How do we read a face?

 The common idea of the human face as revelatory of its owner’s type and character was taken up by 19^th century psychologists and regarded as especially valuable in the identity of criminal, psychopathic and neurotic personalities. Theorists and experimentalists confidently published physiognomic field guides and photography was quickly enlisted to present categorical arrays of facial types. Clinicians and policemen alike used these ‘anthropometric’ albums to help identify the latent tendencies of patients and suspects. As mug shots and passports attest, it is not difficult to make the most intelligent , harmless and sane of us look irremediably wicked or mad.

 Research shows that in judging identity or personal/physical similarity we tend to rely more heavily on information from the left side of someone’s face (as e see it i.e. their right side). You can test this by viewing the ‘real’ face in a mirror; you will most likely see the other composite as more similar.

Why is this so? It may be that more personal identity information is contained on the right side of the face (left side as we see it) – in fact most faces are wider on the right side – and that we attend more to that left side, but research on where we focus most when looking at a face had not been conclusive. A different account emphasizes that in most people their right hemisphere of the brain seems more specialized for facial recognition. If you focus on the center of a face without moving your eyes, the neural pathways from the eyes project what is to the left of your visual field to the right hemisphere first (and vice versa), and that side of the face would reach the area specialized for face recognition more quickly and dominate in recognition.  But in fact we don’t normally look only at the center of a face; our eyes move about and information from each side reaches both cerebral hemispheres within moments.

 Perceptual asymmetries extend to our emotional responses. The right side of the brain is thought to dominate in our analysis of emotion and our expression of feelings. One might think that this would ensure that we also rely more on the right side of other people’s faces (the left from our viewpoint) when judging their emotion. But if the right hemisphere has greater control over emotional expression, then because our right brain controls our left side, it must be the left side of our face that expresses it more. And when we look at the left side of a face we are looking of course at its owner’s right side, in which case it wouldn’t make sense to rely on it to judge emotions. Research is inconclusive on this issue and there is as yet no consensus on the explanation (s) for asymmetries in face perception.