Face Recognition: Impairments in Prosopagnosia
Prosopagnosia, also called face blindness, is a neuropsychological condition that refers to impairment in the recognition of faces. Although prosopagnosic patients suffer from other types of recognition impairments (place recognition, car recognition, facial expression of emotion, est.), they experience face recognition problems above or over other types impairments. Prosopagnosia occurs without intellectual, sensory or cognitive impairments; in other words, people with prosopagnosia can still recognize people from non-facial cues. They cannot recognize familiar people by their faces alone, and often use alternative routes to alleviate the effects of this impairment. These routes include
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Like acquired prosopagnosia developmental prosopagnosia appears functional deficits on the basis of brain imaging studies. For instance, Hadjikhani and de Gelder (2002) noted that two regions in human extra striate are essential to normal face recognition. One of these is located in midfusiform gyrus known as the fusiform face area (FFA), the other in inferior occipital gyrus (IOG). In their study (Hadjikhani & de Gelder, 2002) there were 3 patients (one is a “pure” developmental prosopagnosic, while the other two suffered from close head injury in childhood) with severely impaired face recognition. None of these patients showed structural abnormalities on the basis of brain scans. However, they showed functional deficits of FFA and IOG; that is, these two regions did not evince stronger responses to faces than objects like normal subjects. In additional, patients showed a partly normal pattern of activation during objects viewing, and they have no difficulties discriminating faces from objects. Thus, these finding suggests that their lack of normal FFA and IOG involves inability for face recognition but not for face detection.
Prosopagnosia and a functional model
Prosopagnosia is not simply a mild agnosia; in fact, people with prosopagnosia lose the ability to recognize faces but relatively preserve the intact ability to recognize objects.In contrast, McCarthy and Warrington (as cited in Farah &