Research into non-human great ape language has involved teaching chimpanzees, bonobos, gorillas, and orangutans to communicate with human beings and with each other using sign language, physical tokens, and lexigrams; see Yerkish. Some primatologists argue that the primates' use of these tools indicates their ability to use "language", although this is not consistent with some definitions of that term.
Contents |
Animal language research attempts to answer the following questions:
Non-human animals have been recorded to have produced behaviors that are consistent with meanings accorded to human sentence productions. (A production is a stream of lexemes with semantic content. A language is grammar and a set of lexemes. A sentence, or statement, is a stream of lexemes that obeys a grammar, with a beginning and an end.) Some animals in the following species can be said to "understand" (receive), and some can "apply" (produce) consistent, appropriate, grammatical streams of communication. David Premack and Jacques Vauclair have cited language research for the following animals:
Sign language and computer keyboards are used in primate language research because non-human primate vocal cords cannot close fully,[11][12] and they have less control of the tongue and lower jaw.[13] However, primates do possess the manual dexterity required for keyboard operation.
Many researchers into animal language have presented the results of the studies described below as evidence of linguistic abilities in animals. Many of their conclusions have been disputed.[14][15]
It is now generally accepted that Apes can learn to sign and are able to communicate with humans. However, it is disputed as to whether they can form syntax to manipulate such signs.
Washoe, a Common Chimpanzee, was caught in the wild in 1966. When she was about ten months old, she was received by the husband-and-wife research team of Beatrix T. Gardner and R. Allen Gardner.[16] Chimpanzees are completely dependent until two years of age and semi-dependent until the age of four. Full adult growth is reached between 12 and 16 years of age. So the Gardners received her at a good age for research into language development. The Gardners tried to make Washoe's environment as similar as possible to what a human infant with deaf parents would experience. There was always a researcher or assistant in attendance during Washoe's waking hours. Every researcher communicated with Washoe by using American Sign Language (ASL), minimizing the use of the spoken voice. The researchers acted as friends and companions to Washoe, using various games to make the learning as exciting as possible.
The Gardners used many different training methods:
The results of the Gardners' efforts were as follows:
Linguistic critics challenged the animal trainers to demonstrate that Washoe was actually using language and not symbols. The null hypothesis was that the Gardners were using conditioning to teach the chimpanzee to use hand formations in certain contexts to create desirable outcomes, and that they had not learned the same linguistic rules that humans innately learn.
In response to this challenge, the chimpanzee Nim Chimpsky was taught to communicate using sign language in studies led by Herbert S. Terrace. In 44 months, Nim Chimpsky learned 125 signs.[17] However, linguistic analysis of Nim's communications demonstrated that Nim's use was symbolic, and lacked grammar, or rules, of the kind that humans use in communicating via language. This constitutes a chimpanzee vocabulary learning rate of roughly 0.1 words per day. This rate is not comparable to the average college-educated English-speaking human who learns roughly 14 words per day between ages 2 and 22.[18]
A two-year study by researchers from the University of St Andrews of chimpanzees at Budongo Conservation Field Station in Uganda, concluded that this wild group make use of at least 66 distinct gestures to facilitate communication.[19]
Sarah and two other chimpanzees, Elizabeth and Peony, in the research programs of David Premack, demonstrated the ability to produce grammatical streams of token selections. The selections came from a vocabulary of several dozen plastic tokens; it took each of the chimpanzees hundreds of trials to reliably associate a token with a referent, such as an apple or banana. The tokens were chosen to be completely different in appearance from the referents. After learning these protocols, Sarah was then able to associate other tokens with consistent behaviors, such as negation, name-of, and if-then. The plastic tokens were placed on a magnetic slate, within a rectangular frame in a line. The tokens had to be selected and placed in a consistent order (a grammar) in order for the trainers to reward the chimpanzees.
