General linguistic competency in the Deaf, a prerequisite for developing a theory of mind?

grantor: University of TorontoRecently it has been argued that the "standard" empirical tests of a theory of mind may be troubled by linguistic performance constraints (Freeman, Lewis, & Doherty, 1991). As a result, children may understand false beliefs but may be unable to demonstrate their capacities because of the methodologically imposed and computationally complex linguistic demands. This is particularly true for Deaf children whose linguistic competence is often limited. The purpose of this study, therefore, is to ascertain if language is constitutive of a developed theory of mind, by determining if Deaf participants display characteristics of a theory of mind even when tested with linguistically simple tasks. Two non-verbal tasks that were designed to measure characteristics of a theory of mind were administered to Deaf children 3 to 10 years of age. It was hypothesized that if human language is not necessary for a theory of mind, then Deaf children whose language is delayed but who otherwise are cognitively intact would perform as well as their age equivalent Hearing counterparts on such non-verbal tasks. If language competence is constitutive of a theory of mind, Deaf children's performance on such tasks would be impaired. Results from three experiments suggest that older Deaf children's ability to demonstrate characteristics indicative of a theory of mind is more closely associated with their general linguistic competence than their chronological age. As Deaf and Hearing children are otherwise cognitively similar (Martin, 1993; Rodda & Grove, 1987), the poor performance of linguistically limited Deaf children on these non-verbal tasks suggests that language proficiency is constitutive of a developed theory of mind.Ph.D