Stimulus Relations in Comparative Primate Perspective

Nonhuman primates have demonstrated the ability to learn a variety of stimulus-stimulus relations. Lexigram-word linguistic systems with juvenile pygmy chimpanzees (Pan paniscus) have disclosed incidental learning of relations between lexigrams, objects, and spoken English. Chimpanzees (Pan troglodytes) have shown equivalence relations in which “food” and “tool” lexigrams were used to categorize other lexigrams. The latter subjects also showed evidence of generalized learning strategies such as “learning by exclusion.” The discussion of these findings focuses on developmental and species factors that seem critical to their development.