Mental state attribution in agenesis of the corpus callosum versus high functioning autism

Previous studies showed that individuals with agenesis of the corpus callosum (ACC) exhibit social processing deficits resulting in difficulties with social interactions and communication. The current study examined attribution of mental states based on biological motion in 7 adults with ACC (ages 19--38, VIQ range 81--115, PIQ range 86--135) compared to 10 high functioning adults with autism spectrum disorder (ages 23--46, VIQ range 88--119, PIQ range 75--124) and 12 normal controls (ages 20--44, VIQ range 104--124, PIQ range 104--124) on the Castelli Animation Test. Analyses of variance analyzing the means scores of mental state attribution language, accuracy of descriptions given, and length of responses were conducted comparing each pair of groups: ACC and control groups, autism and control groups, and ACC and autism groups. Individuals with ACC had greater difficulty attributing mental states compared to normal controls. Specifically, the ACC group used less language of intentionality. Even when using mental state attribution language, the descriptions given by the ACC group were less accurate in describing the various animations. Though similar in many aspects of their performance on the Castelli Animation Test, the individuals with ACC demonstrated more attribution of mental state than individuals with autism for animation clips in the theory of mind (ToM) category. It might be hypothesized that the deficits in social processing of the individuals with ACC may be attributed to more basic neurocognitive deficits in complex and novel problem solving, but further research will be necessary to clarify this relationship.