Executive functions in Persian-speaking preschool children with speech sound disorders and comparison with their typically developing peers

This study aimed to compare working memory, inhibitory control, and cognitive flexibility, the core components of executive functions, among two prevalent subtypes of preschool children with speech sound disorder, i.e., phonological delay (n = 16) and consistent phonological disorder (n = 15), and a group of typically developing children (n = 18). The correlation between executive function components and the accuracy of speech sound production were also investigated. Nonword repetition task and syllable repetition task were used to evaluate the phonological loop of working memory. Backward digit span was administered to examine the central executive of working memory. Cognitive flexibility was assessed using the second selection of the flexible item selection task and inhibitory control using Stroop-like and Go/No-Go tasks. The percentage consonants correct was applied to calculate the accuracy of speech sound production. Results of a one-way multivariate analysis of covariance revealed statistically significant differences between groups in the combined dependent variables after controlling for age (F(14, 80) = 17.289, p < .001, Pillai’s trace = 1.503, partial ηƞ2 = .752). Typically developing children outperformed in all measurements of executive functions than both speech sound disorder subgroups. Moreover, children with phonological delay performed better in nonword repetition and corrected responses of Stroop-like than consistent phonological disorder group. All executive function measurements also correlated with speech sound production. The results of the present study highlight the importance of including domain-general cognitive skills in current assessment protocols for children with phonological delay and consistent phonological disorders.