EVIDENCES OF INSIGHT 45 



feat which was impossible because the bottom of the bottle 

 was larger than the top. It was only after two or three 

 hard-won successes in attaining the reward that Chim took 

 to turning the box up and pulling the bottle out from beneath. 

 This method, I think, was achieved rather by accident than 

 by insight. At any rate the animal 's behavior did not sug- 

 gest the effective use of ideas. 



A method which both Koehler and the writer have used 

 to advantage in testing anthropoid ideation is the so-called 

 *'box stacking test." A young orang-utan tested with 

 this method achieved success only on the basis of imitation. 

 Certain chimpanzees observed by Koehler, on the contrary, 

 stacked boxes spontaneously and with considerable skill 

 in order to obtain suspended banana. It must not be for- 

 gotten, however, that Koehler 's animals were much older 

 than Chim and Panzee. 



The setting of the box stacking experiment may be briefly 

 described as follows: A light strong cord was attached to the 

 ceiling of a room approximately 8 feet high.. The nearest 

 point from which the animal could reach toward this cord 

 was more than 5 feet distant. To the cord a banana was 

 attached at distances from the floor ranging from approxi- 

 mately 150 to 200 cm. Three boxes were provided for the 

 animal's possible use, each with one open side. The boxes 

 differed in size in accordance with the following dimensions: 

 no. 1, 16 by 12 by 11 inches (one 16 by 12 side open); no. 2, 

 16 by 10 by 9 inches (one 16 by 10 side open); no. 3, 11 by 11 

 by 10 inches (one 11 by 11 side open). These boxes were 

 placed on the floor of the room within convenient reach of 

 the string, but so far from it that the animal could neither 

 reach from them nor spring from them to the reward without 

 moving them. 



