Prosopagnosia (also known as 'face blindness') refers to a severe deficit in recognizing familiar people from their face. While some people report a very selective impairment that only influences the recognition of faces, others find the deficit extends to the recognition of other stimuli, such as objects, cars, or animals. Many people also report deficits in other aspects of face processing, such as judging age or gender, recognising certain emotional expressions, or following the direction of a person's eye gaze. Finally, a substantial proportion of prosopagnosics report navigational difficulties.
Some prosopagnosics cope well with the face recognition impairment, and develop elaborate compensatory mechanisms to help them function effectively in everyday life. For others, however, the condition has a much greater impact on daily functioning. Some prosopagnosics have reported avoidance of social interactions, problems with interpersonal relationships, damage to career, and even depression. In extreme cases, prosopagnosics may develop social anxiety disorder, characterized by fear and avoidance of social situations that may cause embarrassment.
Until recently, it was thought that very few people suffer from prosopagnosia. The condition has traditionally been studied in individuals who acquire the disorder following neurological damage (typically from stroke or head injury), and a handful of case studies were reported in the literature in the 20th century. However, it has recently become clear that many more people suffer from prosopagnosia without experiencing neurological damage. This form of the disorder is commonly referred to as "developmental" or "congenital" prosopagnosia, and these individuals simply fail to develop normal face processing abilities despite normal intellectual and perceptual functions. Developmental prosopagnosics have suffered from the face recognition impairment for most of their lives, perhaps since birth. Recent evidence suggests there may be a genetic contribution to developmental prosopagnosia, and several case studies report at least one first-degree relative who also suffers from the face recognition impairment.
As explained above, acquired prosopagnosia following brain damage is rare. However, developmental prosopagnosia appears to be much more common. In recent years, a flurry of media attention has raised awareness of the disorder, and thousands of people who believe they have prosopagnosia have approached researchers throughout the world. However, little work has resulted in a formal estimate of the prevalence of developmental prosopagnosia. A recent study conducted in Germany surveyed the face recognition abilities of a large group of students, and reported a prevalence rate of 2-2.5%. That is, as many as one in 50 people may suffer from developmental prosopagnosia. If this figure is correct, there may be 1.5 million prosopagnosics in the UK alone. Even if this is an overestimation, a prevalence of just 1% would indicate that 600 000 people suffer from the disorder.
It is true that many people with autistic spectrum disorders also suffer from face recognition impairments. Problems with face processing have also been reported in other developmental disorders such as Williams' syndrome and Turner's syndrome. There are various theories concerned with this pattern of presentation, and some researchers believe the face recognition impairment can be attributed to a lack of social interest, and others that perceptual-processing strategy or impaired visuo-spatial skills may be the critical factor. However, while some individuals with prosopagnosia report severe social consequences resulting from the face processing impairment, these are not necessarily an indicator of a concurrent neuro-developmental disorder. On the contrary, there have been reports of a misdiagnosis of high-functioning autism when the underlying impairment is actually prosopagnosia. Importantly, many developmental prosopagnosics do not fulfil the diagnostic criteria of an autistic spectrum disorder.
Many people occasionally fail to recognise a familiar face, or even mistake an unknown person for someone they know. However, individuals with prosopagnosia have a severe face recognition deficit, affecting even the most familiar faces, such as their spouse or children. This failure to recognise familiar faces occurs every day, but many prosopagnosics have developed compensatory strategies to help with person recognition. For example, they might recognise a person by their hairstyle, clothing or gait, or simply because they expect to see a person within a given context. However, if they unexpectedly encounter a familiar person, these compensatory strategies often break down. If you believe you may suffer from prosopagnosia and live within travelling distance of Bournemouth University, we may be able to offer you a formal testing session and the opportunity to take part in our research if you wish to. You can register your details with us here.
There is no formal treatment for prosopagnosia. However, many researchers are now working in this area, and you may be able to take part in a study investigating prosopagnosia. Some research focuses on advancing our understanding of the causes and basis of prosopagnosia, whereas other investigators are examining the effectiveness of training programmes designed to improve face recognition. If you believe you have prosopagnosia and would like to take part in some research investigating intervention techniques, please register here. If you live close to our laboratory in Bournemouth and don't mind travelling to us (travel expenses can normally be reimbursed), we will do our best to accommodate you within our current research programmes. However, we also have collaborators in other parts of the UK, Australia and America, and may be able to put you in touch with a researcher who is based closer to your home.
Many people with prosopagnosia report compensatory strategies that can often help them circumvent their difficulties. For instance, teachers have described how they use classroom seating plans to identify their pupils, or even recognize different children by an external cue, such as their backpacks. Other elaborate compensatory strategies have been described, such as the use of jewellery, clothing, voice or gait to recognize a familiar person. Of course these strategies do not always work, and particularly break down when a person is met out of context and logic cannot be combined with these external cues. If you would like to read more about the various strategies that people have found to be useful cues to recognition, why not check out and even contribute to our Discussion Forum on this topic.