TEST CONDITION ERRORS CONDITION ERRORS

I. 1 No shock 9 I. No shock 2

II. 2 Shock 5 II. Shock 3 3 Shock 4 Shock 1 4 Shock 2 Shock 0 5 Shock 3 Shock 0 6 Shock 0 Shock 0 7 Shock 0 Shock 0 8 Shock 0 Shock 0

9 Shock 0 III. Labyrinth 0 moved

10 Shock 0 IV. Paper on floor 4

III. 11 Labyrinth 0 No paper (shock) 0 moved

IV. 12 Paper on 0 0 floor 13 No paper 0 No paper 0 (shock) 14 Paper 1 Paper 1 15 No paper 0 No paper 0 16 Paper 7 Paper 4 17 No paper 0 No paper 0 18 Paper 0 Paper 0 19 No paper 0 No paper 0 20 Paper 4 Paper 0 21 No paper 0 No paper 0 22 Paper 2 V. Darkness 0 23 No paper 2 VI. Labyrinth 2 24 Paper 1 washed 0 25 No paper 0 VII. Darkness 2 26 Paper 0 27 No paper 0 28 Paper 0 29 No paper 0 V. 30 Darkness 0 VI. 31 Labyrinth 2 washed 32 0 VII. 33 Darkness 0

The average results for the twelve individuals (six of each s.e.x) which were subjected to the tests, I have arranged in Table 34. The Roman numerals at the top of the table designate the seven groups of tests, and the figures under each, the numerical results of the tests. I may explain and comment upon the averages of the several columns of this table in turn.

Column I gives the number of errors made in the preliminary test.

Curiously enough, the males made many more errors than the females.

For the second group of tests (II) two results have been tabulated: the number of the first correct test, and the total number of tests before the path was followed correctly five times in succession. The first correct trip came usually after not more than five or six tests, but five successive correct trips demanded on the average at least fourteen training tests.

Destruction of the floor path by movement of the labyrinth to one side, without changing its relations to the points of the compa.s.s, disturbed the mice very little. Only four of the twelve individuals made any mistakes as a result of the change in the tactual conditions, and the average error as it appears in Column III is only .3.

TABLE 34

ROLE OF SIGHT, TOUCH, AND SMELL IN LABYRINTH EXPERIMENTS

II. IV.

TRAINING TESTS SMOKED I. NO OF TESTS BEFORE III. PAPER ON MALES PRELIMINARY CORRECT LABYRINTH FLOOR TEST. _____________________ MOVED. NO OF TIMES ERRORS FIRST TIME FIVE TIMES ERRORS BEFORE COR- RECT TWICE

210 9 5 9 0 9 212 2 3 8 1 3 214 6 10 28 0 22 220 25 4 8 0 14 410 11 6 20 0 10 420 14 6 14 1 7

AVERAGES 11.2 5.7 14.5 .3 10.8

FEMALES

211 16 6 10 1 5 213 7 5 14 1 21 215 2 3 7 0 6 225 14 6 18 0 14 415 6 6 13 0 3 425 10 7 13 0 8

AVERAGES 9.2 5.5 12.5 .3 9.5

V.

DARKNESS VI.

MALES LABYRINTH VII.

ERRORS IN NO. OF TESTS WASHED. DARKNESS.

FIRST TEST BEFORE COR'CT ERRORS ERRORS

210 0 1 2 0 212 2 2 0 0 214 0 1 -- 0 220 2 4 2 0 410 1 3 2 1 420 2 4 1 4

Averages 1.2 2.5 1.2 0.8

FEMALES

211 2 2 0 0 213 2 2 -- 3 215 0 1 2 2 225 3 2 0 0 415 1 3 2 1 425 1 7 0 0

Averages 1.5 2.8 0.7 1.0

That covering the floor with smoked paper forced the mice to relearn the path, in large measure, is evident from the results of Column IV. An average of ten tests was necessary to enable the mice to follow the path correctly. It is almost certain, however, that the interference with the perfectly formed labyrinth habit which this change in the condition of the floor caused was not due to the removal of important tactual sense data.

As Column V shows, the number of errors in total darkness is very small.

Some individuals gave no sign of being disturbed by the absence of visual guidance, others at first seemed confused. I have given in the table the number of errors in the first darkness test and the number of the first test in which no mistakes occurred.

