Even Odder Perceptions

Richard L. Gregory

• Publisher: Routledge
• Year: 2017
• ISBN:
  9781315516035
• Edition: 1
• Topic: Psychology
• Subtopic: History & Theory in Psychology
• Index: Psychology

Why did Newton struggle for thirty years to make gold by alchemy – and then become Master of the Mint? Why do we blush? Why do we have illusions?

In this collection of essays, originally published in 1994, Richard Gregory once again delights and tantalizes with tales of his childhood, his family and friends, the famous and the infamous, and weaves them into a rich pattern to illuminate scientific principles and puzzles. If you can put the book down, each essay is complete on its own, but they are united by the magic of human perception. From seeing and hearing to feeling and believing, from the shape of traffic signs to knowledge of quantum mechanics, all our interactions with the outside world are mediated by perception.

Our knowledge is further distilled by the machines which help our own biological mechanisms, like microscopes and telescopes, electric light, and even more powerfully by computer technology. But if the natural structures of perception can affect our interpretation of the world, how much more dramatically might science education and tools of information technology enhance – though sometimes mislead – our perception of reality? Even Odder Perceptions may not have all the answers, but it certainly poses more questions.

1
Traffic Lights

One of my earliest memories is of an elderly policeman in tears. He was standing by a lone traffic light at a simple crossing in a quiet English village. My father, who was driving, stopped and asked the policeman what was the matter. It turned out that he had worked all his life at this crossing, directing the occasional car or van: now he was replaced by a traffic light. All that he had achieved through forty years in wet and cold and heat was now done by mindless red and green lights.

This was my introduction to poignancy.

When my children were small, sometimes we would play the game of blowing out the red to make it change to green. Of course, the glass of the car’s window-screen was in the way, but this was magic. It always worked. Quite soon the red would give way to green – and we were off. By this magic the children experienced with the traffic lights the kind of power to make things start or stop that the policeman had lost with the coming of the lights. Looking back on his life on the crossing, the new lights told him he had been an automaton all those years, for now a rotating switch in a box had replaced his brain. Thirty years later the children experienced the power the policeman had lost, as the automatic traffic lights seemed to respond to their will. Perhaps both were illusions.

However this may be, we respond to traffic lights as absolute authorities. This is so whether they are time-sequenced or switched from sensory pads in the road, responding almost intelligently to traffic. We are sometimes annoyed by having to wait, and just occasionally we start to doubt. Has it gone wrong? Is it stuck? This is an odd decision that we make – with possible death the outcome – for how do we know when the light is supposed to change? We edge out very slowly with extreme caution, hoping no-one sees us, palpitating with guilt and nameless dread, as we violate the Law of the Light. Then, safe, we race away from the confrontation with fate – looking back to see the red change to green as it pursues us with guilt.

Waiting for red to change to green on a clear open road is an even odder experience. It is perfectly obvious that nothing is coming so it is perfectly safe to drive on, yet we are inhibited by the extremely strong rule that red means Stop. This is the most strongly held law in modern life, for we all accept that its universal acceptance is life-saving. The red light is the last Kantian Categorical Imperative.

Would it be imperative if traffic lights were human? Imagine a policeman on traffic duty, holding one up for several minutes with absolutely nothing in sight. One would soon assume that his body is not obeying his mind; or that his mind is elsewhere. It would be quite frightening, for one would not know quite what to think. Is he a dummy? Dead? Trying an experiment? There are no such doubts or thoughts for automatic lights, and on balance they are completely fair. Even when in a great hurry one accepts the situation; one accepts the imperative as inevitable. Preference for machine-made over human-made decisions, like most things, goes back to the Greeks. The Athenians of the fourth century BC used an automatic device of randomised tickets in slots, the kleroterion (Brumbaugh 1918, p. 66), for selecting juries. Jury service was an onerous duty, involving days of boredom sitting under the sun. The machine was preferred to human officials and even to the gods, who might be biased. Similarly, we accept the delay at automatic traffic lights because we know they are scrupulously fair and, being totally unintelligent though meaningful, they would not understand that we, or other contending drivers, are late for train or plane.

