A face-specific mechanism for recognising people in the brain?

Humans are amazingly skilled at recognising faces. A recent study suggests that the brain has a unique mechanism specialized for doing this. Exactly how faces are recognised has been debated among scientists, and there are two alternative hypotheses that try to explain this. The face-specific hypothesis suggests that the brain possess a unique mechanism for disentangling faces, whereas the expertise hypothesis proposes that the same mechanisms that allow us to recognise visual traits underpin face-recognition.

Scientists from Harvard University attempted to disentangle these hypotheses by performing an experiment with individuals with prosopagnosia, a cognitive disorder commonly refer to as face blindness that prevents people from recognising faces. First they generated computer-based objects called ‘greebles’, which were designed to mimic the way the brain recognises faces by varying some appendages that were arranged in a common configuration. Then they trained patients with face-blindness and control individuals to identify these objects, and after a period of training they compared how well they were at recognising them and at identifying faces.

The results showed that individuals with prosopagnosia were just as good at identifying different greebles as normal people, but were incapable of recognising faces. These results strongly suggest that the mechanisms that allows for face-recognition is face-specific, and not part of a broader mechanism.

However, leading author Constantin Rezlescu acknowledges that these results need further testing, as expertise acquired in laboratory conditions may not be equivalent to that acquired naturally. Nonetheless, interesting questions emerge, like how the brain recognizes identities, and how other traits, like voices, are also integrated.

DOI: 10.1073/pnas.1317125111

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