Prosopagnosia

Young et al 1993

Acquired Prosopagnosia is supported by a study by Young et al 1993 it was found for example that in 34 ex service men who had missile wounds to back of brain they all had difficulty with face recognition and in 3 different ways. Firstly they were poor at familiar face recognition, secondly they were poor at matching faces and thirdly they had difficulty in reading facial expression. These results show that in relation to face recognition that there diff parts of the brain process/ routes in the brain which process diff parts of face recognition.

Grueter et al (2007)

Grueter et al studied between 2 and 4 generations of seven affected families and found 38 cases of prosopagnosia. The participants' scores on a recognition test were below those of an age and education matched comparison group which suggests a significant genetic contribution to face recognition skills.

Grueter et al (2007) - Evaluation

However, there are methodological problems with this study. Although 38 cases were initially identified only 8 participants continued to the end of the study. This means that the study is not representative to the wider population and further studies need to be undertaken until the results considered reliable and can be generalise further.

McNeil and Warrington (1993) - Evaluation

However, there are problems with the methodology of this study. Case studies are of one individual and their brain damage may be very specific and hence different to other individuals so the results from case studies cannot be generalised to other groups. Case studies cannot be replicated as each person's circumstances are unique so we cannot check the reliability of the results.

McNeil and Warrington (1993)

McNeil and Warrington studied WJ who developed prosopagnosia after a series of strokes. He was unable to recognise human faces and distinguish a famous person from non-famous people, but when he changed careers to become a sheep farmer he could distinguish between his sheep, which shows that face and object recognition use different parts of the brain and only damage to the area responsible for face recognition causes prosopagnosia.

Developmental Prosopagnosia

One explanation for prosopagnosia (a type of associative agnosia) is that it is caused by a mutation of a single faulty gene, which is inherited by about 2.5% of the population. This is called developmental prosopagnosia.

Prosopagnosia

Prosopagnosia (sometimes known as face blindness) is a disorder of face perception where the ability to recognize faces is impaired, while the ability to recognize other objects may be relatively intact. However, most prosopagnosics have some problem with object recognition as well. Some people with the disorder are unable to recognise their own face. Prosopagnosia is not related to memory dysfunction, memory loss, impaired vision, or learning disabilities. Some degree of prosopagnosia is often present in children with autism and Asperger's syndrome, and may be the cause of their impaired social development

Ethical Issue

There may be ethical issues with research used in this area. For example, case studies of brain damaged patients may cause distress to the participant hence psychological harm as they may consider discussion of their condition embarrassing (as found in Grueter et al 2007). This then may cause the participant to either produce unreliable results or even drop out of the study - invalidating their results.

Nature vs. Nurture

These two explanations for prosopagnosia given above both support the nature side of the nature/nurture debate, as they are arguing that a condition such as prosopagnosia is caused by physiology, on the one hand that a mutation of a gene could cause the disorder and on the other hand, that a particular area of the brain has been damaged. There is, however, some evidence that the environment and learning may also influence how our brain processes information, for example the study which shows that any area of expertise uses the FFA may mean that what is processed using the FFA depends on what activities we engage in and what our interests are.

Acquired Prosopagnosia

This explanation is that prosopagnosia is an acquired disorder and the result of brain damage to this specific part of the brain. When we perceive something, the right fusiform gyrus (FFA) decides if the object is a face, and if it is familiar. If it finds a match then the anterior temporal cortex (ATC) brings up a store of facts about the person which also assists with the identification process. The inferior occipital gyri at the back of the brain helps to identify physical changes, such as wrinkles or tiredness. The specific brain area usually associated with prosopagnosia is the FFA. Alternatively, others argue that prosopagnosia is caused by damage to an overall system which processes both objects and faces.