Deferred imitation of object-related actions in human-reared juvenile chimpanzees and orangutans

Deferred imitation of object-related actions (e.g., picking up a cloth with a set of tongs) was assessed in 3 enculturated juvenile orangutans (Pongo pygmaeus) and 3 enculturated juvenile chimpanzees (Pan troglodytes). For each task, animals were given 4 min to explore th objects (baseline), followed by a demonstration of the target behavior, and 10 min later, were re-presented the objects (deferred phase). Each animal displayed deferred imitation on at least one trial, with each species demonstrating deferred imitation on approximately half of all possible trials. The findings were interpreted as reflecting cognitive abilities in juvenile great apes that permit deferred imitation under humanlike rearing conditions. (C) 2000 John Wiley & Sons, Inc.