Research into 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 these primates' use of the communication tools indicates their ability to use "language", although this is not consistent with some definitions of that term.
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- 1 Questions in animal language research
- 2 Non-human apes that demonstrate understanding
- 3 Primate use of sign language
- 4 Plastic tokens
- 5 Limitations of ape language
- 6 Criticisms of primate language research
- 7 See also
- 8 Notes
- 9 References
- 10 External links
Questions in animal language research
Animal language research attempts to answer the following questions:
- What problems can non-human animals solve without language, and can they solve them better after they have received language training?
- Can the lessons learned in teaching non-human animals be applied to human children?
- How, and how much, do non-human animals' abilities to learn language differ from those of humans?
- Are the abilities that underlie language general or highly specialized?
- Where is the line between language and other forms of communication?
Non-human apes that demonstrate understanding
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 (but see "Criticisms of primate language research", below):
Primate use of sign language
Sign language and computer keyboards are used in primate language research because non-human primate vocal cords cannot close fully, and they have less control of the tongue and lower jaw. However, primates do possess the manual dexterity required for keyboard operation.
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. 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. Accordingly, the Gardners received her at an appropriate 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:
- Imitation: After Washoe had learned a couple of words, she started, like chimpanzees usually do, to imitate naturally. For example, when she entered the Gardners' bathroom, she spontaneously made the sign for "toothbrush", simply because she saw one.
- Babbling: In this case, "babbling" does not mean vocal babbling. Instead, Washoe used untaught signs to express a desire. She used a begging gesture, which was not much different from the ASL signs "give me" and "come." (Human infants who are learning sign language often babble with their hands.)
- Instrumental Conditioning: The researchers used instrumental conditioning strategies with Washoe. For example, they taught the word "more" by using tickling as a reward. This technique was later applied to a variety of relevant situations.
The results of the Gardners' efforts were as follows:
- Vocabulary: When a sign was reported by three independent observers, it was added to a checklist. The sign had to occur in an appropriate context and without prompting. The checklist was used to record the frequency of a sign. A sign had to be used at least once a day for 15 consecutive days before it was deemed to have been acquired. Alternatively, a sign had to be used at least 15 days out of 30 consecutive days. By the end of the 22nd month of the project, thirty-four signs had been learned.
- Differentiation: Washoe used the sign "more" in many different situations until a more specific sign had been learned. At one point, she used the sign for "flower" to express the idea of "smell." After additional training, Washoe was eventually able to differentiate between "smell" and "flower."
- Transfer: Although the same object was presented for each learning trial (a specific hat, for example), Washoe was able to use the sign for other similar objects (e.g. other hats).
- Combinations: Washoe was able to combine two or three signs in an original way. For example, "open food drink" meant "open the fridge" and "please open hurry" meant "please open it quickly."
Washoe also taught other chimpanzees, such as Loulis, some ASL signs without any help from humans.
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 (whose name is a play on linguist Noam Chomsky) was taught to communicate using sign language in studies led by Herbert S. Terrace. In 44 months, Nim Chimpsky learned 125 signs. 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.
Dr. Francine "Penny" Patterson, a student of the Gardners, in 1972 began an ongoing program to teach ASL to a lowlands gorilla. Unlike the Gardners she did not limit her English speech around Koko, and as a result Koko understands approximately 1,000 ASL signs and 2,000 English words. Her results were similar to the Gardners' results with chimpanzees; although the gorilla learned a large number of signs she never understood grammar or symbolic speech, and hasn't displayed any cognition beyond that of a 2-3 year old human child.
Gestural communication in the wild
In the first long-term study of gestural communication in the wild, researchers from the University of St Andrews, working at the Budongo Conservation Field Station in Uganda, found a large repertoire of at least 66 different gestures (including bodily movements), which included almost all types of gesture reported in studies from other chimpanzee sites both in captivity and the wild. This led them to argue that the repertoire of available gesture types that can be employed in natural chimpanzee gestural communication is species-typical. In a parallel study at the same site, researchers from Stirling found 30 different manual gesture types in mature chimpanzees; many of which appear similar to human manual gestures such as arm beckon, point, clap and flail. The first systematic quantitative comparison of gestural signaling of two different chimpanzee subspecies (Pan troglodytes schweinfurthii; Pan troglodytes versus) and communities (Taï South Group, Taï National Park, Ivory Coast; Kanyawara, Kibale National Park, Uganda) however showed that dyads and groups differ in their gestural performance and usage, with gestures and their meaning being acquired via social negotiation with conspecifics. 
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.
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 his 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." 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.
Limitations of ape language
Despite their impressive (although still sometimes disputed) achievements, Kanzi and other apes, who participated in similar experiments, failed to ask questions themselves. Joseph Jordania suggested that the ability to ask questions is probably the central cognitive element that distinguishes human and animal cognitive abilities. (However, a parrot named Alex was apparently able to ask simple questions. He asked what color he was, and learned "grey" after being told the answer six times.) Enculturated apes, who underwent extensive language training programs, successfully learned to answer quite complex questions and requests (including question words "who", "what", "where"), although so far they failed to learn how to ask questions themselves. For example, David and Anne Premack wrote: "Though she [Sarah] understood the question, she did not herself ask any questions – unlike the child who asks interminable questions, such as What that? Who making noise? When Daddy come home? Me go Granny's house? Where puppy? Sarah never delayed the departure of her trainer after her lessons by asking where the trainer was going, when she was returning, or anything else". The ability to ask questions is sometimes assessed in relation to comprehension of syntactic structures. Jordania suggested that this approach is not justified, as (1) questioning is primarily a cognitive ability, and (2) questions can be asked without the use of syntactic structures (with the use of specific intonation only). It is widely accepted that the first questions are asked by humans during their early infancy, at the pre-syntactic, one word stage of language development, with the use of question intonation.
Criticisms of primate language research
Some scientists, including MIT linguist Noam Chomsky and cognitive scientist Steven Pinker, are skeptical about claims made for great ape language research. 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.
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