Wednesday, February 02, 2005

Human: Facial Recognition

One of the most outstanding abilities of the human animal is the ability to recognise faces, or even just parts of faces. Facial recognition is something we mainly do unconsciously and it usually takes just a fraction of a second. But why is it such an amazing talent?

If you count up the number of friends, family, colleagues and acquaintances that you know (and recognise with great ease) you would probably come up with hundreds. That's a lot of faces to remember. But wait, that's by no means all of them. How many different people that you don't know but see on a regular basis (on the TV, in magazines etc) whose faces you also know well? Hundreds more? Thousands? And it's not just a case of recognition, this skill allows you to identify the individual that owns that face.

Let's say that the average person in the developed world (i.e. has access to television and other media on a regular basis) can recognise three thousand different people with relative ease (I tend to think that number is probably higher). I can't think of any other animal in the world that lives in a community of that size where there is a need to be able to identify individuals. Other social animals, such as chimps or wolves, can do it, but none as well as we do.

And that's not the extent of the ability, either. How many times have you watched shows like A Question Of Sport, where you have to identify someone from a few oblique shots of different parts of their faces, or a picture that is made up of the eyes from one person, the mouth from another etc, and been able to do it? What about passing an old school-friend, who you haven't seen since you were 16, in the street and knowing who they are despite them having aged considerably? This is where the pattern-matching side of the ability comes into play.

Instead of storing the whole face in your memory, it seems the mind stores each bit (eyes, mouth, nose and so on) separately but linked together so that if you see a pair of eyes that you know, you can reconstruct the rest of the face and therefore identify who they belong to. All that done in a flash. It's pretty amazing, wouldn't you agree?

An extension of the talent is being able to recognise a friend walking towards you long before your eyes are able to pick out individual facial features. Height, weight, hair colour, the way they walk plus a whole host of other factors allow you to identify them.

As a highly social animal, this ability is key to us being able to get along. There are people who lack this ability and only through a huge amount of exposure to a face (or linking it to a strong emotion) are the able to recognise it. For them, it is exceedingly difficult to operate 'normally'.

Facial recognition is a talent we rarely think about and yet do all the time. We would be lost without it.

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