One other chimpanzee, Gussie, was trained along with Sarah but failed to learn a single word. Other chimpanzees in the projects were not trained in the use of the tokens. All nine of the chimpanzees could understand gestures, such as supplication when asking for food; similarly, all nine could point to indicate some object, a gesture which is not seen in the wild. The supplication is seen in the wild, as a form of communication with other chimpanzees.[20]
A juvenile Sumatran orangutan Aazk (named after the American Association of Zookeepers) who lived at the Roeding Park Zoo (Fresno, California) was taught by Gary L. Shapiro from 1973 to 1975 how to "read & write" with plastic children's letters, following the training techniques of David Premack. The technique of conditional discrimination was used such that the orangutan could eventually distinguish plastic letter (symbols) as representations of referents (e.g., object, actions) and "read" an increasingly longer series of symbols to obtain a referent (e.g., fruit) or "write" an increasingly longer series of symbols to request or describe a referent. While no claim of linguistic competence was made, Aazk's performance demonstrated design features of language, many similar to those demonstrated by Premack's chimpanzee, Sarah.
Kanzi, a Bonobo, is believed to understand more human language than any other nonhuman animal in the world. Kanzi apparently learned by eavesdropping on the keyboard lessons researcher Sue Savage-Rumbaugh was giving to her adoptive mother. Kanzi learned to communicate with a Lexigram board, pushing symbols that stand for words. The board is wired to a computer, so the word is then vocalized out loud by the computer. This helps Kanzi develop his vocabulary and enables him to communicate with researchers.
One day, Rumbaugh used the computer to say to Kanzi, "Can you make the dog bite the snake?" It is believed Kanzi had never heard this sentence before. In answering the question, Kanzi searched among the objects present until he found a toy dog and a toy snake, put the snake in the dog's mouth, and used his thumb and finger to close the dog's mouth over the snake. In 2001, Alexander Fiske-Harrison, writing in the Financial Times, observed that Kanzi was "asked by an invisible interrogator through head-phones (to avoid cueing) to identify 35 different items in 180 trials. His success rate was 93 per cent."[21] In further testing, beginning when he was 7 ½ years old, Kanzi was asked 416 complex questions, responding correctly over 74% of the time. Kanzi has been observed verbalizing a meaningful noun to his sister.[22]
Some scientists, including MIT linguist Noam Chomsky and cognitive scientist Steven Pinker, are skeptical about claims made for great ape language research.[23][24] Among the reasons for skepticism are the differences in ease with which human beings and apes can learn language; there are also questions of whether there is a clear beginning and end to the signed gestures and whether the apes actually understand language or are simply doing a clever trick for a reward.
While vocabulary words from American Sign Language are used to train the apes, native users of ASL note that mere knowledge of ASL's vocabulary does not equate to ASL, but more closely reflects Pidgin Signed English which is not a full-fledged language. In the research involving Washoe, all researchers returned lists of signs Washoe used, with the exception of the one deaf native ASL user who reported no signs but many gestures. Native users of ASL make clear distinctions about what handshapes, palm orientations, and places of articulation signs must have to constitute linguistic activity. Signs must also be used combinatorially and in the correct grammatical sequence. Thus, apes are seen as attempting to approximate these complex rules but are considered to be failing because of such malformations in the production of ASL signs. A precondition for a successful experiment with teaching a true sign language to primates ought to be ensuring that the main contact persons are all native speakers of the sign language, as it is otherwise analagous to trying to raise a human child as a speaker of a language to which you possess only a dictionary -- with mispronunciations and worst of all giving only a pidgin model.
Fantasy writer Edgar Rice Burroughs invented a fictitious great ape language called Mangani in his Tarzan books. This imagined language included such words as Kreegah! ("Beware!") and Tarmangani ("Great White Ape"). These words and others are sometimes used by cartoonists, and for facetious slang. (See Kreegah bundolo).
Writer Michael Crichton used the concept of great ape language in his 1980 novel Congo, in which a fictional gorilla named Amy communicates extensively with her keeper using ASL. This is also shown in the movie Congo.
The X-Files has an episode titled Fearful Symmetry in which a gorilla named Sophie communicates extensively with humans via sign language.
The 1987 film Project X, starring Matthew Broderick, had Chimpanzee use of American Sign Language as an important part of the plot.
The 2011 film Rise of the Planet of the Apes depicts apes using sign language to communicate with humans and with each other. Though the apes' brains have been enhanced in the film, there is an orangutan shown to use sign language prior to any enhancement.
|
||||||||||||||||
|
|||||||||||