As it is obvious that knowledge of these subjects is a necessary condition for the intelligent appreciation of the capacities of an animal, as well as of the choice of methods by which it may be trained advantageously, perhaps it is not too much to expect that this investigation of the nature and conditions of educability in the dancing mouse may give us some new insight into the significance of certain aspects of human education and may serve to suggest ways in which we may measure and increase the efficiency of our educational methods.

Merely for the sake of convenience of description I shall cla.s.sify the methods which have been employed as problem methods, labyrinth methods, and discrimination methods. That these names are not wholly appropriate is suggested by the fact that discrimination necessarily occurs in connection with each of them. As problem methods we may designate those tests of initiative and modifiability which involve the opening of doors by pushing or pulling them, and the climbing of an inclined ladder. An example of the labyrinth method has been presented in Chapter XI. The name discrimination method I have applied to those tests which involve the choice of one of two visual, tactual, or olfactory conditions. The white-black discrimination tests, for example, served to reveal the rapidity and permanency of learning as well as the presence of brightness vision.

In the case of most mammals whose educability has been studied experimentally, problem methods have proved to be excellent tests of docility and initiative. The cat, the racc.o.o.n, the monkey, in their attempts to obtain food, learn to pull strings, turn b.u.t.tons, press latches, slide bolts, pull plugs, step on levers. The dancer does none of these things readily. Are we therefore to infer that it is less intelligent, that it is less docile, than the cat, the racc.o.o.n, or the monkey? Not necessarily, for it is possible that these methods do not suit the capacity of the animal. As a matter of fact, all of the tests which are now to be described in their relation to the educability of the dancer bear witness to the importance of the selection of methods in the light of the motor equipment and the habits of the animal which is to be tested.

Judged by ordinary standards, on the basis of results which it yields in problem and labyrinth tests, the dancer is extremely stupid. But that this conclusion is not justified is apparent when it is judged in the light of tests which are especially adapted to its peculiarities.

Problems which are easy for other mammals because of their energetic and persistent efforts to secure food in any way which their motor capacity makes possible are useless as tests of the dancer's abilities, because it is not accustomed to obtain its food as the result of strenuous and varied activities. There are problems and problems; a condition or situation which presents a problem to one organism may utterly lack interest for an organism of different structure and behavior. What is a problem test in the case of the cat or even of the common mouse, is not necessarily a problem for the dancer. Similarly, in connection with the labyrinth method, it is clear that the value of the test depends upon the desire of the organism to escape from the maze. The cat, the rat, the tortoise do their best to escape; the dancer is indifferent. Clearly, then, methods of training should be chosen on the basis of a knowledge of the characteristics of the animal whose educability is to be investigated.

The simplest possible test of the intelligence of the dancer which I could devise was the following. Beside the cage in which the mice were kept I placed a wooden box 26 cm. long, 23 cm. wide, and 12 cm. deep. Neither this box nor the cage was covered, for the animals did not attempt to climb out. As a way of pa.s.sing from one of these boxes to the other I arranged a ladder made of wire fly-screen netting. This ladder was about 8 cm. broad and it extended from the middle of one side of the wooden box upward at an angle of about 30 to the edge of the box and then descended at the same angle into the cage.

A dancer when taken from the nest-box and placed in the wooden box could return to its cage and thus find warmth, food, and company by climbing the ladder. It was my aim to determine, by means of this apparatus, whether the dancers can learn such a simple way of escape and whether they learn by watching one another. As it turned out, a third value belonged to the tests, in that they were used also to test the influence of putting the mice through the act.

In the first experiment three dancers, Nos. 1000, 2, and 6, were together placed in the wooden box. At the end of 15 minutes not one of them had succeeded in returning to the cage. They were then driven to the bottom of the ladder and started upward by the experimenter; with this a.s.sistance all escaped to the nest-box. At the expiration of 5 minutes they were again placed in the wooden box, whence the chilly temperature (about 60 F.) and the lack of food made them eager to return to their cage. No attempt to climb up the ladder was made by any of them within 15 minutes, so the experimenter directed them to the ladder and started them upward as in the first test. This completed the experiment for the day. The following day two tests were given in the same way. In the second of these tests, that is, on its fourth trial, No. 1000 climbed over of his own initiative in 5 minutes. The others had to be a.s.sisted as formerly. On the third day No. 1000 found his way back to the nest-box quickly and fairly directly, but neither No. 2 or No. 6 climbed of its own initiative in the first test. When their movements were restricted to the region of the box about the base of the ladder, both of them returned to the cage quickly.

And on the second test of the third day all the mice climbed the ladder directly.

In Table 35 I have given the time required for escape in the case of 40 tests which were given to these 3 individuals at the rate of 2 tests per day.

