D^{1-4} 8 9 2 3 9 10 6 9 D^{5-8} 8 10 2 4 9 10 4 9 D^{9-12} 8 10 2 5 8 10 3 7 Av. 24 29 6 12 26 30 13 25

_Hu._ D^{1-4} 6 8 3 7 9 10 4 9 D^{5-8} 7 9 0 2 9 10 2 7 D^{9-12} 7 9 4 6 8 10 1 8 Av. 20 26 7 15 26 30 7 24

_Ho._ D^{1-4} 9 9 3 3 10 9 5 7 D^{5-8} 9 8 1 6 9 9 6 8 D^{9-12} 8 8 5 5 10 10 6 7 Av. 26 25 9 14 29 28 17 22

One day.

The results of the _D_ set strongly confirm the results of the _A_, _B_, and _C_ sets. Table VII. shows that after from one to two days'

interval four subjects recall objects better than nouns and movements better than verbs. One subject, _M._, shows no preference.

CONCLUSIONS.

We are now in a position to answer specifically the problem of this investigation. The results show: (1) that those five subjects who recall objects better than nouns (involving images) _when each occurs alone_, also recall objects better than nouns when each is recalled by means of an unfamiliar verbal symbol with which it has been coupled; (2) that the same is true of verbs and movements; (3) that these facts also receive confirmation on the negative side, viz.: the one subject who does not recall objects and movements better than nouns and verbs (involving images) _when they are used alone_, also does not recall them better _when they are recalled by means of foreign symbols_ with which they have been coupled.

MINOR QUESTIONS.

The problem proposed at the outset of the investigation having been answered, two minor questions remain: (1) as to images, (2) indirect a.s.sociations.

1. All the subjects were good visualizers. The images became clear usually during the first of the three presentations, _i.e._, in 1-3 secs., and persisted until the next couplet appeared. In the second and third presentations the same images recurred, rarely a new one appeared.

An interesting side light is thrown on M.'s memory by his work in another experiment in which he was a subject. This experiment required that the subject look at an object for 10 secs. and then after the disappearance of its after-image manipulate the memory image. M.

showed unusually persistent after-images. The memory images which followed were unusually clear in details and also persistent. They were moreover retained for weeks, as was shown by his surprising ability to recall the details of an image long past, and separated from the present one by many subsequent images. His memory was capacious rather than selective. His eyesight was tested and found to be normal for the range of the apparatus. Possibly his age (55 yrs.) is significant, although one of the two subjects who showed the greatest preference for objects and movements, Mo., was only six yrs.

younger. The ages of the other subjects were S. 36 yrs., Hu. 23 yrs., B. 25 yrs., Ho. 27 yrs.

That some if not all of the subjects did not have objective images in many of the noun and verb couplets if they were left to their own initiative to obtain them is evident from the image records in the _A_ set, in which the presence of the objective images was optional but the record obligatory. The same subject might have in one noun or verb series no visual images and in another he might have one for every couplet of the series. After the completion of the _A_ set, the effect of the presence of the objective images in series of 10 nouns alone, or 10 objects alone after two days' interval, was tested. This was merely a repet.i.tion of similar work by Kirkpatrick after three days'

interval, and yielded similar results. As a matter of fact some of the subjects were unable wholly to exclude the objective images, but were compelled to admit and then suppress them as far as possible, so that it is really a question of degree of prominence and duration of the images.

The presence of the objective images having been shown to be an aid in the case of series of nouns, the subjects were henceforth requested to obtain them in the noun and verb series of the _B_ and _C_ sets, and the image records show that they were entirely successful in doing so.

2. The total number of couplets in any one or in several sets may be divided into two cla.s.ses: (1) Those in which indirect a.s.sociations did not occur in the learning, and (2) those in which they did occur. For reasons already named we may call the first pure material and the second mixed. We can then ascertain in each the proportion of correctly recalled couplets after one, two, nine and sixteen days'

interval, and thus see the importance of indirect a.s.sociations as a factor in recall. This is what has been done in the following table.

The figures give the number of couplets correctly or incorrectly recalled out of 64. In the case of the interval of one day the figures are a tabulation of the III. test (twenty-one hours) of the _C_ set, which contained 16 series of 4 couplets each. The figures for the intervals of two, nine and sixteen days are a tabulation of the _B_ set, which also contained 16 series of 4 couplets each. _C_ denotes correct, _I_ incorrect.

TABLE VIII.

SHOWING GREATER PERMANENCE OF COUPLETS IN WHICH INDIRECT a.s.sOCIATIONS OCCURRED.

Pure Material. Mixed Material.

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

C I C I C I C I C I C I C I C I _M._ 40 22 23 39 22 40 2 0 2 0 3 0 _Mo._ 36 22 31 27 29 29 6 0 6 0 5 1 _S._ 27 34 6 55 2 59 1 60 2 1 3 0 3 0 3 0 _Hu._ 35 22 16 45 5 56 4 57 6 1 3 0 3 0 3 0 _B._ 48 16 17 43 9 51 7 53 0 0 4 0 1 3 1 3 _Ho._ 37 15 17 30 13 36 3 46 10 2 9 6 8 7 7 8

Total: 147 87 132 217 83 268 66 285 18 4 27 6 23 10 21 12 P'c't.: 63 37 38 62 24 76 19 81 82 18 82 18 70 30 64 36

We see from the table that the likelihood of recalling couplets in which indirect a.s.sociations did not occur in learning is 63 per cent.

after one day, and that there is a diminution of 44 per cent. in the next fifteen days. The fall is greatest during the second day. On the other hand, the likelihood of recalling couplets in which indirect a.s.sociations did occur is 82 per cent. after one day, and there is a diminution of only 18 per cent. during the next fifteen days. The fading is also much more gradual.

