Research reveals why some people can’t recognize faces
Most of us can recognize the faces of people we’ve met quickly and effortlessly...
Most of us can recognize the faces of people we’ve met quickly and effortlessly. But the ease with which we do this belies the complex brain mechanisms behind it, which researchers are only now beginning to understand. A team of researchers at Birkbeck, University of London have this week published the results of their investigation into a condition known as prosopagnosia, or face blindness, in the journal Brain. People with face blindness are unable to recognize faces, including those of their family, or sometimes even their own face in the mirror.
The study, funded by the Economic and Social Research Council, looked at how information processing goes wrong in the brains of people with face blindness, as there are several stages in the process of face perception and recognition.
Professor Martin Eimer, who leads the team at Birkbeck, said: “Prosopagnosia is a specific problem with face recognition that does not affect most other cognitive processes, such as recognizing voices or other objects like cars or houses. For people with face blindness, it is only faces that are the big problem.”
In some rare cases, prosopagnosia is the result of brain damage, by a stroke, for example. But there are many more people who fail to develop normal face recognition abilities, without any history of neurological damage. “People with developmental prosopagnosia are intelligent, have good jobs, and get along fine, but they just cannot recognize faces. Because they have never been able to recognize faces and don’t realize that how they perceive faces is different to a normal person, many of them are not diagnosed until adulthood”, says Eimer.
In the experiment published in Brain, Eimer and his team recorded the electroencephalogram (EEG) from people with developmental prosopagnosia while they were shown photographs of well-known celebrities (such as actors, politicians, comedians, musicians, sports personalities, and members of the Royal family), as well as photographs of non-famous faces. The EEG enabled the researchers to pinpoint the exact timing of the brain’s electrical response to a specific face.
As expected, people with face blindness could not recognize most famous faces – not even the faces of politicians that featured in the news almost every day. However, their brain often seemed to recognize these faces. “When we measured electrical brain responses to famous faces, we found a clear signal that emerged very rapidly”, explains Eimer. “In people with intact face processing, this signal indicates successful face recognition. For half of the people with prosopagnosia that were tested, this response was there, even when they told us that they did not recognize a face”. These findings suggest that many people with face blindness unconsciously recognize famous faces at an early stage of face processing, but that this information is later lost.
Professor Eimer comments: “The fact that half of the subjects showed subconscious face recognition, and the other half did not, shows that developmental prosopagnosia can have different causes in different people. The posterior part of the brain contains several different face processing areas, and a malfunction of any of these can cause face recognition problems. It is also possible that connections between these areas might be interrupted, which means that there may be many different types of prosopagnosia”.
Further information:
The Economic and Social Research Council (ESRC) is the UK's largest organisation for funding research on economic and social issues. It supports independent, high quality research which has an impact on business, the public sector and the third sector. The ESRC’s total budget for 2011/12 is £203 million. At any one time the ESRC supports over 4,000 researchers and postgraduate students in academic institutions and independent research institutes.