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Prosopagnosia About face Dec 2nd 2004 From The Economist print edition Researchers are exploring how and where in the brain people recognise faces. This could be helpful to those who cannot recall them at all REN&Eacute; MAGRITTE, a surrealist artist, perfectly captured the idea of prosopagnosia, or face-blindness, in his painting “The Son of Man”. In the picture, an apple floats in front of a man's face, covering the features that would normally allow him to be recognised. To people with prosopagnosia, the instant someone leaves their sight the memory of that person's face is blank—or, at best, a palette of muddled features. Face-blindness can be likened to tone-deafness: the tone can be heard, or the face seen, but distinguishing between different tones or faces is nearly impossible. The effects of prosopagnosia can be so bad that people with severe cases cannot recognise their own parents or children. Understanding the face-recall mechanism in the brain would be a big step towards understanding this odd disorder. It might also throw light on human evolution, since the ability to recognise faces is more or less equal to the ability to recognise individuals, and that ability is the glue which holds societies together and which has enabled humanity to develop a complex culture unique in the animal kingdom. The question is whether this crucial ability has its own private brain mechanism, or whether it is simply one aspect of a general ability to recognise individual members of a particular class of objects. Let's face it A paper by Brad Duchaine and Ken Nakayama of Harvard University, which is to be published shortly in the Journal of Cognitive Neuroscience, uses face-blind volunteers to explore this question. In the study, Dr Duchaine and Dr Nakayama showed their seven face-blind subjects a series of images of cars, tools, guns, houses and landscapes, and also black-and-white pictures of faces without hair on their heads (prosopagnosiacs tend to use cues other than facial features to distinguish between people). Ten of these images were repeated during the cycle. The subjects were asked to indicate, as quickly as possible, whether each image they saw was new or repeated. If, the researchers reasoned, visual recognition is done by one type of brain process regardless of what is being recognised, then the face-blind subjects would show difficulty in recognising all repeated objects in the series, not just the faces. They found, however, that while none of their prosopagnosiac subjects could recognise the faces in the series well, they could distinguish between the other repeated pictures as easily as people without prosopagnosia could. That confirm‎s the idea that faces are handled differently in the brain from other objects.