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Professor David Premack, currently at the University of Pennsylvania, and Ann James Premack, a science writer, began this program in 1964. Premack started his work at the Yerkes Laboratories of Primate Biology in Orange Park, Florida, a program at the University of Florida, continued it at the University of Missouri, then at the University of California, Santa Barbara, and currently at the University of Pennsylvania.
- "We now know that someone who comprehends speech must know language, even if he or she cannot produce it" (p. 13, Premack and Premack1).
The subjects of the program, nine chimpanzees, were reared in a laboratory environment which was specifically meant to stimulate their intellect by being complex and stimulating, as animals raised otherwise fail to thrive (for example, their appetites might otherwise decline). This was in contrast to the traditional psychology lab where the animals are caged and remain in solitude. The animals are:
- Sarah, born in 1962, demonstrated use of an invented language
- Gussie, failed to learn any words
- Elizabeth, trained in the language
- Peony, trained in the language
- Walnut, a late arrival, trained in the language, but failed to learn any words.
- Jessie, 1975 control, not trained in the language, but demonstrating pointing
- Sadie, 1975 control, not trained in the language, but demonstrating pointing
- Bert, 1975 control, not trained in the language, but demonstrating pointing
- Luvie, 1975 control, not trained in the language, but demonstrating pointing
Language suitable for an apeEdit
The language designed by Premack for an ape was not verbal; Premack's chimpanzee program differed from that of a separate research program in which other chimpanzees, were raised in a human family in parallel with human babies, and taught words3. Eventually, the chimpanzees might get to a two-year-old human's list of words, but no further. Vicki (chimpanzee) was eventually trained to speak four words3. The experiments on those chimpanzees did not demonstrate the existence of the faculties shown by Sarah (chimpanzee) discussed below, in her command of a language, for example. In other experiments, other chimpanzees have been taught American Sign Language, notably Washoe (chimpanzee)11.12 Washoe could use 68 gestures after three years of training, eventually getting to 150 gestures. However, Nim (chimpanzee)13, trained in American Sign Language, was found to demonstrate no forms with grammar, his linguistic productions being sets of gestures in no particular order. Koko (gorilla)14 and Chantek (orangutan)15 were also trained in American Sign Language. See also Kanzi's 200-word vocabulary of spontaneous productions as of 2005.
The language tokensEdit
The language consisted of a series of colored plastic tokens, which the chimpanzees could manipulate and stick to a magnetic board. Each token stood for a word which was never spoken in the chimpanzee's presence. Sarah began her language training in 1967 at age 5, beginning with food exchanges, in order to establish a social exchange with the instructor. The Premacks note that the chimpanzees gave food reluctantly and unwillingly, far preferring to receive food. In a series of experiments, Premack was able to train Sarah, Elizabeth, and Peony to parse sentences:
which might result in Peony touching the trainer's nose. The tokens did not resemble the objects; an apple was symbolized by a blue triangle token. The chimpanzee Elizabeth would be symbolized by a decorated E token, a copy of which would dangle from a necklace around her neck. The trainer would also wear a corresponding token, as would other investigators whom the chimpanzee would have to name in the formation of the target sentence. It took Sarah, Elizabeth, and Peony each hundreds of trials to first form an association between the tokens and the objects. Sarah in particular was trained in the token manipulations for eighteen months. Sarah was able to learn imperative sentences with a grammar,
- Sarah jam bread take
in which the trainer allowed her to take the bread and jam, and also negative sentences
- No Sarah honey cracker take
in which the trainer restrained her from taking the cracker and honey, which taught Sarah to suppress her impulse to take the negated object. In particular, the noun had to be at the beginning and the verb had to be at the end of the production, or else the trainer would not respond to Sarah's ungrammatical sentence. After hundreds of trials, Sarah could reliably produce the grammatical form
- Mary give apple Sarah
List of tokensEdit
- Colors (tokens were not colored with the corresponding colors)
Sarah was also able to answer questions in the form of a question token "?" which she could answer by selecting a resolving token. However Sarah was never able to ask questions by manipulating the "?" token. The question "What is the color of apple?"
- "?" color of apple (blue triangle)
would be answered with the token for 'red' (a gray curved token).
Premack was able to demonstrate that Sarah could understand how to decode a symbol stream after training. First she had to learn the token "name-of" and then learn that some new, but real objects had the name-of fig token1 and crackerjack token2.
- Real fig name-of fig token1
- Real crackerjack name-of crackerjack token2.
She was tested with
- fig token1 "?" Real crackerjack
which she answered correctly with
- fig token1 Not name-of Real crackerjack
Finally, with the trainer placing a ripe fig on the table, and the tokens fig token1, crackerjack token2, give, Mary, Sarah, orange, banana, Sarah produced the new sentence
- Mary give fig token1 Sarah
and with the trainer placing a crackerjack on the table, Sarah produced the new sentence
- Mary give crackerjack token2 Sarah
Sarah, Peony, and Elizabeth were able to respond to and formulate analogies and to express judgements. In these trials, problems were formulated by videotaped situations involving an actor, both friendly and unfriendly. With no training, and with observation of the laboratory only, Sarah was able to select answers requiring judgement, based on her experiences in the laboratory, such as the fact that a light cord had to be plugged in to solve some problems. Sarah was able to select proposed solutions for resolving the situations.
