Lexical effects on speech perception in individuals with “autistic” traits

It has been claimed that Autism Spectrum Disorder (ASD) is characterized by a limited ability to process perceptual stimuli in reference to the contextual information of the percept. Such a connection between a nonholistic processing style and behavioral traits associated with ASD is thought to exist also within the neurotypical population albeit in a more subtle way. We examined this hypothesis with respect to auditory speech perception, by testing whether the extent to which phonetic categorization shifts to make the percept a known word (i.e., the ‘Ganong effect’) is weakened as a function of autistic traits in neurotypicals. Fifty-five university students were given the Autism-Spectrum Quotient (AQ) and a segment identification test using two word-to-nonword Voice Onset Time (VOT) continua (kiss-giss and gift-kift). A significant negative correlation was found between the total AQ score and the identification shift that occurred between the continua. The AQ score did not correlate with scores on separately administered VOT discrimination, auditory lexical decision, or verbal IQ, thus ruling out enhanced auditory sensitivity, slower lexical access or verbal intelligence as explanations of the AQ-related shift in phonetic categorization.