As for most human laws, laws of the lights are somewhat different in different countries. The universal international pedestrian-traffic war has various rules for the amber temporary truce between red and green. There are even differences between states of America as the amber has different meanings in Boston, New York and California. And within Britain there are different ambers: most crossings have a fixed amber period, cunningly phased with red and green delays; in others amber flashes, allowing a temporary contract between driver and pedestrians with human sign language and the making of faces. It is in the uncertain duration and various kinds of amber period that the driver’s decision to stop or continue must be made. (There was a steamy novel called Forever Amber. This is totally irrelevant.)

All those lights switching on and off must be expensive. Is the amber really necessary? There is a story that they tried to get rid of amber lights in Chicago, which would mean quite a saving in bulbs. They went further: why have separate light bulbs for the red and green lights? This was a clever idea. It depends on the fact that a single bulb in a square box with four glasses – two reds opposite each other, two greens opposite each other – will give, let’s say north-south red and east-west green from just one bulb. A second identical box, immediately below but rotated through ninety degrees, will give the reverse: north-south green lights and east-west red lights. So, by switching on the bulbs, with only one on at a time, the lights will change from red to green and green to red for all directions. Brilliant! But there was a snag. Normally, red is always on top but with this system, though red is on top for one direction, red is below the green for the other direction. This may not matter for people with normal colour vision; but colour-blind people (who confuse red and green) can no longer use position to see which is red and which is green. How much position is used by colour-blind people with red-always-on-top is an open question, but apparently it was claimed that colour-blind people in the Chicago experiment had so many accidents, as red was not always on top, that this clever scheme was abandoned.

Years ago traffic lights were simple and unambiguous. Red meant Stop – green meant Go. But now this is different. In Britain it is common to see a red with a green arrow immediately below it. So we have red and green at the same time! The imperative red is countermanded by the permissive green arrow. Now the sign is a mumbled StopGoStopGo. Ouch! As the green arrow counters what used to be the universally imperative red for straight ahead, it implies that we have to interpret what the red forbids and what it allows. It allows straight-on – which is normally forbidden by the red – and it forbids turning right or left – which are not explicitly signalled.

Presumably this system is based on research, but it certainly seems counter-intuitive and to flout several quite basic principles. The situation is made even worse by the placing of the lights to the side of the crossings, rather than suspended above as in many European countries and America (though this also has its problems).

Is there some better way? We have green, but not red arrows on traffic lights. Why don’t we have red arrows for Don’t go? It might be objected that an arrow should always mean Go. But, as things are, there is not this consistency in British road signs, as there are arrows with cancelling cross-lines meaning Don’t turn left, or Don’t turn right. So why not red arrow traffic lights, meaning Don’t go – straight, or left, or right, as the red arrow tells you? Then red is always Stop and green is always Go.

If colour-blind people confused the red and green arrows they could be given special shapes; or, as the existing road sign cancelled-arrows have now, cross-lines. Europe has special arrows made of dots.

Quite apart from countermanding green, how sacrosanct is red? Is it ever justified to ‘beat the lights’? A perpetual bother of driving is that although one can see what is happening very well in front and one can take avoiding action to what is in front, it is very different behind. Even with the best mirrors, one entirely depends on the judgment of another driver to avoid collision from the rear. If he or she is coming up fast behind as the lights are about to change, what should one do at this critical moment? It may be safer to accelerate as the red appears. In Bristol (where this is written) TV cameras have been set up at some crossings to look for drivers beating the lights. A sharp increase in minor collisions from the rear has been observed at these lights. As the cameras are visible, drivers know they are being watched and can be traced from their number plates, so presumably normal on-the-turn-to-red behaviour is upset – drivers are being too punctilious.

Some of the British road signs are mandatory, others obligatory. The distinction is clearly important. It is represented not by the sign but by its background. An arrow-sign is mandatory on a circular background, and advisory on a square background. Not realizing this when it was introduced some years ago – the shape of a background is not a usual sign – I violated a mandatory Don’t turn left arrow in London and was stopped by a policeman. When I asked why this was a violation, he explained that the sign was mandatory but he did not seem to know why, except that he had been told to stop drivers turning left at this point. He didn’t seem to appreciate the distinction between a round or square background any better than I did. A week later, a summons arrived for illegally turning left against a mandatory arrow. Over the next few days I asked six policemen the difference between round and square backgrounds. None knew the difference, or that there was a difference. Armed with this, I phoned the local chief of police and told him the result of my little survey. He cancelled the summons. In my experience the police are fair and reasonable. Who would expect the shape of the background to change the meaning of a sign?

