Concept formation, problem solving and memory encoding abilities in individuals with congenital agenesis of the corpus callosum and normal intelligence

While individuals with congenital agenesis of the corpus callosum can, in some cases, perform normally on standardized intelligence tests, they nevertheless seem to have deficits in other domains of fluid intelligence. This study examined the role of the corpus callosum in processing complex novel problem solving tasks, concept formation and memory encoding through the assessment of adults with agenesis of the corpus callosum (ACC). Neuropsychological measures (Wisconsin Card Sorting Test, Halstead Categories Test, Raven's Progressive Matrices, Complex Figure Drawing Tasks and Letter and Number series) with varying levels of complexity were administered to 8 patients with complete ACC to ascertain possible deficits in problem solving abilities with increasing task complexity. The results indicate that subjects with ACC experience significant cognitive deficits related to concept formation and higher levels of problem solving abilities. They performed worse than controls matched for IQ, gender and age on all tests administered. On the two more complex versions of the RPM, subjects with ACC performed significantly worse than would be expected based on their IQ.