It is evident, then, that in all investigations dealing with language material the factor of indirect a.s.sociations--a largely accidental factor affecting varying amounts of the total material (in these six subjects from 3 per cent. to 23 per cent.) is by far the most influential of all the factors, and any investigations which have heretofore failed to isolate it are not conclusive as to other factors.

The practical value of the foregoing investigation will be found in its bearing upon the acquisition of language. While it is by no means confined to the acquisition of the vocabulary of a _foreign_ language, but is also applicable to the acquisition of the vocabulary of the native language, it is the former bearing which is perhaps more obvious. If it is important that one become able as speedily as possible to grasp the meaning of foreign words, the results of the foregoing investigation indicate the method one should adopt.

MUTUAL INHIBITION OF MEMORY IMAGES.

BY FREDERICK MEAKIN.

The results here presented are the record of a preliminary inquiry rather than a definitive statement of principles.

The effort to construct a satisfactory theory of inhibition has given rise, in recent years, to a good deal of discussion. Ever since it was discovered that the reflexes of the spinal cord are normally modified or restrained by the activity of the brain and Setschenow (1863) attempted to prove the existence of localized inhibition centers, the need of such a theory has been felt. The discussion, however, has been mainly physiological, and we cannot undertake to follow it here. The psychologist may not be indifferent, of course, to any comprehensive theory of nervous action. He works, indeed, under a general presumption which takes for granted a constant and definite relation between psychical and cerebral processes. But pending the settlement of the physiological question he may still continue with the study of facts to which general expression may be given under some theory of psychical inhibition not inconsistent with the findings of the physiologist.

A question of definition, however, confronts us here. Can we, it may be asked, speak of psychical inhibition at all? Does one conscious state exercise pressure on another, either to induce it, or to expel it from the field? 'Force' and 'pressure,' however pertinent to physical inquiries, are surely out of place in an investigation of the relations between the phenomena of mind. Plainly a distinction has to be made if we are to carry over the concept of inhibition from the domain of nervous activity to the conscious domain. Inhibition cannot, it should seem, have the same sense in both. We find, accordingly, that Baldwin, who defines nervous inhibition as 'interference with the normal result of a nervous excitement by an opposing force,' says of mental inhibition that it 'exists in so far as the occurrence of a mental process prevents the simultaneous occurrence of other mental processes which might otherwise take place.'[1]

[1] Baldwin, J.M.: 'Dictionary of Philosophy and Psychology,'

New York and London, 1901, Vol. I., article on 'Inhibition.'

Even here, it may be said, there is in the term 'prevents' an implication of the direct exercise of force. But if we abstract from any such implication, and conceive of such force as the term inhibition seems to connote, as restricted to the a.s.sociated neural or physiological processes, no unwarranted a.s.sumptions need be imported by the term into the facts, and the definition may, perhaps, suffice.

Some careful work has been done in the general field of psychical inhibition. In fact, the question of inhibition could hardly be avoided in any inquiry concerning attention or volition. A. Binet[2]

reports certain experiments in regard to the rivalry of conscious states. But the states considered were more properly those of attention and volition than of mere ideation. And the same author reports later[3] examples of antagonism between images and sensations, showing how the latter may be affected, and in some respects inhibited, by the former. But this is inhibition of sensations rather than of ideas. Again, Binet, in collaboration with Victor Henri,[4]

reports certain inhibitory effects produced in the phenomena of speech. But here again the material studied was volitional. More recently, G. Heymans[5] has made elaborate investigation of a certain phase of 'psychische Hemmung,' and showed how the threshold of perception may be raised, for the various special senses, by the interaction of rival sensations, justly contending that this shifting of the threshold measures the degree in which the original sensation is inhibited by its rival. But the field of inquiry was in that case strictly sensational. We find also a discussion by Robert Saxinger,[6]

'Ueber den Einfluss der Gefuhle auf die Vorstellungsbewegung.' But the treatment there, aside from the fact that it deals with the emotions, is theoretical rather than experimental.

[2] Binet, A.: _Revue Philosophique_, 1890, XXIX., p. 138.

[3] Binet, A.: _Revue Philosophique_, 1890, x.x.x., p. 136.

[4] Binet, A., et Henri, V.: _Revue Philosophique_, 1894, x.x.xVII., p. 608.

[5] Heymans, G.: _Zeitschrift f. Psych. u. Physiol. d.

Sinnesorgane_, 1899, Bd. XXI., S. 321; _Ibid._, 1901, Bd.

XXVI., S. 305.

[6] Saxinger, R.: _Zeitschrift f. Psych. u. Physiol. d.

Sinnesorgane_, 1901, Bd. XXVI., S. 18.