When the time exceeded 15 minutes the mice were helped out by the experimenter; a record of 15 minutes, therefore, indicates failure.

Naturally enough the motives for escape were not sufficiently strong or constant to bring about the most rapid learning of which the dancer is capable. Sometimes they would remain in the wooden box washing themselves for several minutes before attempting to find a way of escape. On this account I made it a rule to begin the time record with the appearance of active running about. The daily average time of escape as indicated in the table does not decrease regularly and rapidly. On the fourth day, which was the first on which all three of the dancers returned to the cage by way of the ladder of their own initiative in both tests, the average is 214 seconds. In contrast with this, on the twentieth day the time was only 5 seconds. It is quite evident that the dancers had learned to climb the ladder.

At the end of the twentieth day the experiment was discontinued with Nos.

2 and 6, and after two weeks they were given memory tests, which showed that they remembered perfectly the ladder-climbing act, for when placed in the wooden box, with Nos. 4 and 5 as controls, they returned to the cage by way of the ladder immediately and directly.

TABLE 35

LADDER CLIMBING TEST

Time in Minutes and Seconds

No. of Date No. 1000 No. 2 No. 6 Average Daily Av.

Exp. 1905 For All For All

1 Nov. 14 15' 15' 15' -- -- 2 15' 15' 15' -- --

3 15 15' 15' 15' -- -- 4 300" 15' 15' -- --

5 16 480" 15' 15' -- -- 6 180" 300" 420" 300" 300"

7 17 450" 240" 540" 410"

8 20" 15" 18" 18" 214"

9 18 90" 180" 135" 135"

10 135" 105" 165" 135" 135"

11 19 480" 240" 330" 350"

12 30" 120" 90" 80" 143"

13 20 360" 75" 120" 185"

14 5" 6" 8" 6" 95"

15 21 105" 450" 120" 192"

16 8" 80" 20" 54" 123"

17 22 255" 300" 180" 245"

18 10" 30" 270" 103" 174"

19 23 300" 660" 450" 470"

20 90" 120" 150" 120" 295"

21 24 240" 125" 225" 197"

22 4" 6" 168" 59" 128"

23 Nov. 25 305" 85" 130" 173"

24 5" 6" 118" 43" 108"

25 26 3" 8" 44" 18"

26 19" 1" 176" 98" 58"

27 27 150" 79" 269" 166"

28 26" 3" 31" 20" 93"

29 28 214" 18" 267" 166"

30 40" 3" 4" 16" 91"

31 29 130" 45" 250" 142"

32 12" 3" 25" 13" 77"

33 Dec. 2 61" 35" 44" 47"

34 50" 5" 24" 26" 36"

35 3 66" 18" 2" 29"

36 8" 5" 10" 8" 19"

37 4 9" 4" 3" 5"

38 10" 5" 6" 7" 6"

39 5 5" 3" 5" 4"

40 10" 4" 3" 6" 5"

One of the most interesting and important features of the behavior of the dancer in the ladder experiment was a halt at a certain point on the ladder. It occurred just at the edge of the wooden box at the point where the ladder took a horizontal position, and led over into the cage. Every individual from the first test to the last made this halt. Although from the point of view of the experimenter the act was valueless, it may have originated as an attempt to find a way to escape from the uncomfortable position in which the animal found itself on reaching the top of the ladder. Its persistence after a way of escape had been found is an indication of the nature of habit. Day after day the halt became shorter until finally it was little more than a pause and a turn of the head toward one side of the ladder. I think we may say that in this act we have evidence of the persistence of a particular resolution of physiological states which is neither advantageous nor disadvantageous to the organism.

Had the act resulted in any gain, it would have become more marked and elaborate; had it resulted in injury or discomfort, it would have disappeared entirely. I have observed the same kind of behavior in the frog and in other animals. What the animal begins to do it persists in unless the act is positively harmful or conflicts with some beneficial activity. The only explanation of certain features of behavior is to be found in the conditions of their original occurrence. They persist by sheer force of conservatism. They have value only in the light of the circ.u.mstances under which they first appeared. Although this is merely a fact of habit formation, it suggests that many of the problems which have puzzled students of behavior for ages may be solved by a study of the history of activity.

That there are marked individual differences in intelligence in the dancing mice is apparent from the results of the ladder-climbing experiment. No. 1000 learned to climb quickly, and largely by his own initiative; Nos. 2 and 6, on the contrary, learned only by reason of tuition (being put through the required act by the experimenter). It occurred to me that this experiment, since it was difficult for some individuals and easy for others, might be used to advantage as a test of imitation. If a dancer which knows how to escape to the cage by way of the ladder be placed in the wooden box with one which, despite abundant opportunity, has proved unable to form the habit on his own initiative, will the latter profit by the activity of the former and thus learn the method of escape?