Face processing in Pervasive Developmental Disorder (PDD): the roles of expertise and spatial frequency.

Both a reduced face expertise and a basic abnormality in visual information, e.g. spatial frequency, processing have been proposed as possible causes of the abnormal face processing in Pervasive Developmental Disorder (PDD). This study investigated both the roles of expertise and spatial frequency for face processing in PDD. Event-related potentials (ERPs) and dipole sources were measured in response to (upright/inverted) high- and low-pass filtered faces, houses, and stimuli for which children with PDD were experts. ERP analyses for specific posterior electrodes showed no differences between children with PDD and matched controls, but source analyses did. These showed that controls activated specialized brain sources for the processing of faces, which was dependent on low spatial frequency content. However, children with PDD did not. Importantly, present results argue against the idea that this is due to a reduced face expertise on the part of the children with PDD, but instead support an abnormality in spatial frequency processing.