Symbolic representation of number in chimpanzees.

This paper aims to summarize the existing evidence for the symbolic representation of number in chimpanzees. Chimpanzees can represent, to some extent, both the cardinal and the ordinal aspect of number. Through the medium of Arabic numerals we compared working memory in humans and chimpanzees using the same apparatus and following the same procedure. Three young chimpanzees outperformed human adults in memorizing briefly presented numerals. However, we found that chimpanzees were less proficient at a variety of other cognitive tasks including imitation, cross-modal matching, symmetry of symbols and referents, and one-to-one correspondence. In sum, chimpanzees do not possess human-like capabilities for representation at an abstract level. The present paper will discuss the constraints of the number concept in chimpanzees, and illuminate some unique features of human cognition.