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Recent findings upon the area in monkeys homologous to the human Broca's area have radically changed our understanding of its underlying neurobiology. In particular, it puts the issue of the links between vocal imiation (the transformation of speech sounds into speech motor commands), and the nature, learning and evolution of speech hot on the agenda of issues in speech science. Last week, I reviewed the issues involved and proposed a new 'motor theory of speech' that takes accounts of recent neuroscience findings in the commentary ejournal Noetica. http://psy.uq.edu.au/CogPsych/Noetica/OpenForumIssue9/ Here is its abstract: Mirror Neurons and the motor theory of speech. Dr. John R. Skoyles skoylesMail to author|Respond to list|Read more issues|LINGUIST home page|Top of issueglobalnet.co.uk http://www.users.globalnet.co.uk/~skoyles/index.htm Mirror (imitation) neurons have recently been discovered in the homologous area to the Broca area in monkeys (Rizzolatti, Fadiga, Gallese & Fogassi, 1996; Rizzolatti & Arbib, in press; Gallese, Fadiga, Fogassi & Rizzolatti, 1996). How might the existence and evolution of speech link to them? Here I argue that informationally the one unique feature of human speech is that it is a vocabulary-based communication. As such, its existence requires that human infants can directly learn from overheard speech thousands of words in a short time by direct imitation. Cognitively, how infants vocally imitate overhead words is unexplained. In a revised motor theory of speech I tackle this problem. The motor theory of speech arose to explain why speech (in the form of phones) is characterised by motor articulation information. Originally, it did so in terms of enabling vocal mimicry and word perception (Liberman, 1957, p. 122). Subsequently, the imitation role was dropped; I restore it. Speech, I suggest, contains motor information so that infants can quickly imitate all its thousands of words merely from hearing them. Vocal imitability is created by a cognitive trick involving speech motor goals: these goals are always innate high-level auditory processing categorial invariants (innate and processed in the Wernicke's area). Because they are innate, these goals are easily extracted by infants from speech. This allows an infant's motor system to duplicate them and so duplicate vocalisations. This gaol duplication occurs in imitation circuits (using mirror neurons in the Broca's area).
To: Linguist List From: Bernard Comrie Date: 5 May 98 Subj: Twins' language (cryptophasia) The following correction, from Peter Bakker (linpbMail to author|Respond to list|Read more issues|LINGUIST home page|Top of issuehum.aau.dk), should be made to my posting on this subject (9/469, March 26): On Linguist List 9/469 (March 26) Bernard Comrie listed a number of titles relating to twins' private languages (cryptophasia) and summarized his findings as follows: "twin languages are not particularly autonomous; their apparent autonomy reflects rather greater distortion than normal of the language(s) of the twins' environment". While that is certainly true for the phonology and the lexicon (at least 90 percent of the vocabulary of each language can be traced back to the language of the environment), this is not true for the grammatical system. The grammatical systems do show a number of striking differences from the languages of the environment, and they also appear to have a number of structural features in common. I have discussed some of this in the 1987 and 1990 papers quoted in the list mentioned above. - Bernard Comrie Dept of Linguistics GFS-301 tel +1 213 740 3674 University of Southern California fax +1 213 740 9306 Los Angeles, CA 90089-1693, USA e-mail comrie
bcf.usc.edu Permanent address from 12 May 1998 Max Planck Institute for Evolutionary Anthropology Inselstrasse 22-26 D-04103 Leipzig, Germany Fax +49 341 96 17 537