Representational Capacities in Chimpanzees: Numerical and Spatial Reasoning

Abstract

The results from these preliminary studies show that chimpanzees are capable of understanding the relationship between a scale model or photographs of the corresponding real space. The results replicate and extend the innovative studies of similar skills in children (e.g., DeLoache, 1987, 1991) to a nonverbal species with whom previous attempts to demonstrate such understanding had failed (Premack and Premack, 1983). However, recognizing these relationships was not necessarily demonstrable in all chimpanzees, as evidenced by the failure of some of the subjects to successfully complete the task. The second study, using a model of the animals’ outdoor enclosure, allowed us to examine the error patterns shown by unsuccessful subjects. Such search patterns differed from those reported for young children (2–1/2 years). The younger children were similarly unable to complete DeLoache’s scale model task but did not show the perseverative search patterns used by the chimpanzees. It may not have been an inability to form a dual orientation that plagued the unsuccessful ape subjects, but rather in the inability to inhibit patterns of deeply rooted behavior. Nonetheless, specified variables that contribute to forming such complex representations as tested in these experiments have not been adequately defined or empirically tested for either human children or for chimpanzees.