Objective: The purpose of this study was to investigate development of the theory of mind (TOM) of mentally retarded students and its relationship with the number of siblings.
Materials & Methods: This descriptive study was in correlation determination type, the total number of 8-14 years old mentally retarded students (59 people) who were studying in 1st to 5th degree of primary school in Mee’aad education center of Torbat-e Heidarieh (the only male education center of Torbat-e Heidarieh) in academic year 2008-09 participated. To collect data of theory of mind (TOM) Unexpected-content task and 38-item test of theory of mind were used. In order to analyze data, ANOVA, Scheffe, Pearson correlation coefficient and Chi- square were carried out.
Results: The first and second level of the evolution theory of mind of the mentally retarded students ascending to 12 years (P<0.001) and then fixed (P=0.87). But that theory of mind development which was measured by Unexpected-content task, was ascending (P=0.02). Also, the number of siblings was not statistically significantly correlated with theory of mind development of mentally retarded students (P=0.52).
Conclusion: Theory of mind development of mental retarded students varies based on that type of task being used to assess. In total, the claim of Theory-Theory approach, that says theory of mind development is on the basis of necessary processes, could be accepted. Also those theories which are based on cultural-social approaches calming that experience with other people causes development of mind understanding need to be more examined.