Averages 4.1 5.9 4.4 5.6
FEMALES FIRST SERIES SECOND SERIES WHITE BLACK WHITE BLACK
No. 11 5 5 4 6 151 6 4 5 5 215 2 8 2 8 213 2 8 5 5 225 4 6 2 8 227 4 6 6 4 235 6 4 4 6 415 2 8 4 6 425 5 5 8 2 229 2 8 5 5
Averages 3.8 6.2 4.5 5.5
That the dancers should prefer to enter the dark rather than the light box is not surprising in view of the fact that the nests in which they were kept were ordinarily rather dark. But whatever the basis of the preference, it is clear that it must be taken account of in the visual discrimination experiments, for an individual which strongly preferred black might choose correctly, to all appearances, in its first black-white series. Such a result would demonstrate preference, and therefore one kind of discrimination, but not the formation of a habit of choice by discrimination. The preference for black is less marked in the second series of tests because the mouse as it becomes more accustomed to the experiment box tends more and more to be influenced by other conditions than those of brightness. The record sheets for both series almost invariably indicate a strong tendency to continue to go to the left or the right entrance according to the way by which the animal escaped the first time. This cannot properly be described as visual choice, for the mouse apparently followed the previous course without regard to the conditions of illumination. We have here an expression of the tendency to the repetition of an act. It is only after an animal acquires considerable familiarity with a situation that it begins to vary its behavior in accordance with relatively unimportant factors in the situation. It is this fact, illustrations of which may be seen in human life, as well as throughout the realm of animal behavior, that renders it imperative that an animal be thoroughly acquainted with the apparatus for experimentation and with the experimenter before regular experiments are begun. Any animal will do things under most experimental conditions, but to discover the nature and scope of its ability it is necessary to make it thoroughly at home in the experimental situation. As the dancer began to feel at home in the visual discrimination apparatus it began to exercise its discriminating ability, the first form of which was choice according to position.
Since there appears to be a slight preference on the part of most dancers' for the black box in comparison with the white box, white-black training tests were given to fifty mice, and black-white to only four. The tests with each individual were continued until it had chosen correctly in all of the tests of three successive series (thirty tests). As the reproduction of all the record sheets of these experiments would fill hundreds of pages and would provide most readers with little more information than is obtainable from a simple statement of the number of right and wrong choices, only the brightness discrimination records of Tables 6 and 7 are given in full.
As a basis for the comparison of the results of the white-black tests with those of the black-white tests, two representative sets of data for each of these conditions of brightness discrimination are presented (Tables 9 and 10). In these tables only the number of right and wrong choices for each series of ten tests appears.
Tables 9 and 10 indicate—if we grant that the precautionary tests to be described later exclude the possibility of other forms of discrimination— that the dancer is able to tell white from black; that it is somewhat easier, as the preference tests might lead us to expect, for it to learn to go to the black than to the white, and that the male forms the habit of choosing on the basis of brightness discrimination more quickly than the female.
TABLE 9 WHITE-BLACK TESTS
No. 210 No. 215
AGE, 28 DAYS AGE, 28 DAYS
SERIES DATE RIGHT WRONG RIGHT WRONG
(WHITE) (BLACK) (WHITE) (BLACK)
A June 22 4 6 2 8
B 23 4 6 2 8