Theory of mind and rule use in individuals with Down's syndrome: a test of the uniqueness and specificity claims.

The relationship between Theory of Mind (ToM) and rule use was explored in adults with Down's Syndrome (DS) and in non-handicapped pre-schoolers. Twelve low-functioning individuals with DS (mean mental age = 5.1 years, mean chronological age = 22.7) performed worse than 12 MA-matched non-handicapped children (mean MA = 5.1 years) on several standard ToM tasks and on a color-shape card-sorting task in which subjects were required to switch between two incompatible sets of rules. On the ToM tasks, people with DS tended to focus on a single state of affairs (e.g. the present situation). Likewise, on the card sort, these subjects tended to use a single set of rules on all trials. Performance in the two types of task was positively correlated when MA was partialed out. The results are inconsistent with the slaim that ToM reflects a domain-specific psychological function and the notion that deficits in ToM are unique to individuals with autism.