Although the "big brain" theory of autism is appealing and may go some way toward accounting for the lack of topdown modulation observed as WCC, findings are mixed and again suggestive of heterogeneity. In a study of 47 children with ASD conducted by TagerFlusberg and Joseph (2003) only 14% of the sample showed evidence of large brain size. However, there was a relationship between head circumference (an indirect measure of brain size) and IQ profile. Specifically, head circumference was significantly larger in children with higher performance IQ than verbal IQ, than in those with higher performance than verbal IQ or those with balanced profiles