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herbert_terrace.jpgThe keynote lecture at this Winter Conference on Animal Learning and Behavior was presented by Herb Terrace who started a research project on the chimpanzee Nim Chimpsky in 1972. You can watch the HBO/BBC documentary on Project Nim, which focuses on the ethical issues and the narrative story of Nim's life. Nim's name is a pun on eminent linguist Noam Chomsky, who criticized the book "Verbal Behavior" of Terrace's thesis advisor BF Skinner in a scathing review. Skinner had claimed that language was acquired through a process of operant conditioning, while Chomsky found that the parallels between operant conditioning and language acquisition were 'trivial' at best and instead claimed that humans possess inborn language acquisition devices, that only need ot be exposed to language for language to form.

Not all that unexpectedly if you have seen the movie, Herb started out by stating very explicitly that he thought the movie 'Project Nim' was a bad misrepresentation of the actual events. He said that director Peter Marsh not only didn't understand the scientific method and hence the project, but that he also made it look as if some fundamental animal rights had been violated, when the animal rights movement didn't even start before 1976.

More to the scientific topic of this session, he posed the question: "did language evolve?" He said that chimpanzees are not necessarily the best models to study the evolution of language in, only because they're our closest ancestors. He cited Chomsky saying that language didn't evolve, but rather suddenly arrived as a by-product of the enlargement of the human brain. Moreover, Chomsky wrote that there is no substance to the assertion that language evolved (which would be laughable if it hadn't been Chomsky who wrote it). No other species besides humans have language, which is puzzling, because one only very rarely sees a biological adaptation confined to only one species. In order to elaborate this further, Herb went over the evolution of brain size in the primate/hominin lineage and how the concomitant decrease in the diameter of the female birth canal.

He went on to cover Vervet Monkey alarm calls and the honey bee dance communication as examples for inborn communication systems. Unlike a bee, chimpanzees look at a human and we get the impression that it is 'almost there': we empathize with them and can't help the impression that we should be able to communicate. Thus, the early Chimpanzee projects aimed at teaching chimpanzees signs in the hope that grammatical use of these signs would appear. The first ape language project was a chimpanzee called 'Sarah' who used different objects as symbols for objects and verbs such as 'give' or 'get' and nothing in these symbols would be connected to the meaning of the symbols. A similar project involved 'Lana'. About at the same time (~1967) came projects using American sign language, based on Skinner's proposition that langugae is based on an operant process. The first of these projects involved 'Washoe", then Kanzi, a bonobo and Koko the gorilla. While Sarah and Lana used sign sequences such as "Mary give Sarah apple", Washoe was the first ape to use American sign language. He was reported to have said 'water Bird' to refer to a swan, or 'more water', 'more tickle'. The question to Herb at that time became: how reliable are these combinations? What were the frequencies of water bird vs. bird water? Answering these questions required a corpus, a collection of all of the chimpanzee's utterances. This was the scientific backdrop of project Nim.

Nim produced sign sequences like 'Nim hug cat'. Herb showed tables for 2, 3 and 4 word combinations and how often they occurred. It appeared as if many of the 4-word combinations didn't make much sense and contained many repetitions. Nim's longest utterance consisted of 16 words and Herb speculated that hes combinations become longer because his trainers would hold off the reward expecting Nim to go on and so Nim kept repeating signs in order to finally get he reward. Herb went on to show several data sets showing how the word usage of Nim was drastically different from that of deaf children using the same sign language. These data showed to me that project Nim was not a failure, as the movie implied, but it taught us something about chimpanzee behavior. Nim's usage of signs was exclusively used as requests and as such his sequences of signs were merely sophisticated begging devices.

Nim didn't learn language, but he was certainly not what Descartes would have called a 'thoughtless automaton' that behaved solely on Stimulus A eliciting a Response A. How do you show that an animal 'thinks'? 'Delayed matching to sample' experiments constitute a challenge for simple associative explanations of animal behavior. Another experiment is to use sequence learning, in which the animals learn lists of images in a fixed order. For instance, the animals were trained on four different lists of four different images. By presenting them one image of each of the different lists, it could be shown that monkeys remembered not only the lists, but also the ordinal position of each item in each list. I guess what he wanted to say was that there is a lot of 'thinking' going on in a monkeys brain that is difficult to explain with the behaviorist explanations of his thesis advisor Skinner.

In the final part of his lecture, Herb described the development of a white sclera in humans, allowing us to more precisely judge where someone else is looking. Paralleling this difference is an increased frequency and duration of eye-to-eye contact between child and mother in humans compared to non-human primates. Herb argues that this eye contact between mother and infant is where 'theory of mind' begins, as the infant learns to distinguish between 'me' and 'Mommy'. More behaviors are playing peek-a-boo, gaze-following or pointing. The general message, I guess, that Herb was trying to get across here was that chimpanzees do not have a theory of mind.

Clearly, Herb Terrace is not the kind of reckless, incompetent researcher the movie portrait him as. I enjoyed the lecture and learned quite a bit from it. I'm looking forward to the remainder of the session where two more talks will go into theory of mind and then I'll talk about flies
Posted on Monday 30 January 2012 - 01:54:21 comment: 0

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