Picture Memory in the Chimpanzee

Abstract

Complex cognitive functioning of chimpanzees on tasks with 5 relational cues was reexamined, and a new hypothesis (picture-memory) was presented involving the memorization of a list of stimuli each of which was rewarded if, and only if, it was presented within a particular stimulus configuration. The first experiment demonstrated the picture-memory hypothesis by showing successful performance on a 4-choice discrimination task which was essentially a match-to-sample task without the presence of the sample. In the second experiment, the picture-memory hypothesis was examined in more detail by omitting part of the total stimulus configuration and measuring the resultant performance decrement. It was concluded that loss of stimuli proximal to the rewarded stimulus interfered with the picture-memory behavior more than the loss of distal stimuli, but the behavior was most seriously disrupted by the loss of the rewarded stimuli. In the third experiment, the total stimulus configuration was tested by presenting the mirror image of the original pictures. The inability of the chimpanzees to generalize immediately to the reversal of the original stimulus configurations was demonstrated, and it was concluded that the mirror-image stimuli were, in essence, new pictures to be memorized.