Communication, symbolic communication, and language: Comment on Savage-Rumbaugh, McDonald, Sevcik, Hopkins, and Rupert (1986).

Abstract

Savage-Rumbaugh, McDonald, Sevcik, Hopkins, and Rupert's (1986) description of their pygmy chimpanzees' behavior raises many interesting questions about what they have learned. Their behavior is communicative, but is it and how does it relate to the child's use oflanguage? SavageRumbaugh et al, interpreted this behavior as symbolic communication. However, this interpretation does not account for significant aspects of the apes' performance. For example, Kanzi's performance on the vocabulary test differed greatly from his performance in naturalistic exchanges, which would not have been expected if he had in fact learned that lexigrams are symbols. The apes' performance is consistent with the hypothesis that they have learned the instrumental functions of lexigrams in the experimental context. That is, they use lexigrams to mediate the receipt of desired outcomes such as food or travel. This behavior, which Skinner (1957) termed manding, does not require knowledge of words or symbols at all. The apes' use oflcxigrams appears to be more like the nonlinguistic gestural of very young children than the use of full lexical items. The dichotomy between the apes' linguistic and cognitive capacities is discussed in terms of implications concerning the possible species specificity oflanguage. Savage-Rumbaugh, McDonald, Sevcik, Hopkins, and Rupert (1986) reported intriguing results from an ongoing study of two pygmy chimpanzees. We share their excitement over this research, but for a different reason: Their data, together with our own data on children's early communication, put us on the brink of being able to situate the apes' communicative capacities vis a vis those of children. Their behaviors are similar to nonlinguistic gestures used by 9- to 16-month-old children. Kanzi's behavior raises important questions about haw he learns; we agree that his remarkable learning abilities distinguish him from other chimpanzees. The study also raises questions about what was learned, specifically how Kanzi's symbolic communication compares with the behavior of other language-trained apes and with that of children acquiring first languages. Here we disagree with many of Savage-Rumbaugh et al.'s (1986) conclusions. Kanzi's behavior differs from children's use oflanguage in systematic ways; positive comparisons to children can only be sustained by holding underspecified theories of and naming. We also disagree with their characterization of the extent to which Kanzi's communicative behavior differs from that of other language-trained apes. The similarities in the behaviors of several apes, including Kanzi, who have been exposed to very different experimental conditions suggest to us some basic generalizations about the