Categorization of disoriented faces in the cerebral hemispheres of normal and commissurotomized subjects

We examined the capacity of the cerebral hemispheres to process faces that deviate from canonical perspective. In Experiment 1, normal Ss performed a gender categorization of faces presented at varying angular orientations in the left visual field (LVF) or right visual field (RVF). Orientation affected processing speed, more so in the RVF than in the LVF. The function relating reaction times to disorientation of the faces was approximately monotonic and reflected the increased difficulty in extracting relevant configurational information as the faces were rotated from canonical perspective. In Experiment 2, 3 commissurotomized Ss performed the same task. They responded above chance in the 2 visual fields, and the pattern of their results was similar to that obtained with the normal Ss, but the effect of disorientation was considerably more pronounced. It is suggested that the right hemisphere contribution becomes more critical the further the visual pattern departs from conventional view. Issues regarding the specification of processes correcting for disorientation and comparison of normal and commissurotomized Ss are discussed.