Semantic integration during metaphor comprehension in Asperger syndrome

Previous research indicates severe disabilities in processing figurative language in people diagnosed on the autism spectrum disorders. However, this aspect of language comprehension in Asperger syndrome (AS) specifically has rarely been the subject of formal study. The present study aimed to examine the possibility that in addition to their pragmatic deficits, the difficulties in the comprehension of metaphors in AS may be explained by deficient linguistic information processing. Specifically, we aimed to examine whether a deficient semantic integration process underlies the difficulties in metaphor comprehension frequently experienced by persons with AS. The semantic integration process of sixteen AS participants and sixteen matched controls was examined using event related potentials (ERPs). N400 amplitude served as an index for degree of effort invested in the semantic integration process of two-word expressions denoting literal, conventional metaphoric, and novel metaphoric meaning, as well as unrelated word pairs. Large N400 amplitudes for both novel and conventional metaphors demonstrated the greater difficulties in metaphor comprehension in the AS participants as compared to controls. Findings suggest that differences in linguistic information processing cause difficulties in metaphor comprehension in AS.