Phonetic imitation by individuals with Autism Spectrum Disorders: Investigating the role of procedural and declarative memory

Abstract

This study investigates the role of procedural and declarative memory in phonetic imitation, by examining the word- and phoneme-specificity of imitation produced by individuals with autism spectrum disorders (ASD). Previous research has shown that individuals with ASD process language differently from the Neurotypical population [e.g., Ullman (2004), Walenski et al. (2006)], with Autistic individuals relying more on declarative memory. Previous work with the general population has shown a robust effect of phonetic convergence [e.g., Pardo (2006)], as well as generalization and weak word-specificity effects [Nielsen (2011)]. To test whether individuals with ASD exhibit increased specificity, we used Nielsen's (2011) experimental paradigm, which has been shown to elicit generalized phonetic imitation in the general population. A linear mixed effects regression analysis revealed that increased VOT on the modeled phoneme /p/ was imitated by both ASD and control groups [p < 0.05]. However, different patterns emerged in phoneme-level specificity: the control group exhibited sub-phonemic generalization (increasing VOT on /p/ and /k/), while the ASD group exhibited a phoneme-specific pattern (increasing VOT only on /p/) [p < 0.05]. Furthermore, a stronger trend toward word-specificity was observed within the ASD group. Taken together, these results confirm the earlier finding that ASD individuals exhibit greater reliance on declarative memory.