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The Dancing Mouse

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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 passages 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 quantitatively 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, sex, and individuality.

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 classify 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 raccoon, the monkey, in their
attempts to obtain food, learn to pull strings, turn buttons, 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 raccoon, 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 passing 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 assistance
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 assisted 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
circumstances 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?

On November 20, Nos. 4 and 5 were placed in the wooden box and left there
for half an hour. As they had failed to escape at the end of this
interval, they were taken out of the box by the experimenter and returned
to the nest-box. November 21 and 22 this test of their ability to learn to
climb the ladder was repeated with the same result. On November 23 they
were placed in the box with the three mice which had previously been
trained to climb the ladder. The latter escaped at once. Apparently the
attention of Nos. 4 and 5 was drawn to the ladder by the disappearance of
their companions, for they approached its foot and No. 5 climbed up a
short distance. Neither succeeded in escaping, however, and they made no
further efforts that day. On the 24th, and daily thereafter until the
29th, these two dancers were placed in the box for half an hour, with
negative results. At the end of the half hour on the 29th, Nos. 2 and 6
were placed in the box and permitted to go back and forth from one box to
the other repeatedly within sight of Nos. 4 and 5. The latter made no
attempts to follow them, although at times they seemed to be watching
their movements as they ascended the ladder.

To render the results of this test of imitation still more conclusive No.
5 was given further opportunity to learn from No. 1000. Beginning December
2, the following method of experimentation was employed with these two
individuals. They were placed in the wooden box together. No. 1000 usually
climbed out almost immediately. Sometimes No. 5 apparently saw him
disappear up the ladder; sometimes she paid no attention whatever either
to the presence or absence of her companion. After he had been in the
nest-box for a few seconds, No. 1000 was returned to the wooden box by the
experimenter and again permitted to climb out for the benefit of No. 5.
This mode of procedure was kept up until No. 1000 had made from three to
ten trips. No. 5 was left in the box for half an hour each day. This test
was repeated on 18 days within a period of 3 weeks. No. 5 showed no signs
of an imitative tendency, and she did not learn to climb the ladder.

To this evidence of a lack of an imitative tendency in the dancer I may
here add the results of my observations in other experiments. In the
discrimination tests and in the labyrinth tests I purposely so arranged
conditions, in certain instances, that one individual should have an
opportunity to imitate another. In no case did this occur. Seldom indeed
did the animals so much as follow one another with any considerable degree
of persistence. They did not profit by one another's acts.

Excellent evidence in support of this conclusion was furnished by the
behavior of the mice in the discrimination experiments. Some individuals
learned to pull as well as to push the swinging wire doors of the
apparatus and were thus enabled to pass through the doorways in either
direction; other individuals learned only to pass through in the direction
in which the doors could be pushed open. Naturally I was interested to
discover whether those which knew only the trick of opening the doors by
pushing would learn to pull the doors or would be stimulated to try by
seeing other individuals do so. At first I arranged special tests of
imitation in the discrimination box; later I observed the influence of the
behavior of one mouse upon that of its companion in connection with visual
discrimination experiments. This was made possible by the fact that
usually a pair of individuals was placed in the discrimination box and the
tests given alternately to the male and to the female. Both individuals
had the freedom of the nest-box and each frequently saw the other pass
through the doorway between the nest-box, _A_, and the entrance chamber,
_B_ (Figure 14), either from _A_ to _B_ by pushing the swing door or from
_B_ to _A_ by pulling the door.

Although abundant opportunity for imitation in connection with the opening
of the doors in the discrimination box was given to twenty-five
individuals, I obtained no evidence of ability to learn by imitation. The
dancers did not watch the acts which were performed by their companions,
and in most instances they did not attempt to follow a mate from nest-box
to entrance chamber.

