Lots of us are bad with remembering names, but can still pick out a past colleague or old flame when they pop up on social media.
However, a new study from Harvard University has found that up to 5.42 per cent of people struggle with the opposite problem.
‘Prosopagnosia’, or face blindness, is a disorder that makes you unable to recognise faces you’ve seen before, including those of friends and family.
It can also result in you being unable to identify yourself in pictures or the mirror, or feeling like you know complete strangers.
Last year, Brad Pitt detailed his experience with the condition, admitting that ‘nobody believes’ him when he talks about it.
‘Prosopagnosia’, or face blindness, is a disorder that makes the person not be able to recognise faces they have seen before, including those of friends and family (stock image)
Nursery nurse Hannah Read, who has the worst case of face blindness in UK, said that ‘every face looks the same’ and is just ‘two eyes, a nose and a mouth’.
Those with the disorder may cope by using alternative ways to recognise people, such as remembering the way they walk, or their hairstyle, voice or clothing.
It is thought to be the result of abnormalities, damage, or impairment in the right fusiform gyrus – a fold in the brain that appears to coordinate facial perception and memory.
Prosopagnosia can result from stroke, traumatic brain injury, or some neurodegenerative diseases, but in some cases it is present at birth.
It appears to run in families, which makes it likely to be the result of a genetic mutation or deletion.
While it is commonly cited that between two and 2.5 per cent of the world’s population has some form of face blindness, researchers set out to find its true prevalence in a new study, published in the Diagnostic and Statistical Manual of Mental Disorders.
They recruited 3,341 individuals to take three different online surveys, where the first asked them to describe their own experiences recognising faces in their day-to-day lives.
The next two were then objective tests which probed their ability to learn new faces and recognise famous ones respectively.
Results showed that 31 individuals had a severe form of prosopagnosia, while 72 had a mild form – a total of three per cent of the study participants.
They also found that participants who could easily recognise faces and those who could not were not obviously distinguishable.
Instead, most of them fell somewhere on a spectrum of severity and presentation, in a similar way to other developmental disorders like autism and Alzheimer’s disease.
Last year, Brad Pitt detailed his experience with face blindness, admitting that ‘nobody believes’ him when he talks about it
The researchers then used different diagnostic criteria to assess some of the participants with face blindness.
Depending on how strict these were, they identified prosopagnosia affected between 0.13 and 5.42 per cent of the group.
Interestingly, it was also found that the stricter criteria did not always identify the individuals who were poorest at recognising faces.
As a result, they concluded that scientists looking into the disorder should relax their threshold for diagnosis, and split people by ‘mild’ or ‘major’ case.
Diagnostic criteria for face blindness vary, but researchers from King’s College London have created a short questionnaire for people who suspect they have it.
It asks people how strongly they agree with phrases including ‘I often mistake people I have met before for strangers’ or ‘I sometimes find movies hard to follow because of difficulties recognising characters’.
Other questions include: ‘When I was at school I struggled to recognise my classmates’ or ‘When people change their hairstyle, or wear hats, I have problems recognising them.’
Each question is scored out of five, giving a total score of up to 100. This final score could be used to help determine the severity of face-blindness.
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