Prosopagnosia

Visual agnosias The inability to recognise familiar objects presented visually is known as visual agnosia. There are two main types: Apperceptive agnosia – a failure to recognise due to impaired visual perception. This implies a physiological problem in the visual system. Associative agnosia – intact visual perception but failure to access the relevant knowledge from memory.

Prosopagnosia This is a form of associative agnosia. The inability to recognise faces. A person with prosopagnosia could accurately describe the features of someone they were looking at but not be able to recognise them as a son, daughter or partner, or friend.

Is it a unique face-specific problem? Barton found that the fusiform face area (FFA) – see diagram in your notes, was damaged in people with prosopagnosia but less so in patients with object recognition problems. Farah argues that face recognition is different to other forms of recognition – faces are special, and are processed separately from objects, this process can be selectively damaged.

Not a face-specific problem This is the opposite view, according to Gauthier (1999) people with prosopagnosia can have other object recognition problems. The Bruce and Young model insists that faces are processed in a modular way but there is an alternative argument for holistic processing, where recognition is made using the overall shape and structure of objects and faces.

Evaluation Case studies dominate research in this area. Theses patients work with one researcher so corroborative evidence is lacking, Farah claims this is a lack of inter-laboratory verification. PET and fMRI scanning shows brain activity in living patients, it can provide scientific evidence but there is still much to be learnt about the interpretation of these scans and their relevance to prosopagnosia.

Farah (1995) case study L.H. fully supports specific mechanisms for face recognition as he could identify objects but not faces. However other case studies disagree. Gradually there is an accumulation of evidence to support the view that faces are not special. Gauthier and Tarr (2002) argue that it comes down to expertise, the FFA is activated when tested on things people know a lot about, e.g. in birdwatchers it would be birds, not cars. Eysenck argues that faces are not as special as psychologists once thought they were.