These problem tests, simple as they are, have revealed two important facts
concerning the educability of the dancer. First, that it does not learn by
imitation to any considerable extent, and, second, that it is aided by
being put through an act. Our general conclusion from the results of the
experiments which have been described in this chapter, if any general
conclusion is to be drawn thus prematurely, must be that the dancing mouse
in its methods of learning differs markedly from other mice and from rats.




CHAPTER XIII

HABIT FORMATION: THE LABYRINTH HABIT

The problem method, of which the ladder and door-opening tests of the
preceding chapter are examples, has yielded interesting results concerning
the individual initiative, ingenuity, motor ability, and ways of learning
of the dancer; but it has not furnished us with accurate measurements of
the rapidity of learning or of the permanency of the effects of training.
In this chapter I shall therefore present the results of labyrinth
experiments which were planned as means of measuring the intelligence of
the dancer.

The four labyrinths which have been used in the investigation may be
designated as _A, B, C,_ and _D_. They differ from one another in the
character of their errors, as well as in the number of wrong choices of a
path which the animal might make on its way from entrance to exit. In the
use of the labyrinth method, as in the case of the discrimination method
of earlier chapters, the steps by which a satisfactory form of labyrinth
for testing the dancer was discovered are quite as interesting and
important for those who have an intelligent appreciation of the problems
and methods of animal psychology as are the particular results which were
obtained. For this reason, I shall describe the various forms of labyrinth
in the order in which they were used, whether they proved satisfactory or
not. At the outset of this part of my investigation, it was my purpose to
compare directly the capacity for habit formation in the dancer with that
of the common mouse. This proved impracticable because the same labyrinth
is not suited to the motor tendencies of both kinds of mice.

[Illustration: FIGURE 25.--Labyrinth A. _I_. entrance; _O_, exit; 1, 2, 3,
4, blind alleys.]

The first of the four labyrinths, A, appears in ground plan in Figure 25.
It was constructed of wood, as were the other labyrinths also, and
measured 60 cm. in length and width, and 10 cm. in depth. The outside
alleys were 5 cm. wide. In the figure, _I_ marks the starting point or
entrance to the maze, and _O_ the exit through which the mouse was
permitted to pass into its nest-box. Any turn in the wrong direction which
the animal made in its progress from entrance to exit was recorded as an
error. The four errors, exclusive of the mistake of turning back, which
were possible in this labyrinth, are indicated in the figure by the
numerals 1, 2, 3, and 4. By retracing its steps a mouse might repeat any
one or all of these errors, and add to them the error of turning back.

In the experiments a mouse was permitted to enter the maze from a small
box which had been placed by the experimenter at _I_, and an accurate
record was kept of the number of errors which it made in finding its way
from entrance to exit, and of the time occupied. Each of five dancers was
given 31 tests in this labyrinth. The number of tests per day varied, as
is indicated in Table 36, from 1 to 4. The results of the tests, so far as
errors and times are in question, appear in the table. _T_ at the head of
a column is an abbreviation for time, _E_ for errors.

The dancers did not learn to escape from this labyrinth easily and
quickly. In fact, the average time of the thirty-first test (198") is
considerably longer than that of the first (130"). The number of errors
decreased, it is true, but even for the last test it was 6.6 as compared
with only a little more than twice that number for the first test. The
last column of the table furnishes convincing proof of the truth of the
statement that the animals did not acquire a perfect labyrinth-A habit.
Was this due to inability to learn so complex a path, or to the fact that
the method is not adapted to their nature? Observation of the behavior of
the mice in the experiments enables me to say with certainty that there
was no motive for escape sufficiently strong to establish a habit of
following the direct path. Often, especially after a few experiences in
the maze, a dancer would wander back and forth in the alleys and central
courts, dancing much of the time and apparently exploring its surroundings
instead of persistently trying to escape. This behavior, and the time and
error results of the accompanying table, lead me to conclude that the
labyrinth method, as it has been employed in the study of the intelligence
of several other mammals, is not a satisfactory test of the ability of the
dancer to profit by experience. That the fault is not in the labyrinth
itself is proved by the results which I obtained with common mice.

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