Role of Age, Siblings Verbal and Nonverbal Ability in Development of the Theory of Mind in Intellectually Disabled Students

Background: The purpose of this study is to investigate theory of mind development (TOM) with regard to mental retarded students (MRS) and its relationship with verbal and non-verbal abilities, and number of siblings. Materials and Methods: This study is a cross-sectional, for all male mental retarded students, age of 8 to 14 years (about 59 individuals) which were from the city Torbat-e Heidarieh, Iran. Unexpected-content task (UCT) and 38-items test were used for measuring TOM. Also, the Wechsler Intelligence Scale for children Revised (WISC-R) was used to examine the verbal and non-verbal abilities. Information of siblings was established in an interview with the parents, also by looking at the students’ ID cards. In order to analyze data, ANOVA, Scheffe, Pearson correlation coefficient and chi- square were carried out. Results: First and second level theory of mind development with regard to intellectually disable students were ascending to 12 years age (p < 0.05) and then maintained stable (p=0.87). However, theory of mind development that measured by Unexpected Content Task (UCT), was always ascending (p < 0.05). The verbal ability had a positive and significant correlation with first (p < 0.001) and second level (p < 0.001) theory of mind, while non-verbal ability had a positive and significant correlation with both first (p < 0.009) and second level (p < 0.001). Number of siblings had not been significantly correlated with theory of mind development which related to intellectually disable students (p > 0.05). Conclusion: Altogether, the things “theory theory” and “modular” approaches state might be acceptable. Those theories which are based on sociocultural approaches expressing experiment of communication underlies mind understanding development must be more examined.