Examining expression of lexical categories in Farsi- speaking Children with specific language impairment

Perception and expression of word categories is a cognitive linguistic skill which develops gradually. Regarding the children with specific language impairment (SLI)، they are more vulnerable in some linguistic areas; it was hypothesized that the perception and production of category labels such as their semantic skill could be influenced. The purpose of this study was to compare categorization system between SLI school-aged children with those of normal peers. This cross-sectional analytic study consisted of 16 SLI and 16 normal children from first to third grade of school. The subject and control groups sampled in easy access and randomized consequently. SLI children were screened based on more than twelve (12) scores discrepancies between their verbal and non-verbal performance with the primacy of nonverbal score over verbal score on WISC-R. Linguistic behaviors of the two groups were assessed by using number of different words and mean length of utterance in terms of morphemes. Finally، the categorization task with fourteen (14) high frequency nouns from seven (7) categories conducted and their behavioral data compared statistically by t-test. SLI children demonstrated significant difference in word definition by labeling of specific categories compared to normal peers (P=0. 001). Two groups were not showing a significantly differerance in other ways of naming categories، although the pattern of their responses was different. Regarding the significant reduced ability of SLI children in category expression، it was suggested that the specific category expression could be used as a diagnostic indicator and as an intervention measure in SLI children.