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  • Harry was a friendly young man, 32, married with a wife and children.

  • The only problem was that Harry couldn't actually recognize his wife or children by looking at their faces.

  • His wife, for example, had to identify herself to Harry by wearing conspicuous articles of clothing, like a big red hat.

  • By taking one quick look at something like... my face... you can tell my age, gender, race, where I'm looking and even my mood.

  • And if you've met me before, hello, you generally recognize me in a fraction of a second.

  • We have this amazing ability to recognize faces.

  • There's even a dedicated area in our brains for it, but we hardly ever stop to think just how amazing this really is.

  • For all the new faces we see, our brains figure out how different it is from our perception of an average face.

  • This is an average of all of the faces you've encountered before.

  • Our brains reduce the facial features, like eyes or lips, to a point and what we remember is just the distance and direction of that point from the centre.

  • This is called face-space, not like the FaceSpace the Oatmeal invented but a vector based mathematical model of face perception proposed by researchers in the 80s.

  • It allows us to remember a huge amount of faces, because what we store in our memory is this code, rather than having a photographic memory for faces as a whole.

  • Because of this tendency to construct an "average face" from all of ones that we see, we're more likely to remember distinctive faces,

  • like Gollum's huge eyes or Mr. Spock's pointy ears.

  • As for people we already know, like our friends, family and even celebrities, something interesting happens inside our brain when we see their faces.

  • Researchers recorded lots of single neurons, which are so incredibly tiny, in patients suffering from epileptic seizures who had electrodes implanted within their skull.

  • They found that single neurons fired only when subjects were shown pictures of Jennifer Aniston, or Halle Berry, compared other faces or objects they didn't recognize.

  • Your neurons aren't lightening up because you're jealous of Jen's hair or love her chin, it's simply because you recognize her.

  • This activation of your neurons happens for your friends and families too, it's quite appropriately called "the grandmother cell".

  • Some researchers question the existence of such a neuron, but perhaps the neurons firing is our way of retrieving our face space memory.

  • Sadly there are times when grandmother won't be there to help.

  • There are some people, just like Harry, who don't recognize any faces, ever.

  • People who suffer from this condition, face blindness or prosopagnosia, have a warped face space.

  • Most of the time it's due to brain damage in facial recognition areas.

  • Harry actually sustained head injuries from a car crash, other people are born with it.

  • It's like people suffering from this condition just can't join the dots,

  • some face blind people will only recognize those they see very often, some won't recognize anyone at all.

  • So things like Facebook are even better at identifying you than some people are.

  • And facial recognition technology actually uses the face-space principles to work.

  • This technology identifies you, or me,

  • by measuring things like the distance between your eyes, the width of your nose, the shape of your cheekbones and the length of your jaw line.

  • In other words, your faceprint.

  • While most of our brains do this intuitively,

  • I hope there's some way for facial recognition technology to help face blind people recognize their wife or children in years to come.

  • So the next time you just can't remember a person's name, be thankful that you can recognize their face.

  • And that you don't have to wear this for your significant other to recognize you.

  • If you haven't already, subscribe to BrainCraft! I have a new video out every other week.

Harry was a friendly young man, 32, married with a wife and children.

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