Whether the system of traffic lights is based on research is a moot question, but certainly there is extensive research on driver behaviour and accidents at lights. Allsop, Brown, Groeger and Robertson (1990) report that 20,000 people are injured at signalled-controlled road junctions each year in Britain. Considering that lights are placed at crossings to make them safer this seems a high figure, though it is small compared with the umpteen millions of crossings made by cars and pedestrians every year. It is reported (Allsop et al 1990, citing Olson and Sivak 1986) that in a ‘surprise’ situation, movement time from accelerator to brake is in the range 280–780 ms (median 400 ms) for younger drivers (18–40) years) and, surprisingly less, is 220–480 ms (median 350 ms) for older (50–84) drivers. When people were alerted with a warning, these times become 200 ms and 220 ms respectively. Perception times to a sudden red light are: 420–1020 ms (median 750 ms) for younger, and 630–1030 ms (median 750 ms) for older drivers. When alerted, both age groups have a median of 500 ms. Just how, and with what reliability, decisions are made in the ‘uncertainty period’ before the red changes has both theoretical and practical significance. It is not ‘merely academic’.

Driving requires fine judgment. As for all symbols, traffic lights and road signs need to be interpreted with intelligent appreciation of context and other drivers’ intentions, with prediction and evaluations of possible outcomes. Much of this highly complex, ever-changing decision making – remarkably – is below the level of conscious awareness. Indeed, becoming analytically aware can make us dither, creating uncertainty and confusion. It is amazing that almost anyone can drive reasonably safely – possibly because the cortex is not much involved! – though the task is difficult and inherently dangerous.

Perhaps necessarily, the lights and the law require – yet also penalise – intelligence.

References

Allsop, R.E., Brown, I.D., Groeger, F.A. and Robertson, S.A. (1990) Approaches to modelling driver behaviour at actual and simulated traffic signals, Final report by the Transport Studies Group and MRC Applied Psychology Unit Cambridge to the Transport and Road Research Laboratory on contract 9834/35. (UCL Reference ECW3.)

Brumbaugh, Robert S. (1918) Ancient Greek Gadgets and Machines (Westport, Connecticut: Greenwood Press).

Olson, P.L. and Sivak, M. (1986) Terception-response time to unexpected roadway hazards’, Human Factors 28(1), 91–6.

2
The Case of the Sugared Almonds

Some tiny events stay in one’s memory as gems to be treasured, every now and again to be re-examined. This is a very special private gem, not really to be revealed. Please treat it as such.

Just after we married we dined in a very grand restaurant in Scotland. It was one of those places with too much of everything: over-large dazzling white tablecloths; so many waiters they were faceless smiles; massive silver so polished it was invisible, reflecting a world of secure assumptions we hardly understood. There were even odder reflections from the too-many gilt mirrors, Escher-worlds away.

My wife was in a dreamy mood. What were her thoughts?

With the coffee, an absolutely enormous bowl full of sugared almonds was placed on our table. There must have been at least a hundred almonds, lying there to be selected, each identical to its sugary companions. To my astonishment – lasting to this day, years later – my young wife picked up the huge bowl and poured practically all the sugared almonds into her handbag.

’Is that right?’ I asked.

’Of course,’ she answered.

The rights and wrongs of this remained a topic of debate for years. Here is the issue:

She: If the sugared almonds are provided – and they were put on our table to be taken by us and no-one else – why shouldn’t we have any number of them?

Me: Too many are deliberately provided, so that we have the luxury and freedom of choice.

She: But I made my choice – I took lots of almonds.

Me: But you aren’t supposed to take so many.

She: Then where is the freedom of choice? What’s the point of being offered lots of them, if one can’t actually take lots of them?

Me: Um – well, you see – because in a place like this one has the feeling of opulence and that one has the best of everything – which makes one feel special.

She: But what is so special, if we can’t have more than two or three almonds?

Me: Well – you could – only you shouldn’t have put them in your handbag!

She: Why not – I couldn’t eat any more now.

Me: Well – you see – that’s the point.

Unfortunately she didn’t see this point. I never was able to explain it effectively, to her or to myself.

Just what is the point?