A forgotten but (perhaps) important experiment in colour vision.

Many years ago, in 1983, I published a paper on colour vision, in which I described an experiment that seemed to me to be important. Although the paper has been cited many times, the particular experiment I am referring to has never, to my knowledge, been quoted by anyone. In fact, even I had forgotten all about it until very recently, when someone made what seemed to me to be an inaccurate remark about colour opponency.

Colour opponency refers to the fact that there are three pairs of colours which have been described as those that “cannot live with each other, and yet cannot live without each other”. They are red-green, blue-yellow, and white black. For, as most people know, when we look at a green surface for a brief period of time and then transfer our gaze to a neutral, blank, screen the colour of the after image is red. A yellow surface will produce a blue after image and a white surface a black one.

One explanation of these opponent effects – the one most often repeated – is that they are due to adaptation in the retina. The explanation here is something like this: that a green surface reflects more green light, leading to the adaptation of the “green” or middle wave receptors. Thus adapted, the activity in the opponent “red” receptors holds sway. The result – we perceive red. The same explanation applies to other opponencies.

The experiment I described was derived from, and an extension, of the colour experiments of Edwin Land. Land had shown that a green surface which is part of a complex, multi-coloured, scene can be made to reflect more red light and yet still look green (though a darker shade of green). This is because the brain undertakes a somewhat complex operation to discount changes the wavelength composition of the light reflected from that surface. This makes sense. After all, a green leaf looks green when viewed at mid-day or when viewed at dawn and dusk (when it actually does reflect more of the long-wave or red light). If the perceived colour of the leaf were to change with every change in wavelength composition reflected from it, then the surface would no longer be identified through its colour.

It seemed to me interesting to take this one step further and get humans to look at a green surface that was part of a complex scene and get that green surface to reflect more red light (twice the amount of red than of green light). It still looked green. Now, by the traditional explanation, the after image should look green, because the “red” receptors, having adapted, would defer to the “green” receptors, which had not been as vigorously stimulated and hence had not adapted. Not a bit of it. The after image was red! I repeated this experiment with other colours and got the same general result. The after image is not related to the wavelength composition of the light reflected from a surface. Rather, it is strongly dependent upon the colour of the surface viewed. Since the colour of a surface, when part of a complex scene, is independent of the wavelength composition of the light reflected from it alone, it follows that the colour of the after image is also independent of the wavelength composition of the light reflected from that surface.

Hence the colour of the after image is constructed by the brain after the colour is constructed. It has nothing to do with retinal adaptation.

But no one has taken the slightest notice of this experiment and, as I said, even I forgot about it. That is a pity. It still seems to me to be an important experiment, but evidently no one shares my view.

Coco Chanel, Yves Saint Laurent and the brain's anxiety system

Something puzzles me about fashion design and the brain.

Coco Chanel was undoubtedly one of the greatest designers of the past century, if not the greatest. She liberated women from constraints and allowed them to be both comfortable and elegant. The classical Chanel suit looks good on women of all ages and sizes. More than any other design, it has stood the test of time.

Yves Saint Laurent took this a step further, and used fashion to symbolise the growing power and independence of women, and at the same time make them look good.

But fashion and elegance, it seems to me, have another and perhaps more important purpose – to feel good, something that Coco Chanel especially understood well. This presumably correlates with activity in some reward centre of the brain.

And here comes the puzzle. Chanel and Saint Laurent both used beautiful women for their designs and shows – one might even say “ideal” women, chosen for their grace, and beauty, and sex appeal. Such women, by definition, are “exceptional” in their appearance. Yet many women who pay a fortune to be dressed by couturiers such as these are not in the same league of beauty or appeal. So what is it that makes them spend so much money on clothes designed with “ideal” women in mind?

I suppose that donning such clothes makes them feel good by changing their image of themselves, which must involve a considerable nervous apparatus. I recently saw a woman dressed in the latest, expensive, fashion. Her general physiognomy suggested that she felt good and did not lack in self confidence. Yet to an external observer, the latest designs she was wearing were very ill suited. Never mind, she felt good in them – a subtle change must have occurred in her brain!

I was therefore interested to read a recent paper entitled “I am not as slim as that girl” by HC Friederich and others [Neuroimage, 37:674 (2007)], in which the authors asked female subjects to compare their own body shapes to that of “idealized” women shown and rate their level of anxiety as they viewed these pictures. It turned out that, in addition to brain areas concerned with body-shape processing, there were activations in brain areas whose activity correlates with anxiety, the activations in these areas being proportional to the declared level of anxiety.

This is interesting, but also surprising. I certainly could not tell from my observation of the lady referred to above that she was suffering from any anxiety, far from it. So, perhaps splashing all this money out on a Chanel suit or Saint Laurent trousers really works by reducing the activity in the anxiety centres in the brain. Clearly worth further study.

