Domain specificity in conceptual development 227

Leslie, A.M., and Thaiss, L., 1992. Domain specificity in conceptual development: Neuropsychological evidence from autism. Cognition, 43: 225–251. To understand some aspects of conceptual development it is necessary to take cognitive architecture into account. For this purpose, the study of normal development is often not sufficient. Fortunately, one can also study neurodevelopmental disorders. For example, autistic children have severe difficulties developing certain kinds of concepts but not others. We find that whereas autistic children perform very poorly on tests of the concept, believes, they are at or near ceiling on comparable tasks that test understanding of pictorial representation. A similar pattern was found in a second study which looked at understanding of a false map or diagram: normal 4-year-olds showed a marked advantage in understanding a Correspondence to: Alan M. Leslie, MRC Cognitive Development Unit, University of London, 17 Gordon Street, London WC1H OAH, UK *Parts of this work were presented in talks by the first author to the VIIIth European Workshop on Cognitive Neuropsychology, Bressanone, Italy, January 1990, to the Department of Psychology, University of Chicago, June 1990, and to the Conference on Cultural Knowledge and Domain Specificity, University of Michigan, Ann Arbor, October 1990. Our thanks to Daniel Roth, Simon BaronCohen, John Morton and Uta Frith for comments on an earlier draft, and to Jon Bartrip for help with data analysis. We are also grateful to the children and staff of Doucecroft School, Harborough School and Whitefield School for their assistance in these studies. Editor: This article should have appeared in Cognition volume 40, number 3, together with the article by Leekam & Perner entitled “Does the autistic child have a metarepresentational deficit?”. Unfortunately, an administrative error made this impossible and delayed the appearance of the present article. We apologize for this mistake. 0010-0277/92/$8.60 © 1992 – Elsevier Science Publishers B.V. All rights reserved. 226 A.M. Leslie and L. Thaiss false belief over a false map, while the autistic subjects performed better on the map. These findings suggest that the concept, believes, develops as a domain-specific notion that is not equatable with “having a picture (map or diagram) in the head”. This result supports the existence of a specialized cognitive mechanism, which subserves the development of folk psychological notions, and which is dissociably damaged in autism. We extend these ideas to outline a new model of the development of false belief performance.