Nelson – face recognition

Let me first talk a little bit about the work we’ve done on face recognition. The first question we should ask is so why would you want to understand how the ability to recognize faces develops? Prior to the time when infants develop language most communication is non-verbal. So that means really the first one to two years of life a lot of communication between a baby and his or her primary care giver or anyone else is non-verbal. So we need to understand how it is babies read faces, both at the superficial level of “who is that?” to the more fine level such as “how does that person feel right now?”  And so we put a lot of effort into understanding that development as well as what are the neural systems, that is, what are the parts of the brain that are developing that facilitate those abilities to recognize faces and facial expressions of emotion.  

The other part to it is to understand how experience influences that process. Some people think that this is such a fundamental ability that there’s an area of the brain dedicated to recognizing faces and it’s there at birth. We take a different view which is that we think that there’s an area of the brain that has the potential to become specialized for recognizing faces. But it’s only by seeing faces that that actually happens. And very good evidence for that actually doesn’t come from this lab but it comes from Daphne Marro’s lab at McMaster University. Daphne Marro and her colleagues have looked at a sample of children who were born with dense cataracts. These are opacities over the eye and at a certain age, usually a few months after birth, have the cataracts removed. And as a rule, they have a wonderful outcome. Their visual acuity improves dramatically, they see quite well. But it does turn out they still show subtle deficits in recognizing faces.  

So those data, coupled with our own data where we record brain activity, collectively says that experience really does thrive that ability. And I’ll give you an example. In the paper two former students of mine published last year, Michelle DeHawn, who was going to McMaster as an undergraduate and then came here to graduate school and now is — University College, London and Olivia Pascales who is from France but now works in England and did part of his dissertation here, showed that, predicted rather, that early in development infants have a very broadly tuned perceptual apparatus for recognizing faces. So what that means is that they should be quite good at recognizing and discriminating all sorts of faces but as they get more experienced with just human faces they would lose that ability.  

So we predicted that babies would, young babies would be as good at discriminating two monkey faces as they would human faces. Now anyone who has seen monkeys, unless you work with monkeys, know that they all look alike. And at six months, they found six-month olds were as good at discriminating two monkeys as they were two humans. But by nine months they were like adults. They could not do two monkey faces anymore. And so the logic behind that is that’s because by nine months infants have had three months more experience seeing human faces and they are gradually losing the ability to discriminate monkey faces. So that’s another way to demonstrate that experience is important.