MENTAL LIFE OF MONKEYS AND APES 49 



lem was near at hand. This fact the experimenter recorded 

 in his daily notes, and sure enough, on the following day Sobke 

 chose correctly throughout the series of ten trials. The time 

 for this series was only ten minutes. The choices were made 

 deliberately and readily. 



An analysis of the data of table 5 reveals five methods or 

 reactive tendencies which appeared more or less definitely in 

 the following order: (a) Choice of first box at the left, because 

 of experience in problem 1. This tendency w^as very quickly 

 suppressed by the requirements in connection with problem 2. 

 Indeed one of the most significant differences which I have dis- 

 covered between the behavior of the primates and that of other 

 mammals is the time required for the suppression of such an 

 acquired tendency. The monkey seems to learn almost imme- 

 diately that it is not worth while to persist in a tendency which 

 although previously profitable no longer yields satisfaction, 

 whereas in the crow, pig, rat, and ring dove, the unprofitable 

 mode of response tends to persist during a relatively large 

 number of trials, (b) The tendency to choose, first, a box near 

 the left end of the group, to go from that to the box at the 

 extreme right end of the group, thence to the one next in order, 

 which was, of course, the right box. This tendency appears 

 fairly clearly from May 7th on. (c) The box at the extreme 

 right was first chosen and then the one next to it. For example, 

 in setting 2, box 4 would be chosen first, then box 3. Or, if 

 this did not occur, the method previously described under (b) 

 was likely to be employed, as for example, in setting 8, where 

 such choices as 7.6.5.1.8 appear, (d) In certain series there 

 appeared a marked preference for a particular box, usually 

 box 3 (see results for May 24). This was doubtless due in a 

 measure, if not wholly, to the fact that box 3 was the right box 

 twice in each series of ten settings. But it should be added that 

 the same is true of box 7, for which no preference was mani- 

 fested at any time, (e) Direct choice of the right box. 



The five reactive methods or tendencies enumerated above 

 roughly appeared in the order named, but there were certain 

 irregularities and the order as well as the time of appearance 

 varied somewhat from setting to setting. In general, method 

 c was the most frequently used prior to the development of 

 method e, the direct choice of the right box. 



