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An argument in favour of animal experimentation


How do we see?
Francis Crick Scientist
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Well I’m interested in… in how we see things. When I say this to people over the dinner table or whatever it may be, there’s usually a pause because they can’t think what it is that one wants to know, and the reason that they feel that way is that when they see, it’s simply so effortless, they open their eyes, they look around, they see the world, as we say, in glorious technicolour and what is the problem? Well, it turns out when you look into the processes that have to go on in the brain to enable you to see, they are much more complicated. So, people’s idea about what constitutes seeing is totally over-simplified, one would almost say wrong, I think. Now, the way you can show this is, is you show various visual illusions which makes them realise that seeing isn’t a simple process and that seeing is a constructive process; your brain has to construct from the information coming into your two eyes, this just two-dimensional projection of some aspects of the visual world onto your eyes, it has to construct this three-dimensional picture that you have in some sense in your brain, although people argue what sense it may be, how do you construct that? And that’s a complicated process which you can’t easily do in a machine. People have been trying to make machines to do machine vision and the more they try to do it, the more difficult they find the problems are. When you look inside the brain you don’t find a simple bit of apparatus – seeing is not done just in your eyes. The… the signals go through a relay station to the back of your head and then through a series of… of stages going forward and those are very complicated, much more complicated than we even realised 20 or 30 years ago. And many different parts of the brain do different things. One bit of the brain appears to be mainly interested in colour and shape, another bit of the brain appears to be interested in movement. And you know this is the case because you can have people with brain damage, for example, who only see in black and white, they can’t see colour and there's one person with… in Germany, a patient with brain damage, who can’t see movement. She can see things all right, it’s like seeing the hour hand of a clock, but she doesn’t see it move. So it’s very threatening if she goes out into the street because she can’t see the cars moving. When she looks again, the car’s in a different place. When she pours a cup of tea, all she sees is a gleaming thing of liquid, she doesn’t see the… the tea rising in the cup and often it will spill over before she realises it’s full. Now, that isn’t the way people think about the way they see. They think they just see like that. But it isn’t like that. So we have to… you have to understand the problem of seeing. You have to understand, first of all, all the things that visual psychologists have shown, the very funny phenomena they’ve uncovered on the one hand, then you have to understand essentially what is known about the brain, usually about the monkey’s brain because we can’t do these… many of these experiments on people. Monkey’s visual system is probably fairly similar to ours, and then you try and put these together in some way to ask what constitutes seeing. But it turns out that if you put the animal under an anaesthetic, much of the reaction that goes on its brain is somewhat similar to when it's awake, so the actual awareness of seeing must depend in some way on some difference between when the animal is awake and when it’s under this anaesthetic and we don’t know what that difference is; whether it’s different cells firing or cells firing in different ways or some combination of those two, whether it involves some very special form of short-term memory or whatever. And how you get an integrated picture from all these neurons… all these nerve cells firing away is also a mystery. So those are the things we want to understand.

The late Francis Crick, one of Britain's most famous scientists, won the Nobel Prize in Physiology or Medicine in 1962. He is best known for his discovery, jointly with James Watson and Maurice Wilkins, of the double helix structure of DNA, though he also made important contributions in understanding the genetic code and was exploring the basis of consciousness in the years leading up to his death in 2004.

Listeners: Christopher Sykes

Christopher Sykes is an independent documentary producer who has made a number of films about science and scientists for BBC TV, Channel Four, and PBS.

Tags: Germany

Duration: 4 minutes, 3 seconds

Date story recorded: 1993

Date story went live: 08 January 2010