A LECTURER at the University of Bradford has developed a test that could help diagnose people who have "face blindness" - which means they cannot recognise other people.

Dr Andrew Logan, from the university's School of Optometry and Vision Science, hopes the test will make it easier for healthcare professionals to diagnose Prosopagnosia - a condition that affects as many as three in 100 people.

The condition means people can’t easily recognise differences between faces, even of close friends and family. It means they face embarrassment as they ignore people they know, social isolation, anxiety and depression.

People with the little known condition have been reported as being labelled ‘rude’ by co-workers because they fail to recognise them. And parents with the condition have even reported that they have difficulties recognising their own children in the school playground.

Those with the condition have to resort to recognising people by their clothing, voice or mannerisms.

Some people are born with face blindness, meaning they don't always realise they suffer from it. And Prosopagnosia can be passed on genetically, meaning it can effect different generations of the same family.

Dr Logan said: “For most of us, a brief glimpse of a face is enough to judge someone’s age, gender, ethnic background and to know whether or not that face is familiar.

"That we are so good at discriminating between faces is actually quite remarkable. After all, to a first approximation all faces are the same: two eyes, above a nose, above a mouth. Our visual system has evolved, however, to be very sensitive to subtle differences between faces and we are extremely accurate at recognising faces that are familiar to us.

“For some people, however, discriminating between faces is not so easy.”

Although treatments for the condition are not currently available, the earlier doctors can identify people as having Prosopagnosia, the earlier they can support them.

Dr Logan has been working with colleagues from Glasgow Caledonian University and York University, Toronto on a new test of face perception.

It involves presenting participants with four faces and asking them to identify the odd one out. It uses simplified face images, synthesised from real face photographs. Synthetic faces can be modified, making it easier or harder to match the face discrimination ability of patients.

The team tested 52 young adults with no known difficulties with face perception. They found a range of face discrimination thresholds, with some highly sensitive to small differences and others needing much larger differences to recognise unique faces. When repeating the test, they found it was reliable and repeatable.

They also tested a patient who reported lifelong difficulties with face recognition.

Dr Logan added: “Some existing tests are unable to measure the whole spectrum of face perception ability. In addition, some tests don’t exclude the possibility of other visual or cognitive problems, like poor memory. Our results show that the test is very reliable and can be performed in less than four minutes, making it suitable for clinicians to use.”

Dr Logan worked with Dr Gael Gordon and Professor Gunter Loffler from Glasgow Caledonian University and Professors Frances Wilkinson and Hugh Wilson from York University, Toronto, Canada.