Three chimpanzees learned to label three edibles as "foods" and three inedibles as "tools". Two chimpanzees could then similarly categorize numerous objects during blind trial 1 tests when shown only objects' names. The language-like skills of the chimpanzee who failed (Lana) illustrates that apes can use symbols in ways that emulate human usage without comprehending their representational function.

The field of ape language has been in turmoil since the publication of Terrace's (1979) work with. Nim, a chimpanzee. Terrace's findings regarding the linguistic competencies of apes contrasted sharply with those put forth earlier by Gardner and Gardner (1971). We discuss these and other ape-language projects and contrast the preverbal communicative skills of chimpanzees with those of human children in order to, determine the cognitive competencies that chimpanzees bring to the task of language acquisition. We conclude that children enter the one-word stage with a gestural-referential complex of abilities that permits them to engage quickly in a process of mutual vocal reference and that predisposes them to view words as behaviors that stand for or replace objects. Chimpanzees do not seem to develop spontaneously a similar gestural-referential complex of communicative skills, and therefore they do not readily comprehend the act of reference that the teacher is engaged in while pointing to and naming objects. Thus, although chimpanzees imitate the symbol, they do not readily interpret the symbol as a referent in the manner that a human child does. This distinction between child and chimpanzee has not been made previously, and it is suggested that the lack of such a distinction has resulted in overinterpretations of apes' linguistic abilities. Data are presented that demonstrate that the gestural-referential complex can be developed, with training, in the chimpanzee and that, consequently, naming with reference does appear. This is demonstrated in controlled tests with two chimpanzees. A review of the training that preceded the emergence of referential function in these chimpanzees suggests that symbolization is not a unitary skill but rather a combination of diverse productive and receptive skills. This view is supported by human data. Contrasting Views of Indication in Apesdifference between the use of language by apes ", , _ , , and children lies in the fact that apes do not Terrace and Rumbaugh seem motivated to use their words in any sort Terrace, Pettito, Sanders, and Bever (1979) of declarative or indicative sense. That is, they have asserted that a profound and important do not typically use symbols to announce to others what they are about to do or to draw the attention of others to objects or events.