Autistic traits predict individual differences in speech categorization

Investigating individual differences in speech perception using measures of “autistic” traits in neurotypicals can gauge natural variability in speech processing [M. Stewart and M. Ota, Cognition 109, 157–162 (2008)]. Using the autism‐spectrum quotient (AQ) [Baron‐Cohen et al., J. Autism & Dev. Disord. 31, 5–25 (2001)], which measures autistic traits in neurotypicals, we investigated individual differences in context‐dependent speech processing. Twenty‐eight neurotypicals categorized a nine‐step da/ga series in the context of non‐speech tone precursors [following L. Holt, Psychol. Sci. 16, 305–312 (2005)] and completed the AQ. Context included three tone groups, including relatively high (shift toward ga), medium, and low (shift toward da) tones. Overall, the temporally adjacent tone grouping shifted perception more than distant context (p<0.001). Effects correlated with AQ (r=0.53). Lower AQ (fewer autistic traits) is associated with near‐zero context dependence for endpoint categorization and large context‐dependence for ambiguous speech‐target categorization. Higher AQ is associated with intermediate influence of context across the series. Individual differences in context‐dependent phonetic processing can be predicted from a personality trait scale, suggesting that phonetic processing is not immune from the influence of higher‐order cognitive processes associated with these traits or that lower‐level perceptual processing varies with these traits.