Partial damage to the recognition system might affect faces, but not objects if faces require an additional level of visual processing relative to objects. However, because human faces share the same basic features, it could also be argued that faces are simply very “difficult objects” to recognize. The existence of such cases can be used to suggest that a special system dedicated to faces that is not involved in object recognition has been damaged. Several acquired prosopagnosic patients have been reported with severe difficulties in identifying faces despite being able to recognize other classes of objects (e.g., McNeil and Warrington, 1993 Riddoch et al., 2008 Rivest et al., 2009 Rossion et al., 2011).
The theoretical implications of this pattern of performance for understanding the nature of acquired prosopagnosia are discussed. These preserved featural skills together with apparently intact visual imagery for faces allow him to identify a surprisingly large number of famous faces when unlimited time is available. This case appears to reflect the clearest example yet of an acquired prosopagnosic patient whose familiar face recognition deficit is caused by a severe configural processing deficit in the absence of any problems in featural processing. He shows evidence of impaired global processing but normal local processing of Navon figures. He also performs as accurately as controls at recognizing famous faces when fracturing conceals the configural information in the face. Nevertheless, he performs as accurately and quickly as controls at identifying inverted familiar and unfamiliar faces and can recognize famous faces from their external features. Formal testing indicates that he is also severely impaired at remembering pre-experimentally unfamiliar faces and that he takes an extremely long time to identify famous faces and to match unfamiliar faces.
We report the case of an individual with acquired prosopagnosia who experiences extreme difficulties in recognizing familiar faces in everyday life despite excellent object recognition skills.
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