The neuropsychology of facial identity and facial expression in children with mental retardation.

We indirectly determined how children with mental retardation analyze facial identity and facial expression, and if these analyses of identity and expression were controlled by independent cognitive processes. In a reaction time study, 20 children with mild mental retardation were required to determine if simultaneously presented photographs of pairs of faces were pictures of the same person or of different people (identity matching), or to determine if the pairs of faces showed the same expressions or different expressions (expression matching). Faces of familiar and unfamiliar people were used as stimuli. For identity matching, reaction times were faster for familiar faces than for unfamiliar faces. For expression matching, there was no difference between familiar and unfamiliar faces. These results are consistent with neuropsychological findings from the general population indicating that analyses of facial expressions proceed independently from processes involved in establishing a person's identity. Our results suggest that the basic neuropsychological mechanisms that underlie cognitive processing of facial identity and facial expressions in children with mental retardation may be similar to those of people in the general population.