.m. and 1:30 p.m., the II. test

was the same day between 4:30 and 5:10 p.m., and the III. test was the

following morning between 8:30 and 9:10 a.m. Each subject of course

came at the same hour each week.

Each series was shown three times, as in the B set.

A change had to be made in the length of exposure of each couplet in

the movement series. For, as a rule, movements employing objects

required a longer time to execute than mere movements of the body.

Five seconds was found to be a suitable length of exposure. To keep

the three other types of series comparable with the movement series,

if possible, their exposure was also increased from 3 to 5 secs. The

interval of 2 secs, at the end of a presentation was omitted, and the

interval between learning and testing reduced from 4 secs, in the B

set to 2 secs.

In the movement series of the A and B sets, movements of parts of

the body were chosen. But the number of such movements which a person

can conveniently make while reading words shown through an aperture is

limited, and as stated above no single word was ever used in two

couplets. These were now exhausted. In the C set, therefore,

movements employing objects were substituted. The objects lay on the

table in a row in front of the subject, occupying a space about 50 cm.

from left to right, and were covered by a black cambric cloth. They

were thus all exposed at the same moment by the subject who, at a

signal, laid back the cloth immediately before the series began, and

in the same manner covered them at the end of the third presentation.

Thus the objects were or might be all in view at once, and as a result

the subject usually formed a single mental image of the four objects.

With this kind of material it was no longer necessary for the operator

to show the subject in advance of the series what the movements were

in order to avoid hesitation and confusion, for the objects were of

such a nature as obviously to suggest in connection with the words the

proper movements.

TABLE IV.

SHOWING RECALL AFTER TWO, NINE AND SIXTEEN DAYS FOR TWO SUBJECTS, AND

AFTER FIVE HOURS AND TWENTY-ONE HOURS FOR FOUR OTHER SUBJECTS.

Days. Two. Nine. Sixteen Two. Nine. Sixteen

N. O. N. O. N. O. V. M. V. M. V. M.

Series M.

C^{1-4} 4 4 4 4 3 2 3 2 2 2 1 1

C^{5-8} 2 2 2 2 2 1 1 1 1 2 1 0

C^{9-12} 3 2 3 1 3 0 2 4 3 2 2 1

C^{13-16} 4 3(1) 4 2(1) 4 2(1) 3 4 2 3 2 3

Total 13 1(1) 13 9(1) 12 5(1) 9 11 8 9 6 5

Per cent. 81 73 81 60 75 33 56 69 50 56 38 31

Mo

C^{1-4} 2 4 1 1 1 1 1 4 1 2 1 2

C^{5-8} 3 2 4 1 3 1 4 3(1) 4 3(1) 2 2(1)

C^{9-12} 0 1 0 1 0 1 0 3 0 1 0 2

C^{13-16} 0 0(1) 0 0(1) 0 0(1) 1(1) 4 1(1) 2 0(1) 0

Total 5 7(1) 5 3(1) 4 3(1) 6(1) 14(1) 6(1) 8(1) 3(1) 6(1)

Per cent. 31 46 31 20 25 20 40 93 40 53 20 40

Hours. Five. Twenty-one. Five. Twenty-one

N. O. N. O. V. M. V. M.

Series S.

C^{1-4} 1 3 1 1 0 1 0 1

C^{5-8} 0(1) 3 0 2 0 1 0 1

C^{9-12} 0(1) 3 0(1) 4 3 4 3 4

C^{13-16} 1 3 1 3 2 3(1) 3 3(1)

Total 2(2) 12 2(1) 10 5 9(1) 6 9(1)

Per cent. 14 75 14 63 33 60 40 60

Hn.

C^{1-4} 1 4 1 4 0 4 1 4

C^{5-8} 0(2) 1 0(2) 1 0(1) 2 1(1) 2(2)

C^{9-12} 3 4 3 4 2 4 2 4

C^{13-16} 1 3 3 3 0 3(1) 0 2(1)

Total 5(2) 12 7(2) 12 2(1) 13(3) 4(1) 12(3)

Per cent. 36 75 50 75 14 100 29 92

B.

C^{1-4} 3 4 3 4 3 4 3 4

C^{5-8} 3 2 3 3 2 2 2 4

C^{9-12} 2 4 2 3 2 1 2 2

C^{13-16} 3 4 3 4 2 4 2 4

Total 11 14 11 14 9 11 9 14

Per cent. 69 88 69 88 56 69 56 88

Ho.

C^{1-4} 3(1) 2(2) 3(1) 2(2) 0 3(1) 0 1(1)

C^{5-8} 3(1) 4 3(1) 4 3 3(1) 3 3(1)

C^{9-12} 1(2) 4 1(2) 4 2(1) 3(1) 2(1) 3(1)

C^{13-16} 0 2 0 2 2 4 2 4

Total 7(4) 12(2) 7(4) 12(2) 7(1) 13(3) 7(1) 11(3)

Per cent. 58 92 58 92 50 100 50 85

The object series were also changed to conform to the movement series.

Formerly the objects had been shown successively through the aperture

and synchronously with their corresponding words; now they were on the

table in front of the subject and all uncovered and covered at once as

in the movement series. The subjects therefore had a single mental

image of these four objects also.

In both the object and the movement series the objects as before were

small and fairly uniform in size and so selected as not to betray to

the subject their presence beneath the cloth in the I. test. In the

II., III. and IV. tests there were no objects on the table.

The previous table shows the results of the C set. The figures give

the number of couplets correct out of four; the figures in brackets

give the number of indirect associations; the total number recalled in

any series is their sum.

In the following summary the recall of M and Mo after two days and

of S, Hu, B and Ho after twenty-one hours are combined.

SUMMARY FROM TABLE IV.

N. O. V. M.

M. 81 per cent. 73 per cent. 56 per cent. 69 per cent.

Mo. 31 ” 46 ” 40 ” 93 “

S. 14 ” 63 ” 40 ” 60 “

Hu. 50 ” 75 ” 29 ” 92 “

B. 69 ” 88 ” 56 ” 88 “

Ho. 58 ” 92 ” 50 ” 85 “

–––— –––— –––— –––—

Av. 51 per cent. 73 per cent. 45 per cent. 81 per cent.

Av. gain in object couplets, 22 per cent.

” ” ” movement couplets, 36 per cent.

Before asking whether the results of the C set confirm the

conclusions already reached, we must compare the conditions of the

three sets to see whether the changes in the conditions in the C set

have rendered it incomparable with the other two. The first change was

the substitution of dissyllabic words in the verb and the movement

series in the place of monosyllabic words. Since the change was made

in both the verb and the movement series their comparability with each

other is not interfered with, and this is the point at issue.

Preliminary tests, however, made it highly probable that simple

concrete dissyllabic words are not more difficult than monosyllabic in

5 secs. exposure. This change is therefore disregarded.

The first important change introduced in the C set was the reduction

of the intervals between the tests for four subjects. The second was

the lengthening of the exposure from 3 to 5 secs. These changes also

do not lessen the comparability of the noun, object, verb and movement

series with one another,