Page 73 - Encyclopedia of Philosophy of Language

At the age of about 18 months, although Mulika could use only seven or eight lexigrams with competence, tests revealed that she understood 70 others!
2.2 Interspecies Comparisons
Was the ability to comprehend spoken English a par- ticular characteristic of bonobos or, given rearing from birth in a language-saturated environment, would the common chimpanzee exhibit similar com- petency? An answer to this important question was sought in a study that involved corearing the two species of Pan, P. paniscus and P. troglodytes, so as to give them the same early exposure to spoken English and social communicative use of the lexigram keyboard. The two subjects selected were Panbanisha, a bonobo, and Panzee, a common chimpanzee. Their ages differed by only six weeks at the beginning of the study. From shortly after their births, for the next four years these two chimpanzees were uniformly provided with an enriched environment that emphasized com- munication as did Kanzi's.
The experimenters expected that, under the con- ditions of their rearing that lacked all formal training, only the bonobo would come to comprehend English and use the keyboard. Initial results, up until the sub-
jects were about two years old, supported that expec- tation. Notwithstanding, the common chimpanzee also evidenced significant, though lesser competence in both speech comprehension and in the spontaneous learning of the lexigrams and their meanings. She understood words and used her keyboard to com- municate, thus revealing that environment was the critical ingredient in the spontaneous emergence of language skills in the chimpanzee as well as in the bonobo. On the other hand, the bonobo infant, Pan- banisha, was substantially ahead of the common chimpanzee infant, Panzee, in all criteria. This obser- vation, coupled with the extraordinarily limited speech comprehension skills of our four other com- mon chimpanzees, discussed above, strongly suggests that the bonobo has a unique proclivity for benefiting in language acquisition if reared from birth in a language-saturated environment.
3. Important Factors in Language Acquisition—What Can be Concluded from these Studies?
Kanzi, Mulika, Panbanisha, and Panzee learned language without the typical trial-based learning para- digm involving reward-based contingencies. Given the appropriate environment from shortly after birth and continuing for several years, an ape can acquire linguistic skills without contingent reinforcement in formal trial-by-trial training. (All other apes before them—Sherman, Austin, and Lana—required formal training designed to cultivate various language func- tions.) Normal human children do not require formal training to learn language. Most certainly, the fact that most children experience a communicative
environment from the moment they are born is critical to the acquisition of language.
Research with apes supports the view that a sen- sitive period exists for language acquisition (Green- ough, et al. 1987): exposure to language during this period is necessary for the activation and further development of cognitive structures supported by specific brain circuitry. Kanzi's mother, Matata, was an adolescent when first given language training, training from which she could not significantly benefit. Her language competence was negligible when com- pared to that of Kanzi and Panbanisha's who were given very rich language environments within which to develop from shortly after birth. Similarly, Lana, Sherman, and Austin were between 18 months and two years old when their language training began. They were, by comparison, minimally able to com- prehend human speech or to learn the meanings of lexigrams spontaneously. These observations suggest that it is during the first few months of life that ex- posure to language, including speech, is important if the continued development of language is to be optimal.
Germane to the support of this point are obser- vations on Tamuli, another bonobo; at the age of three years she was given the same experiences as Kanzi and Panbanisha's for seven months to see if she could acquire a vocabulary of lexigramsand come to comprehend spoken English. Tamuli failed to benefit other than minimally from that experience. Her lack of progress is consistent with the view that it is early within the first year of life that the sensitivetime occurs for exposure to language to impact optimally upon brain and cognitive structures. The competence for language is laid postnatally, if not prenatally, and during early infancy—not in the school's classroom.
If exposure to language is sufficiently early, no train- ing is needed for chimpanzees and bonobos to begin to understand speech and that symbols represent things and ideas. They will spontaneously begin to communicate under these conditions if provided with a keyboard. If exposure to language occurs after infancy, once the apes have already reached the juv- enile period, language skills can be inculcated through training but they do not appear spontaneously. In addition, even with training, the speech comprehen- sion skills of such apes remain extremely limited.
If exposure to language occurs at adolescence or later, even training appears to be insufficient to incul- cate functional, representational language skills in the ape. Of course, better training techniques could be discovered in the future which would make it possible even for these apes to learn language.
In humans, and now in apes as well, languageacqui- sition entails, first, comprehension. Comprehension develops long before the speech musculature has matured enough for vocal control permitting language production in the child (Golinkoff, et al. 1987).
It is now known that human children, raised from birth with the keyboards, use the lexigrams both to
Apes and Language
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