Brief report: Further evidence for inner speech deficits in autism spectrum disorders.

Recent research indicates that individuals with autism do not effectively use inner speech during the completion of cognitive tasks. We used Articulatory Suppression (AS) to interfere with inner speech during completion of alternate items from the Tower of London (TOL). AS detrimentally affected TOL performance among typically developing (TD) adolescents (n = 25), but did not significantly diminish performance among adolescents with high functioning (IQ > 80) autism spectrum disorders (n = 28). Moreover, the TD group's TOL performance under AS was indistinguishable from the autism group's impaired baseline TOL performance. These findings suggest that diminished inner speech usage among individuals with high functioning autism spectrum disorders (relative to TD controls) may contribute to executive dysfunction associated with these disorders.