Although apes understand others' goals and perceptions, little is known about their understanding of others' emotional expressions. We conducted three studies following the general paradigm of Repacholi and colleagues (1997, 1998). In Study 1, a human reacted emotionally to the hidden contents of two boxes, after which the ape was allowed to…

A nonverbal false belief task was administered to children (mean age 5 years) and two great ape species: chimpanzees ("Pan troglodytes") and bonobos ("Pan paniscus"). Because apes typically perform poorly in cooperative contexts, our task was competitive. Two versions were run: in both, a human competitor witnessed an experimenter hide a reward in…

A milestone in human development is coming to recognize that how something looks is not necessarily how it is. We tested appearance-reality understanding in chimpanzees ("Pan troglodytes") with a task requiring them to choose between a small grape and a big grape. The apparent relative size of the grapes was reversed using magnifying and…

G. Gergely, H. Bekkering, and I. Kiraly (2002) showed that 14-month-old infants imitate rationally, copying an adult's unusual action more often when it was freely chosen than when it was forced by some constraint. This suggests that infants understand others' intentions as rational choices of action plans. It is important to test whether apes…

Compared the abilities of 3 mother-reared and 3 human-raised (enculturated) chimpanzees and 16 human toddlers to imitatively learn novel actions on objects. Found that mother-reared chimpanzees were poorer imitators than both enculturated chimpanzees and human children, who did not differ from one another in imitative learning. On time delay…

Characterizes primate and human forms of sociality and cultural transmission, describing the ontogeny of human cultural learning (joint attention, imitative learning, and cognitive representation). Humans share most cognitive skills and knowledge with other primates, but they also possess a species-unique social cognitive adaptation that enables…

Comments on Gauvain's discussion, in this issue, of the development of thinking from a sociocultural perspective, expanding her analysis by comparing research on apes who have developed in natural habitats with apes raised by humans in something resembling a human culture. Argues that the study of nonhuman primates can contribute to the emerging…

A human demonstrator showed human children and captive chimpanzees how to drag food or toys closer using a rakelike tool. One side of the rake was less efficient than the other for dragging. Chimps tried to reproduce results rather than methods while children imitated and used the more efficient rake side. Concludes that imitation leads to…