Abstract
The purpose of this study was to determine if a Piagetian-type multiple-classification task could be used to evaluate the cognitive capacities of juvenile chimpanzees (Pan troglodytes). On this task the animals were required to select the correct object from the response tray and place it inside the empty cell of the stimulus matrix that was formed by crossing two different colors with two different shapes. By the end of testing the nonhuman primates were able to solve the unique multiple-classification problems by selecting significantly more often objects that were correct on both color and shape cues (C +/S+), as compared to the other choice responses of color only (C+/S—), shape only (C—/S+), or neither stimulus correct (C—/S—). The response strategy of selecting C+/S+ choice objects may have appeared as the juvenile great apes learned to scan the stimulus items in the matrix visually, and response tray, and attend to color and shape cues. The use of Piagetian-type tasks to assess the cognitive capacities of human and nonhuman primates is discussed.