executive functions in students with high functioning autism and educable down syndrome

background and objective: the present study investigated executive functions in students with high functioning autism (hfa) and students with educable down syndrome (ds) with normal healthy students.     methods: fifteen boy students with hfa, 15 boy students with educable intellectual disability and 15 normal healthy boy students (aged between¬ 7-15 years) were recruited from educational services. the study samples were controlled and matched based on their demographic criteria. the utilized research instruments were the 2nd version of gilliam autism rating scale (gars2), wechsler intelligence scale for children (wisc) and its digit span subscale (direct and reverse) memory test, color-word stroop test, wisconsin card sorting test (wcst) and continuous performance test (cpt). to analyze the data, one-way anova, multivariate analysis of variances, univariate covariate, multivariate covariate and bonferroni and tukey post-hoc tests were used.     results: analysis of covariance showed that there was significant difference only between students with hfa and control groups in the response inhibition, mental flexibility index and continuous attention. moreover, there was significant difference between students with down syndrome and control group in short- term memory, while comparisons between other variables revealed no significant difference between groups.     conclusion: the results indicated that students with hfa considering their close iq to normal students showed impairment in the executive functioning. this finding implicates the minor role of intelligence in the executive function level in these children.