Do YOU you have 'face blindness'? Take this 20-point test to find out...

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.