Harvard Psychological Studies Part 24

_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 a.s.sociations; 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 subst.i.tution 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, since they affected all series of the _C_ set.

The third change in the conditions was the subst.i.tution in the movement series of movements employing objects for movements of the body alone, and the consequent placing of objects on the table in the movement and in the object series of which the subject obtained a single mental image. All of the subjects were of the opinion that this single mental image was an aid in recall. Each of the objects contributing to form it was individualized by its spatial order among the objects on the table. The objects shown through the aperture were connected merely by temporal contiguity. On this account the object and the movement series of the _C_ set are not altogether comparable with those of the _A_ and the _B_ sets. We should expect _a priori_ that the object and the movement series in the _C_ set would be much better recalled than those of the _A_ and the _B_ sets.

The fourth change was from imaged or made movements of the body alone to imaged or made movements employing objects. If, as the _A_ and the _B_ sets have already demonstrated, the presence of objects at all is an aid to recall, the movement series of the _C_ set should show a greater gain over their corresponding verb series than the simple movements of the body in the _A_ and the _B_ sets showed over their corresponding verb series. For, employing objects in movements is adding the aid of objects to whatever aid there is in making the movements.

Turning to the results, we consider the _C_ set by itself with reference to the effect of the use of objects vs. images in general.

The summary from Table IV. shows that under the conditions given, after intervals of from slightly less than one day to two days, five of the six subjects recall object couplets better than noun couplets.

One subject, _M_ recalls noun couplets better. It also shows that under the conditions and after the intervals mentioned all six subjects recall movement couplets better than verb couplets. In view of the small difference here and of his whole record, however, _M_ is probably to be cla.s.sed as indifferent in both substantive and action series.

RECALL AFTER NINE AND SIXTEEN DAYS.

Thus far recall after these longer intervals has not been discussed.

The experiment was originally devised to test recall after two days only, but it was found that with two of the subjects, _M_ and _Mo_, recall for greater intervals could be obtained with slight additional trouble. This was accordingly done in the _B_ and _C_ sets. The results of the four other subjects in the _B_ set are not so satisfactory on this point, because not enough was recalled.

The most interesting fact which developed was an apparently slower rate of forgetting, in many cases, of the nouns and verbs than of the objects and movements. In the noun-object group of the _B_ set it is noticeable in three out of the four possible subjects, viz., _B, Ho_, and _Mo_. _M_ alone does not show it. The two other subjects, _S_ and _B_, did not recall enough for a comparison. In the verb-movement group of the _B_ set it is also marked in three out of the four possible subjects, viz., _M_, _Ho_, and _Mo. B_ alone does not show it. It is also seen in the _C_ set in the results of _M_ and _Mo_, in both the noun-object and the verb-movement groups. With the four other subjects in the _C_ set it could not be noticed, since the series ran their course in a day. In _M_ (verb-movement group, _C_ set) and _Mo_ (noun-object group, _C_ set) the originally higher object or movement curves actually fall below their corresponding noun or verb curves.

The results of the tests for recall after nine and sixteen days are summarized in the following tables. They should be compared with the recall of these same series after two days given in Tables II. and IV., nor should it be forgotten that all four types started with perfect immediate recall. The figures give per cents, correct after eliminating indirect-a.s.sociation couplets.

TABLE V.

SHOWING RECALL AFTER NINE AND SIXTEEN DAYS.--SUMMARY FROM _B_ SET.

Days. Nine. Sixteen Nine. Sixteen.

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

_M._ 36 38 29 31 56 19 50 31 _S._ 0 6 0 6 0 7 0 0 _Hu._ 0 7 0 20 0 25 0 6 _B._ 13 21 13 13 7 20 7 13 _Ho._ 25 23 17 0 25 33 0 8 _Mo._ 57 63 57 56 20 79 20 69 Av. 22 26 19 21 18 31 13 21

TABLE VI.

SAME FOR _M_ AND _Mo_.--SUMMARY FROM _C_ SET.

Days. Nine. Sixteen. Nine. Sixteen.

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

_M_. 81 60 75 33 50 56 38 31 _Mo_. 31 20 25 20 40 53 20 40

THE _D_ SET.

A few series of nouns, objects, verbs, and movements dissociated from foreign symbols were obtained. The material was of the same kind as the words used in the couplet series, being mostly monosyllabic and seldom dissyllabic words. They had not been previously used with these subjects. Each series contained ten words or ten objects. The same kind of precautions were taken as in the couplet sets to avoid phonetic aids and the juxtaposition of words which suggest each other.

The apparatus employed in the couplet sets was used. The objects in the object series were shown through the aperture. Visual images were required in the noun and in the verb series. The noun and the object series were exposed at the rate of one word every 2 secs. (or 20 secs.

for the series) for _M_, _S_, and _Hu_, and one every 3 secs. (or 30 secs. for the series) for _B_, _Ho_, and _Mo_. Only one exposure of the series was given. At its completion the subject at once wrote as many of the words or objects as he could recall. Two days later at the same hour he was asked to write without further stimulus as many words of each series as he could recall, cla.s.sifying them according to their type of series.

The verbs were similar to the verbs of the couplet series. There was a tendency in the verb series among most of the subjects to make a more or less connected story of the verbs and thus some subjects could retain all ten words for two days. This was an element not present in the couplet verb series, according to the subjects, nor in any other series, and the subjects were, therefore, directed to eliminate it by imaging each action in a different place and connected with different persons. The effort was nearly successful, some of the subjects connecting two or three verbs, and others none. The movements employed ten objects which were uncovered and covered by the subject as in the _C_ set. The exposure for the verbs and movements was 5 secs. for each word, or 50 secs. for the series. The tests were the same as in the series of ten nouns and ten objects, but in a number of cases (to be specified in the table) it seemed best to shorten the interval for deferred recall to one day.

The series were always given in pairs--a noun and an object series, or a verb and a movement series forming a pair. Only one pair was given per day and no other series of any kind were given on that day.

Usually several days intervened between the II. test of one pair and the learning of the next, but in a little less than half of the cases a new pair was learned on the same day shortly after the II. test of the preceding pair.

The noun-object pairs and the verb-movement pairs were not given in any definite order with reference to each other.

The figures in the following table indicate the number of words out of ten which the subject correctly recalled and placed in their proper columns. Immediate recall is also given.

TABLE VII.

Series. Im. Rec. Two Days. Im. Rec. Two Days.

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

_M._ D^{1-4} 8 9 7 7 7 10 4 5 D^{5-8} 9 7 6 6 8 8 6 6 D^{9-12} 7 7 5 6 8 10 7 7 Av. 24 23 18 19 23 28 17 17

_Mo_.

D^{1-4} 6 6 2 1 8 10 0 7 D^{5-8} 6 5 0 3 8 9 2 4 D^{9-12} 5 7 1 6 10 10 2 7 Av. 17 18 3 10 26 29 4 18

_S_.