ABSTRACT
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”] (Terrace et al., 1979, p. 900).
