Verbal fluency as a function of time in autism spectrum disorder: An impairment of initiation processes?

In the present study, we aimed to evaluate the hypothesis that the reported discrepancy in the performance of verbal fluency in individuals with autism spectrum disorder (ASD), characterized by an overall word productivity impairment with normal clustering and switching abilities, may be due to an initiation deficit. In the present study, we evaluated the temporal dynamics of both letter and semantic verbal fluency tasks in a sample of 20 young adults with high-functioning ASD compared with a sample of 20 gender-, age-, education-, and verbal-IQ-matched participants. We first compared both the word productivity and the qualitative analysis of clustering and switching abilities during the entire task to replicate the discrepancy reported in the literature. Importantly, we next analyzed both word productivity and clustering and switching abilities in two time intervals (0-30 s and 31-60 s), as it was our primary interest to evaluate the functioning of the initial component of word retrieval. Directly supporting the idea that the discrepancy found between an impairment in global word productivity combined with normal clustering and switching strategies is due to an activation and initiation deficit, we observed an abnormal performance for the ASD group in the first time period only. We interpreted these results to be preliminary findings of deficits in initiation processes in ASD.