Behavioural and physiological evidence for covert face recognition in a prosopagnosic patient.

In a previous report, Bauer (1984) described the patient LF, who was unable to recognise familiar faces. Despite the inability to verbally identify familiar faces, psychophysiological examination revealed preserved covert processing of facial identity. Subsequent studies have demonstrated covert face recognition using behavioural tasks. Investigations of the patient PH showed normal face familiarity effects on matching, interference, priming, and learning tasks, while overt recognition was completely absent (De Haan, Young and Newcombe, 1987b). The use of different methodologies has led to different theoretical conceptualisation of the "covert recognition" phenomenon. Until now, no individual patient has been exposed to both methodologies. In this study we evaluated LF, who shows psychophysiological evidence of covert recognition, using behavioural tasks previously used with PH. The results reveal clear behavioural evidence of preserved face recognition without awareness. These findings suggest that both methodologies tap similar phenomena, and have important implications for theoretical models of covert face recognition. A conceptual model designed to integrate psychophysiological and behavioural evidence of covert face recognition is proposed.