Sarah was most accurate on judgements of sameness, less so on similarity, and least accurate on judgements of difference. Human children were then tested with the same protocols, using speech. Young children passed the tests on number but failed on tests measuring conservation of liquid and solid. Five to six-year-old children passed the tests on conservation of liquid and solid, suggesting a similar process for the cognition of measurement of conservation of liquid and solid, between ape and human.
The Conditional statementEdit
Sarah was able to parse the following sentence in a way to give her the most reward:
- Sarah take banana if-then Mary no give chocolate
- (both an apple and a banana portion are presented for Sarah to take as part of the statement)
The chimpanzees do not spontaneously point outside of the psychological laboratory. The control chimpanzees, who were not trained in the language, could all point in order to communicate with the trainers.
Mappings and other representationsEdit
Washoe (chimpanzee)11,12 was able to spontaneously sign, in contrast to Nim (chimpanzee)13. Kanzi (bonobo)17, at age 30 months demonstrated spontaneous production of gestures and keyboard presses to ask for desired objects or events, and to name items in response to queries from the trainer. Kanzi previously played in the training room where his adoptive mother Matata (bonobo) was being trained with gestures and keyboard presses ("Lexigrams") 16. The spontaneous productions by Kanzi occurred in the absence of Matata. Kanzi can currently produce 200 words and recognize 500.
The Premacks note that chimpanzees use some gestures with each other, which the trainers use to communicate with both the language-trained chimpanzees and the control chimpanzees.
- Requests for food
- hand cupped, palm upward, for a chimpanzee to place food in.
- extruding lips in supplication
- One chimpanzee, trembling, hugged Premack at the beginning of his career, as if to appease him at the time of displaying outrage
Other personal traitsEdit
The Premacks stated that the chimpanzees had specific traits, such as favorite trainers, and that some chimpanzees, such as Gussie seemed more fearful than the others. As previously noted, The Premacks noticed that Jessie seemed to be the brightest of the nine chimpanzee subjects. For example, she did not hesitate to unmask a masked researcher, which none of the other chimpanzees attempted. It is clear that the Premacks attempted to provide a humane, supportive environment for the chimpanzees.
Vauclair notes that chimpanzees will become distressed in the absence of their favorite companion. (Vauclair p. 76)
- Note 1: David Premack and Ann James Premack (1983), The Mind of an Ape ISBN 0-393-01581-5 Norton. The Premacks have annotated a list of references which include:
- Note 2: W.N. Kellogg and L.A. Kellogg (1933), The Ape and the Child: a study of Environmental Influence Upon Early Behavior. New York: McGraw-Hill.
- Note 3: Catherine Hayes (1951), The Ape in Our House New York: Harper.
- Note 4: K.L. Hayes and C.H. Nissen (1971), "Higher Mental Functions of a Home-Raised Chimpanzee", in A.M. Schrier and F. Stollnitz (eds.) Behavior of Non-Human Primates. New York: Academic Press. pp. 60-114.
- Note 5: The Premacks list their selections for what they then considered to be the best references in ethology for the chimpanzee in the wild:
- Note 6: Jane Goodall (1971) In the Shadow of Man
- Note 7: V. Reynolds and F. Reynolds (1965) "Chimpanzees of the Bubongo forest" in I. Devore (ed.) Primate Behavior:Field studies of monkeys and apes. New York: Holt, Rinehart and Winston
- Note 8: F.X. Plooij (1978) "Some basic traits of language in wild chimpanzees?" in A. Lock (ed.) Action, Gesture and Symbol New York: Academic Press.
- Note 9: T. Nishida (1968) "The social group of wild chimpanzees in the Mahali Mountains". Primates 9, 167-224
- Note 10: In addition to citing Premack, more references are cited by Jacques Vauclair (1996) Animal Cognition: an introduction to Modern Comparative Psychology ISBN 0-674-03703-0:
- Note 11: R.A. Gardner and B.T. Gardner (1969), "Teaching Sign Language to a Chimpanzee", Science 165, 664-672.
- Note 12: R.A. Gardner, B.T. Gardner and T.E. Van Cantfort (1989), Teaching Sign Language to Chimpanzees, Albany: SUNY Press.
- Note 13: H.S. Terrace (1979). Nim: A chimpanzee who learned Sign Language New York: Knopf.
- Note 14: F.G. Patterson and E. Linden (1981), The education of Koko, New York: Holt, Rinehart and Winston
- Note 15: H.L. Miles (1990) "The cognitive foundations for reference in a signing orangutan" in S.T. Parker and K.R. Gibson (eds.) "Language" and intelligence in monkeys and apes: Comparative Developmental Perspectives. Cambridge Univ. Press. pp.511-539
- Note 16: E.S. Savage-Rumbaugh, K. McDonald, R.A. Sevcik, W.D. Hopkins, and E. Rupert (1986). "Spontaneous symbol acquisition and communicative use by pygmy chimpanzees (Pan paniscus)". Journal of Experimental Psychology:General 115, 211-235.
- Note 17: E.S. Savage-Rumbaugh, D.M. Rumbaugh, K. McDonald (1985). "Language learning in two species of apes". Neuroscience and Biobehavioral Reviews 9, 653-665.
- Note 18: R.J. Schusterman and R. Gisiner, "Artificial language comprehension in dolphins and sea lions: The Essential Cognitive Skills". The Psychological Record, 38, 311-348.
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