In the descriptions of the various visual experiments of this and the following chapters, the first word of the couplet which describes the condition of the experiment, for example, white-black, always designates the visual condition which the animal was to choose, the second that which it was to avoid on penalty of an electric shock. In the case of Tables 6 and 7, for example, white cardboard was placed in one box, black in the other, and the animal was required to enter the white box. In the tables the first column at the left gives the number of the test, the second the positions of the cardboards, and the third and fourth the result of the choice. The first test of Table 6 was made with the white cardboard on the box which stood at the left of the mouse as it approached from _A_, and, consequently, with the black cardboard on the right. As is indicated by the record in the "wrong" column, the mouse chose the black instead of the white. The result of this first series was choice of the white box four times as compared with choice of the black box six times. On the eleventh day, that is, after No. 5 had been given 100 tests in this brightness vision experiment, she made no mistakes in a series of ten trials (Table 7). TABLE 6 BRIGHTNESS DISCRIMINATION White-Black, Series 1 Experimented on No. 5 January 15, 1906 POSITION OF TEST CARDBOARDS RIGHT WRONG 1 White left -- Wrong 2 White right -- Wrong 3 White left -- Wrong 4 White right -- Wrong 5 White left Right -- 6 White right Right -- 7 White left -- Wrong 8 White right Right -- 9 White left -- Wrong 10 White right Right -- Totals 4 6