A Review of the Literature
By Karen Shaw
For Professor Dyer's Class
March 2, 2005
Over the past 30 years researchers have demonstrated that the great apes (chimpanzees gorillas and orangutans) resemble humans in language abilities more than had been thought possible. Just how far that resemblance extends however has been a matter of some controversy. Researchers agree that the apes have acquired fairly large vocabularies in American Sign Language and in artificial languages but they have drawn quite different conclusions in addressing the following questions: 1. How spontaneously have apes used language?
2. How creatively have apes used language?
3. Can apes create sentences?
4. What are the implications of the ape language studies?
This review of the literature on apes and language focuses on these four questions.
How Spontaneously Have Apes Used Language?
In an influential article Terrace, Petitto, Sanders, and Bever (1979) argued that the apes in language experiments were not using language spontaneously, but were merely imitating their trainers, responding to conscious or unconscious cues. Terrace and his colleagues at Columbia University had trained a chimpanzee, Nim, in American Sign Language, so their skepticism about the apes' abilities received much attention. In fact funding for ape language research was sharply reduced following publication of their 1979 article "Can an Ape Create a Sentence?" In retrospect the conclusions of Terrace et al. seem to have been premature. Although some early ape language studies had not been rigorously controlled to eliminate cuing even as early as the 1970s R. A. Gardner and B. T. Gardner were conducting double-blind experiments that prevented any possibility of cuing (Fouts, 1997, p. 99). Since 1979, researchers have diligently guarded against cuing. Perhaps the best evidence that apes are not merely responding to cues is that they have signed to one another spontaneously, without trainers present. Like many of the apes studied, gorillas Koko and Michael have been observed signing to one another (Patterson & Linden, 1981). At Central Washington University the baby chimpanzee Loulis placed in the care of the signing chimpanzee Washoe, mastered nearly fifty signs in American Sign Language without help from humans. "Interestingly," wrote researcher Fouts (1997), "Loulis did not pick up any of the seven signs that we [humans] used around him. He learned only from Washoe and [another chimp] Ally" (p. 244). The extent to which chimpanzees spontaneously use language may depend on their training. Terrace trained Nim using the behaviorist technique of operant conditioning, so it is not surprising that many of Nim's signs were cued. Many other researchers have used a conversational approach that parallels the process by which human children acquire language. In an experimental study, O'Sullivan and Yeager (1989) contrasted the two techniques, using Terrace's Nim as their subject. They found that Nim's use of language was significantly more spontaneous under conversational conditions.
How Creatively Have Apes Used Language?
There is considerable evidence that apes have invented creative names. One of the earliest and most controversial examples involved the Gardners' chimpanzee Washoe. Washoe, who knew signs for "water" and "bird," once signed "water bird" when in the presence of a swan. Terrace et al. (1979) suggested that there was "no basis for concluding that Washoe was characterizing the swan as a bird that inhabits water. '" Washoe may simply have been "identifying correctly a body of water and a bird, in that order" (p. 895).
Other examples are not so easily explained away. The bonobo Kanzi has requested particular films by combining symbols on a computer in a creative way. For instance, to ask for Quest for Fire, a film about early primates discovering fire, Kanzi began to use symbols for "campfire" and "TV" (Eckholm, 1985). The...