Categorical Speech Perception in Adults with Autism Spectrum Conditions

This study tested whether individuals with autism spectrum conditions (n = 23) show enhanced discrimination of acoustic differences that signal a linguistic contrast (i.e., /g/ versus /k/ as in 'goat' and 'coat') and whether they process such differences in a less categorical fashion as compared with 23 IQ-matched typically developed adults. Tasks administered were nonverbal IQ, verbal IQ, 5 language measures, a speech perception task, and the ADOS. The speech perception task measured the discrimination of paired exemplars along the /g/-/k/ continuum. Individuals with autism spectrum conditions did not show enhanced discrimination of speech perception. Categorical speech perception was correlated with verbal ability of reading, lexical decision, and verbal IQ in individuals with autism spectrum conditions.