Cerebral lateralisation at different stages of facial processing.

Two experiments are reported which explore the cerebral lateralisation of different stages of facial processing. In Experiment 1 subjects were briefly presented with either upright or inverted Mooney faces to either the left or right visual field. The subjects' task was to decide whether or not the stimulus had the configuration of a face. The data showed a left visual field superiority in performing this task. In Experiment 2 subjects were briefly presented with line drawings of faces to either the left or right visual field. On half the trials all the facial features were intact whilst in the remainder one feature had been replaced by an anomalous feature in the same position. The subjects were required to detect whether an anomalous feature was present or not and this task produced a right visual field superiority. These data argue against a global right hemisphere superiority in facial processing and suggest, instead, that hemispheric superiority will vary depending on the stage of facial analysis investigated. On the basis of these and other recent findings it would appear that the right hemisphere is advantaged for the holistic stages of facial processing whilst the left-hemisphere has superiority for analysis at the level of individual features. However, the data are ambiguous as to whether the hemispheric differences detected reflect face-specific or general processing characteristics of the cerebral hemispheres.