A face, a voice…a person

The processes of the visual recognition of objects reserve a privileged place for the identification of faces. In a recent article published in Consciousness and Cognition, Professor Serge Brédart and Catherine Barsics, of the University of Liège’s Cognitive Psychology Unit, have confirmed the superiority of identifying a person through their face in recalling episodic and semantic information about them.

visagesEven if they occur in a fraction of a second, the processes of the visual recognition of objects requires the putting to work of extremely complex procedures, of which one of the main ones consists of discarding contextual elements and details concerning point of view which warp our perception of the reality of the object in itself – the play of shadow and light, the influence of the viewing angle, the distance at which the observer is situated, etc.

In addition, there is recognition and then there is recognition. If it is often enough to do no more than stack an object in a semantic category (‘Look out, a car!’), it is sometimes paramount to be able to identify in a precise manner a particular example within that category. This is a crucial operation if ever there was one for faces (Nicolas Sarkozy is not Jacques Chirac) and for words (the term ‘soap’ is in no way the equivalent of the term ‘gardening’), but also for certain well determined objects, such as ‘my’ house or ‘your’ bicycle.

We have in fact a very special skill to discriminate between faces, and this remarkable expertise has not escaped the attention of researchers.  They have even come round to believing that there exist specific mechanisms assigned to the processing of faces which were subtended by specialised brain regions. Today this idea is at the centre of a vast debate. In effect, an alternative hypothesis would be the existence of specific mechanisms, not focused solely on faces, thanks to which an individual would be able to identify unique objects within a given category within which the individual has forged some expertise.

Without being decisive a particular phenomenon nevertheless pleads in favour of the first hypothesis: ‘the disproportionate effect of inversion,’ brought to light in 1969 by Robert Yin of the Massachusetts Institute of Technology, at Cambridge. The experiment consists of submitting to individuals an image reversed in the vertical direction. What do we observe? That their recognition performance is affected. But, and this is the key element, their scores are all the more worse when the stimulus is the image of a face, whilst, when they are the right way up, faces are more easily recognised than other stimuli. And this has led to a backing up of the idea of that there exist mechanisms which are specific to the perceptive processing of faces in normal conditions.

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