IV 



RESULTS OF SUPPLEMENTARY TESTS OF IDEATIONAL 

 BEHAVIOR 



1. Julius, Pongo pygmcBUS 

 Box Stacking Experiment 



In addition to the multiple-choice experiments which have 

 been described in detail in the previous section, it was possible 

 to conduct certain less systematic tests of ideational behavior 

 in the monkeys and the orang utan. From, the technical stand- 

 point these tests were relatively unsatisfactory because onl}^ 

 inexactly describable. But their results are in many respects 

 more interesting, if not also more important, in the light which 

 they throw on ideation than are those previously presented. 



First, in order of time, comes a test which may be desig- 

 nated as the box stacking experiment. The method will now 

 be described in connection with an account of the behavior 

 of Julius as contrasted with that of a child of three years and 

 four months of age. 



In the large central cage labelled Z, figure 12, which was 

 twenty -four feet long, ten feet wide, and ten to twelve feet 

 deep, the following situation was arranged. From the center 

 of the wire covering of the cage, a banana was suspended on 

 a string so that it was approximately six feet from the floor, 

 five feet from either side of the cage, and twelve feet from either 

 end. From all approaches it was far beyond the reach of 

 Julius, since it was impossible for him to climb along the wire 

 roof and thus reach the string. Two boxes were placed on 

 the floor of the cage several feet from the point directly under 

 the banana. The one of these boxes was heavy and irregular 

 in shape, as is shown in figures 21, 23 and 24 of plate V. Its 

 greatest height was twenty-one inches; its least height, eighteen 

 inches; its other dimensions, twelve and sixteen inches respec- 

 tively. The smaller and lighter box measured twenty-two by 

 twelve by ten inches. According to the experimenter's calcu- 