No more disturbance of the dancer's ability to follow the path which it had learned resulted from washing the labyrinth thoroughly than from darkening the room. Indeed it is clear from Column VI that the path was not followed by the use of smell. However, the test in darkness, after the odor of the box had been removed, proved conclusively that in most cases the mice could follow the path correctly without visual or olfactory guidance.

The behavior of 18 individuals as it was observed in labyrinth B makes perfectly evident three important facts, (1) In following the path which it has learned, the dancer in most instances is not guided to any considerable extent by a trail (odor or touch) which has been formed by its previous journeys over the route; (2) sight is quite unnecessary for the easy and perfect execution of the labyrinth habit, for even those individuals which are at first confused by the darkening of the experiment room are able after a few tests to follow the path correctly; (3) and, finally, smell, which according to current opinion is the chiefly important sense of mice and rats, is not needful for the performance of this habitual act.

At this point we may very fittingly ask, what sense data are necessary for the guidance of the series of acts which const.i.tutes the labyrinth habit?

I answer, probably none. A habit once formed, the senses have done their part; henceforth it is a motor process, whose initiation is conditioned by the activity of a receptive organ (at times a sense receptor), but whose form is not necessarily dependent upon immediate impressions from eye, nose, vibrissae, or even from internal receptors. These are statements of my opinion; whether they express the truth, either wholly or in part, only further experimentation can decide.

In considering the results of these labyrinth tests it is important that we distinguish clearly those which have to do with the conditions of habit formation from those which instead have to do with the conditions of habit performance. Sense data which are absolutely necessary for the learning of a labyrinth path may be of little or no importance for the execution of the act of following the path after the learning process has been completed. Thus far in connection with the labyrinth tests we have discussed only the relations of sight, touch, and smell to what I have called habit performance. We may now ask what part these senses play in the formation of a labyrinth habit.

A very definite answer to this question is furnished by observation of the behavior of the dancers in the tests. Most of them continuously made use of their eyes, their noses, and their vibrissae. Some individuals used one form of receptive organ almost exclusively. I frequently noticed that those individuals which touched and smelled of the labyrinth pa.s.sages most carefully gave least evidence of the use of sight. It is safe to say, then, that under ordinary conditions habit formation in the dancer is conditioned by the use of sight, touch, and smell, but that these senses are of extremely different degrees of importance in different individuals.

And further, that, although in the case of some individuals the loss of sight would not noticeably delay habit formation, in the case of others it would seriously interfere with the process. When deprived of one sense, the dancer depends upon its remaining channels of communication with environment. Indeed there are many reasons for inferring that if deprived of sight, touch, and smell it would still be able to learn a labyrinth path; and there are reasonable grounds for the belief that a habit once formed can be executed in the absence of all special sense data.

Apparently the various receptive organs of the body furnish the dancer with impressions which serve as guides to action and facilitate habit formation, although they are not necessary for habit performance.

The reader may wonder why I have not carried out systematic experiments to determine accurately and quant.i.tatively the part which each sense plays in the formation of a labyrinth habit instead of basing my inferences upon incidental observation of the behavior of the dancers. The reason is simply this: the number and variety of experiments which were suggested by the several directions in which this investigation developed rendered the performance of all of them impossible. I have chosen to devote my time to other lines of experimentation because a very thorough study of the conditions of habit formation has recently been made by Doctor Watson.[1]

[Footnote 1: Watson, J. B., _Psychological Review_, Monograph Supplement, Vol. 8, No. 2, 1907.]

What is the role of sight in the dancing mouse? How shall we answer the question? The evidence which has been obtained in the course of my study of the animal indicates that brightness vision is fairly acute, that color vision is poor, that although form is not clearly perceived, movement is readily perceived. My observations under natural conditions justify the conclusion that sight is not of very great importance in the daily life of the dancer, and my observations under experimental conditions strongly suggest the further conclusion that movement and changes in brightness are the only visual conditions which to any considerable extent control the activity of the animal.

CHAPTER XII

EDUCABILITY: METHODS OF LEARNING

Nearly all of the experiments described in earlier chapters have revealed facts concerning the educability of the dancer. In order to supplement the knowledge of this subject thus incidentally gained and to discover the principles of educability, the specially devised experiments whose results appear in this and succeeding chapters were arranged and carried out with a large number of mice. In the work on the modifiability of behavior I have attempted to determine (1) by what methods the dancer is capable of profiting by experience, (2) the degree of rapidity of learning, (3) the permanency of changes wrought in behavior, (4) the effect of one kind of training upon others, (5) the relation of re-training to training, and (6) the relation of all these matters to age, s.e.x, and individuality.