Heathrow’s Terminal 5 and the brain’s reward system

Those studying reward and punishment in animals and humans often use very simple methods, which turn out to be remarkably effective. In studies of reward and punishment, the subject is instructed to take some action. If the “correct” action (as determined by the experimenter) is taken, there is a small reward – in the form of a peanut or a sugar pellet or a reinforcing sound. If the “wrong” action is taken, a mild electric shock or a disturbing noise is applied. Perhaps as important is this: that when a “wrong” action is taken, often nothing happens – there is simply no reward. That is all. The absence of a reward is itself a punishment.

These are simple but important lessons that those designing public buildings such as airports might wish to learn. The entire design of Terminal 5 at Heathrow shows an abysmal ignorance of the brain’s reward system. Consider this: that when you enter the building, you are ushered to lifts, which have no call buttons. So you cannot even take an action, either rewarding or punishing. If a lift goes by without stopping (punishment), there is nothing you can do – like pressing a button and watching a light come on (reward).

The sign-posting is about the most inept you can imagine. When you arrive and try to make your way to Heathrow Express, there is one arrow pointing forward. You proceed down the hall until you get to the end, and find nothing (punishment). You turn back and, after some searching, find that it was on your left, but there is no filter arrow to indicate it (punishment). Once you get the right direction, a sign tells you that the quickest way to Heathrow Express is by the lift, not the escalator (reward – but read on). So you take the lift and go to the Heathrow Express hall only to find that there are no ticket machines and no ticket counter (punishment) or, if there is one, it is extremely well hidden (Recall that, as a punishment, you would have to pay more to buy your ticket on board the Heathrow Express). So now, you take the escalator back up (remember, lifts have no call buttons, at least on the outside) and go to the arrivals halls, where the automatic ticket machines are located, and then back down again.

This disgrace even permeates the BA lounge. If you follow the sign to access it, you are told to go back to the escalator, retrace your steps one floor down, where you will find the lounge located below. Once you get there, you are ushered upstairs again, where you end up where you started from! I have seen many bewildered passengers wondering what this is all about. The reason is simple. Apparently BAA wants you to visit the shops through this detour! That this is punishment is implied by the fact that premium passengers (those paying upwards of £5000 for a flight) are allowed in without having to retrace their steps, although one would have imagined that they might have more money to squander on shops. In fact, much of the internal architecture of the terminal – emphasizing space – is lost because it is cluttered with shops. Indeed, one gets the impression that the airport is more of a shopping mall than an airport, with passengers a nuisance to be tolerated provided they shop.

The huge new BA lounges are inviting at first. But then, if you want to go to the champagne bar and also have a nibble or two, you will find no food there (punishment). To get the food, you have to back-track some distance – greater or lesser depending on whether you want hot or cold snacks. The best of all is that there are no announcements (punishment) – not that there isn’t an intercom system. There is, but I suppose that they don’t want to be bothered with it. So you have to rely on the electronic notice boards. But these are not everywhere (punishment). There is none (punishment) in the champagne bar, where the tycoons and tycoonettes congregate. I saw one tycoonette who was outraged when informed casually by another passenger that there are no announcements, and she had to walk a good distance to find a board which announced that her flight to Istanbul was closing – in a satellite building which takes some 10 minutes to get to. The poor old dear, she had to gulp her champagne quickly and rush cursing to the nearest exit.

We are told that this is the biggest free standing building in Europe, perhaps the world. You would imagine that such a building – a gateway to the world – would have an inviting and aesthetically pleasing entrance, which could be viewed and admired. Forget it! The front is covered by concrete buildings and fly-overs to deliver those lucky enough or rich enough to use taxis and limousines (at about £80 for a taxi ride to central London, this makes even Heathrow Express – the most expensive railway route in the world – seem reasonable). The only way you can admire the building – if indeed you want to after these punishing experiences – is from the runway, providing you are sitting in the correct position in the plane.

It seems to me, then, that BAA and architects could learn a thing or two by making a greater effort to study the reward and punishment systems of the brain. There is even an Academy of Neuroscience for Architecture, founded by John Eberhard, from which they could get some help. There are of course some architects who do this already. Philippe Rahm, in Paris, actually studies papers in neuroscience and incorporates the lessons he derives into his designs. He sets a good example.

This of course will take time. Meanwhile, Heathrow remains the worst airport in the developed world (though you would be forgiven to think that you have arrived in the non-developed world). It is a puzzle that so many want to use it – with its long delays, its inept and rude staff, its designs that are wholly removed from human needs, one would have thought that most would by now have abandoned it or at least protested vigorously enough for something to be done. But I suppose actually getting to London (or getting away from it) must be a bigger reward, worth all these punishments. Terminal 5 is bad, very bad. But it could be worse. You could end up in Terminal 3 or Terminal 4! There are clamours for the monopoly of BAA over British airports to be broken up. I would advocate going a step further – break up the monopoly over Heathrow, and let different companies run the different terminals. That will introduce more competition, which will be a good thing.