ACQUISITION OF FUNCTIONAL SYMBOL USAGE IN APES AND CHILDREN
E. Sue Savage-Rumbaugh Emory University
One of the more striking differences in the symbolic behavior reported for chimpanzees and young children (at the one word stage) is the apparent absence of any sort of indicative or declarative symbol usage on the part of the chimpanzees ( Terrace, Petitto, Sanders, & Bever, 1979) Chimpanzees do not seem to use symbols to declare or indicate what they are about to do or to draw the attention of others to objects of interest For example, after working with Nim, Terrace observed that
The function of the symbols of an ape's vocabulary appears to be not so much to identify things or to convey information as, for example, [Skinner's concept of "tacts"] as it is to satisfy a demand that it use that symbol in order to obtain some reward [Skinner's concept of "mands"] ( Terraceet al., 1979, p. 900).
Terraceof al. ( 1979) are not alone in this view. The overriding theme of the reports which describe symbol usage in apes ( Gardner & Gardner, 1975; Miles, 1976; Patterson, 1978; Premack, 1976; Rumbaugh & Gill, 1976) suggest that the two basic contexts of chimpanzee-produced symbols are requesting desired objects and associatively labeling objects displayed by the experimenter.
Why should the circumstances in which chimpanzees typically employ symbols seem to center on their immediate physical desires and their responses to questions by their teachers ( Gardner & Gardner, 1975; Sanders, 1980) while symbols are employed by children to describe what they do, to draw attention to what they are looking at, as well as to request things which they need? Is this difference merely a function of the fact that human beings are a more open and sharing species while chimpanzees are very self-centered as those who have worked with apes suggest ( Premack, 1976; Rumbaugh & Gill, 1976; Terraceet al., 1979)?
The suggestion offered here is that this difference is not a function of species specific tendencies alone. Rather, it obtains because of how symbols are taught to apes. Chimpanzees do not acquire symbols on their own, as do human children and the molding-modeling method used by most ape-language researchers encourages associative-imitative symbol usage. It is by no means clear that apes are able to make the transition