Theory of mind "beliefs", developmental characteristics and social understanding in children and adolescents with intellectual disabilities.

Patterns of development of ToM belief abilities in intellectually disabled (ID) children and typically developing (TD) children matched on their developmental age were investigated. The links between cognition, language, social understanding and ToM belief abilities were examined. EDEI-R [Perron-Borelli M. (1996). Echelles Différentielles d'Efficiences Intellectuelles. Forme Révisée (EDEI-R). Paris: Editions et Applications Psychologiques.] was used to match participants and to assess social understanding. ECOSSE [Lecocq P. (1996). L'E.CO.S.SE. Une épreuve de compréhension syntaxico-sémantique. Paris: Presses Universitaires du Septentrion.] assessed the level of syntactic and semantic comprehension of French speaking, to ensure a good comprehension of the questions in false belief tasks. Five tasks assessed the ability in visual perspective taking and in understanding of false belief. A difference in the global ToM ability was found between both groups (difference hypothesis in ID participants). Specific abilities in different ToM tasks showed developmental patterns partially different and partially similar, between ID and TD groups. The interest to assess the understanding of belief by means of several tasks is confirmed. Positive links between cognition, language and ToM abilities were found in both groups, but the impact of cognition and language on abilities in each ToM task is different in both groups. Finally, the specific impact of social understanding and of chronological age on abilities in false belief in ID group is discussed.