WHAT IS SPECIAL ABOUT FACE RECOGNITION - 19 EXPERIMENTS ON A PERSON WITH VISUAL OBJECT AGNOSIA AND DYSLEXIA BUT NORMAL FACE RECOGNITION

In order to study face recognition in relative isolation from visual p rocesses that may also contribute to object recognition and reading, w e investigated CK, a man with normal face recognition but with object agnosia and dyslexia caused by a closed-head injury. We administered r ecognition tests of upright faces, of family resemblance, of age-trans formed faces, of caricatures, of cartoons, of inverted faces, and of f ace features, of disguised faces, of perceptually degraded faces, of f ractured faces, of faces parts, and of faces whose parts were made of objects. We compared CK's performance with that of at least 12 control participants. We found that CK performed as well as controls as long as the face was upright and retained the configurational integrity amo ng the internal facial features, the eyes, nose, and mouth. This held regardless of whether the face was disguised or degraded and whether t he face was represented as a photo, a caricature, a cartoon, or a face composed of objects. In the last case, CK perceived the face but, unl ike controls, was rarely aware that it was composed of objects. When t he face, or just the internal features, were inverted or when the conf igurational gestalt was broken by fracturing the face or misaligning t he top and bottom halves, CK's performance suffered far more than that of controls. We conclude that face recognition normally depends on tw o systems: (I) a holistic, face-specific system that is dependent on o rientation-specific coding of second-order relational features (intern al), which is intact in CK and (2) a part-based object-recognition sys tem, which is damaged in Cg and which contributes to face recognition when the face stimulus does not satisfy the domain-specific conditions needed to activate the face system.