THE INVERTED FACE INVERSION EFFECT IN PROSOPAGNOSIA - EVIDENCE FOR MANDATORY, FACE-SPECIFIC PERCEPTUAL MECHANISMS

Does the human visual system contain a specialized system for face rec ognition, not used for the recognition of other objects? This question was addressed using the ''face inversion effect'' which refers to the loss of our normal proficiency at face perception when faces are inve rted. We found that a prosopagnosic subject paradoxically performed be tter at matching inverted faces than upright faces, the opposite of th e normal ''face inversion effect''. The fact that his impairment was m ost pronounced with the stimuli for which normal subjects show the gre atest proficiency in face perception provides evidence of a neurologic ally localized module for upright face recognition in humans. An addit ional implication of these data is that specialized systems may contro l behavior even when they are malfunctioning and therefore maladeaptiv e, consistent with the mandatory operation of such systems according t o the ''modularity'' hypothesis of the cognitive architecture.