Language Research with Chimpanzees
Linguistic Research on Great Apes in the Twentieth Century
Feb 27, 2009
A number of researchers have studied if and how great apes can learn a human language system. Most of the research has been carried out with chimpanzees but since these animals do not have a physical vocal apparatus like humans, they can’t produce human language sounds – even if they can understand them. Instead of teaching chimpanzees to respond with sounds, researchers often teach them variations of sign language. Below are results from some well-known long-term studies on chimpanzees named Gua, Viki, Washoe, and Sarah.
Chimpanzee Gua
Gua was an infant chimpanzee who was raised with a human infant during the 1930s. The purpose of the study was to determine whether a chimpanzee could learn a human language if s/he was raised in a human home (Fromkin 1993, p. 426). At sixteen months, Gua was given a comprehension test. It was found that he understood about one hundred words, a number of verbal commands, some salutations, and a few instructions (Premack 1976, p. 28).
Chimpanzee Viki
Viki, like Gua, was raised in a human home; however, the purpose of this study was to determine if chimpanzees could learn to articulate. After a number of years, she was able to articulate only three words, and these took great effort, “mama”, “papa”, and “cup” (Premack 1976, p. 30). Viki was also tested for “higher mental functions” and it was revealed that she performed as well as a 3 ½ year old human child on number matching tasks. Further testing showed that she could distinguish between animate and inanimate objects in photographs, between male and female, and could sort items into categories.
Chimpanzee Washoe
Researchers began to realize that the approach to teaching language to apes must improve in order to compensate for apes’ physical inability to articulate human speech sounds. One method was to teach American Sign Language to the primates (ASL). Washoe was one of a number of chimpanzees who were trained in ASL and became the first nonhuman primate to learn human language. She was raised in an environment where she was surrounded constantly by signers and by the time she was four years old, she was able to sign 85 words and produce 2-word combinations (Fromkin 1993, p. 426).
Chimpanzee Sarah
Sarah was a chimpanzee who was taught an artificial language made up of symbols that were each a unique shape and colour, constructed of plastic, and backed with a piece of metal that adhered to a magnetic board (Premack 1976, p. 77). She “talked” by placing the symbols on the board in vertical sequences. A drawback to the study, however, was that she was not given the opportunity to produce spontaneous speech (Fromkin 1993, p. 427).
While the studies described above, as well as others, indicate that apes have some capacity to learn one – two hundred words, to respond to commands, and to produce 2-word utterances, the studies do not provide a reliable measure of how large that capacity is. Furthermore, the studies give no indication of syntactic ability among the apes, nor of the frequency of spontaneous speech production. Chimpanzees have, however, been shown to possess at least a child-like ability for conceptual distinctions, which have been put forth as a prerequisite to language development.
References
Fromkin, V. & Rodman, R. (1993). An Introduction to Language, 5th Ed. Fort Worth: Harcourt Brace Jovanovich College Publishers.
Premack, A.J. (1976). Why Chimps Can Read. New York: Harper & Row.
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