Face processing impairments and delusional misidentification

We report detailed investigations of the face processing abilities of four patients who had shown symptoms involving delusional misidentification. One (GC) was diagnosed as a Frégoli case, and the other three (SL, GS, and JS) by symptoms of intermetamorphosis. The face processing tasks examined their ability to recognize emotional facial expressions, identify familiar faces, match photographs of unfamiliar faces, and remember photographs of faces of unfamiliar people. The Frégoli patient (GC) was impaired at identifying familiar faces, and severely impaired at matching photographs of unfamiliar people wearing different disguises to undisguised views. Two of the intermetamorphosis patients (SL and GS) also showed impaired face processing abilities, but the third US) performed all tests at a normal level. These findings constrain conceptions of the relation between delusional misidentification, face processing impairment, and brain injury.