Abstract
LJ, a 16-year-old male, had no history of visual difficulties prior to an incident in November 2004. After posing for a photograph preceded by red eye reduction flashes and the normal flash, LJ became disoriented and sounds were distorted. His disorientation and hearing difficulty cleared up within a matter of minutes, but his face perception has been severely impaired ever since. In the preceding years, he suffered from several spells of disorientation, including one following exposure to a strobing light. Other than face perception, LJ is unaware of any difficulties resulting from the incident. He reads and plays the piano normally. LJ is a world-class juggler, and his juggling has not suffered. He reports no difficulties with object recognition in daily life, and he has performed normally on a wide range of object tests. In contrast, LJ now inhabits a lonely world devoid of meaningful facial information. He is unable to identify few previously familiar faces, and successful identifications rely on recognition of individual features and a process of inference. He performs very poorly on tests of emotional recognition and gender discrimination, and his attractiveness ratings are atypical and unreliable. Unlike most prosopagnosics with face-selective impairments, he fails tests of face detection. When shown six Arcimbaldo faces, which consist of a collection of objects in a face-like configuration, LJ was able to see only one of the faces and he did so quite slowly. LJ also reports no facial imagery. He performed normally on several flawed face tests so he does not appear to be malingering. His difficulties with faces extend to inverted faces as well. His results indicate that face perception mechanisms are sharply segregated from object perception mechanisms, face detection is not carried out by general-purpose recognition mechanisms, and inverted face processing involves the processes used with upright faces.