COGNITIVE MODELING OF FACE PROCESSING - EVIDENCE FROM ALZHEIMER PATIENTS

This is a prospective neuropsychological study on Face processing in A lzheimer's disease (AD), The aim was to assess the prevalence and the nature of face processing disorders in AD, and at investigating possib le inter-test dissociations within the framework of currently used fac e processing models. A standardized four-test battery of unknown Face discrimination and familiar face recognition was given to 30 mildly de teriorated patients with AD. Half of the patients performed below the cut-off in at least one of the tests. Deficits in familiar face recogn ition tests were more frequently observed than deficits in unknown fac e discrimination rests. There was no correlation between impairment of face processing and overall cognitive impairment or visual disorders. A multiple single case approach allowed us to elicit statistically wa rranted double dissociations between tasks assessing unknown face disc rimination and tasks assessing familiar face recognition. Moreover, th e ability to decide whether or not a stimulus is a face or a non-face has proven to be a nonmandatory step to further process the face stimu li. All together, these findings support the hypothesis that distinct pathways are involved in the processing of unknown and familiar faces, as posited by Bruce and Young [Br. J. Psychol. 77, 305-327, 1986].