Unilateral damage to the right cerebral hemisphere disrupts the apprehension of whole faces and their component parts

Although most cases of acquired prosopagnosia are accompanied by bilateral brain lesions, a number also arise following right unilateral lesions. The prevailing consensus is that right hemisphere damage disrupts the configural apprehension of faces, which in turn forces a reliance on part-based processing. Here we describe a patient who following right hemisphere damage is not only unable to apprehend the configural aspects of faces, but is also unable to apprehend their component parts when these are presented within a whole, upright face. Intriguingly, the patient is able to apprehend face parts when these are presented in isolation, within inverted faces, or in unfamiliar, scrambled arrangements. Furthermore, the patient can make use of configural information to detect local changes in non-face stimuli. The findings uncover a hitherto unreported form of impairment following right unilateral damage, and raise questions about the role of the left hemisphere in processing local information.