Automatic without autonomic responses to familiar faces: Differential components of covert face recognition in a case of Capgras delusion

Introduction. This study was designed to elucidate the relationship between different types of covert face recognition. Some patients with prosopagnosia (i.e., the profound inability to recognise previously familiar faces) nonetheless evince autonomic face recognition (elevated skin-conductance levels to familiar faces) or behavioural indices of covert recognition (i.e., priming; interference effects; matching effects; face-name learning). One prosopagnosic patient revealed both autonomic and behavioural covert face recognition - Which suggests they may arise from some common basis. Method. To test this claim a patient with the Capgras delusion (i.e., holding the belief that others have been replaced by impostors, etc.) was tested on each type of covert face recognition and her results compared with age-matched controls. We know that the Capgras delusion is characterised by good overt or conscious face recognition coupled with the absence of autonomic discrimination between familiar and unfamiliar faces. The question addressed here was whether, compared with age- and gender-matched controls, the patient, B.P., would show neither autonomic nor behavioural covert face recognition. Results. The answer was that, although she showed no autonomic discrimination, her performance on a priming task and a test of face/name interference were normal. The controls, as expected, revealed covert face recognition on both the autonomic and behavioural measures. Conclusions. The results imply in B.P. a clear dissociation between autonomic and behavioural measures of covert face recognition. The theoretical implications of these results are discussed.