Estimating Receptive Core Vocabulary in Preschoolers with Intellectual Disability in Tehran

This article aims at estimating core vocabulary of preschoolers with intellectual disability in Tehran. Stratified matrix sampling was used for choosing and grouping the 90 informants. Three groups (each group 16 boys and 14 girls) were selected among the preschoolers less than 9 years. Based on Nematzadeh et.al (2005) two subtests were modified and developed: Perceptive and Lexical factors which assessed understanding of 694 and 830 words have been respectively evaluated. 14 informants were chosen for filling the lexical subtest among the teachers. Since there were lots of items in perceptive subtest, from different parts of speech (noun, adjective and verb) 1/3 of them were selected and the students have been told to answer them in 2 different sessions. The data were analyzed using descriptive analytic method. If a word was recognized by 80% of the informants, it was decided to be a core vocabulary (24 out of 30 in perceptive subtest and 4 out of 5 in lexical subtest). 219 and 81 words were listed to be among core vocabularies based on perceptive and lexical subtest respectively. 54 words were common in the lists. So, 246 words were estimated to be core vocabulary of educable mentally retarded preschoolers in Tehran.