Brief report: Inner speech impairment in children with autism is associated with greater nonverbal than verbal skills.

We present a new analysis of Whitehouse, Maybery, and Durkin's (2006, Experiment 3) data on inner speech in children with autism (CWA). Because inner speech development is thought to depend on linguistically mediated social interaction, we hypothesized that children with both autism and a nonverbal > verbal (NV > V) skills profile would show the greatest inner speech impairment. CWA and typically developing controls (n = 23 in each group) undertook a timed mathematical task-switching test, known to benefit from inner speech use. Participants completed the task with and without articulatory suppression (AS), which disrupts inner speech. The hypothesis was supported: AS interference varied with cognitive profile among CWA but not among controls. Only the NV > V autism group showed no AS interference, indicating an inner speech impairment.