It has been suggested that due to functional similarity, sortal object individuation might be a primordial form of psychological essentialism. For example, the relative independence of identity judgment from perceived surface features is a characteristic of essentialist reasoning. Also, infants engaging in sortal object individuation pay more…

Counting is an evolutionarily recent cultural invention of the human species. In order for humans to have conceived of counting in the first place, certain representational and logical abilities must have already been in place. The focus of this article is the origins and nature of those fundamental mechanisms that promoted the emergence of the…

Recent research suggests that witnessing events of fission (e.g., the splitting of a solid object) impairs human infants', human adults', and non-human primates' object representations. The present studies investigated the reactions of gorillas and orangutans to cohesion violation across different types of fission events implementing a behavioral…

This article presents a tentatively "balanced" view (i.e., midway between lean and rich interpretations) of pointing behavior in infants and apes, based upon the notion of intentional reading of behavior without simultaneous attribution of unobservable mental states. This can account for the complexity of infant pointing without attributing…

This research investigates the development of symbolic or representational play in two species of the genus "Pan", bonobos ("Pan paniscus") and chimpanzees ("Pan troglodytes"). The participants varied not only by species, but also as to whether they had become proficient in communicating with humans via a set of arbitrary visual symbols, called…