The Puzzle of Left-Handedness (11 page)

14

The Power of Small Differences

In the main, living conditions in the army used to be abominable: treatment was appalling and remuneration paltry. Given half a chance, almost everyone would try to avoid military service. In the period when lots were drawn this was not particularly hard, as long as you had enough money. You simply hired an impoverished replacement. The barracks were full of men too poor or too stupid to have found a way out, in many cases uneducated peasants who had never been more than a few kilometres from home. Conscripts could barely be taught even the simplest exercises, since most were unable to tell right from left and therefore had no idea how to put their best foot forward. There was one effective solution to the problem: a tuft of hay was placed in a recruit’s left boot and in the right a tuft of straw, materials with which all young country lads were familiar. The sergeant no longer shouted ‘left – right’ but instead ‘hay – straw’. In no time this approach transformed a motley bunch of blundering young men into a shipshape platoon on the march.

It’s such a good story that, to quote Ethel Portnoy, it must be a monkey sandwich, in other words a modern legend, a story everyone has heard but no one has witnessed and for which no one can provide a precise date or location. Nevertheless, the anecdote has spread far and wide. The Dutch version usually makes them soldiers in Belgium or the rural province of Limburg, the English tend to enjoy telling theirs as a tale about recruits from the Scottish Highlands, in America it features the tsarist armies of Russia, and in France the bumpkin soldiers are Corsicans or units commanded by the German Emperor. As with many such legends, there’s at least a grain of truth in it: people do tend to get their left and right mixed up, whereas they don’t have the slightest trouble telling other opposites apart, such as top and bottom.

The tricky left–right distinction is nevertheless crucial in many fields of life where we might least expect to encounter it. Of course everyone knows that left and right are important in traffic and in reading and writing, but there are many other ways in which they have an important if subtle part to play in our perception, interpretation and experience of the world around us.

Some brain researchers claim that thoughts and abstract concepts are a kind of mental simulacrum of bodily experiences. This hypothesis, known as embodied cognition, is less peculiar than it may seem. Behind it lies the idea that the only stimuli to reach the brain from outside are signals from the body, and some of those signals have their origins within the body. This certainly holds true for all kinds of information about the internal condition of body parts. Other stimuli do ultimately have external origins, but no direct contact is possible between the brain and the outside world. Instead, external events first stimulate one of our senses, which in turn sends a signal to the brain. The brain can experience only corporeal events, so what does it ultimately use as the building blocks for thoughts and concepts that have nothing to do with the body? Exactly. Those same bodily experiences. There’s nothing else available. In which case, the adherents of this line of reasoning argue, people with bodies that are constructed in a different way must think differently about certain things.

In 2009 Daniel Casasanto, of the same Max Planck Institute where Chris Seed had given his piano recital a decade earlier, found indications that this is indeed the case. In a series of tests it turned out that right-handers associate the space to the right of them with positive values such as ‘good’, ‘pleasant’ and ‘successful’ more readily than the space to their left. With left-handers precisely the opposite applies. It’s as if the preference for one hand over the other radiates out into the vicinity of that hand. This means for example that the same portrait photo, when placed on a table to the right of a right-hander, will be seen in a more positive light than when it happens to be placed on the other side. It may even mean that when an employer looks at a list of brief descriptions of job applicants that has been laid out in two columns, those in the column on the same side as his or her preferred hand will be judged more favourably. If this turns out to be true, then perhaps elections, selection procedures and recruitment are even less rational processes than we already feared. It seems there isn’t an awful lot we can do about that.

There are other ways too in which the relationship between left and right determines our take on reality. We like symmetry, a balance between left and right. In the environment of our daily lives we see this clearly enough. Chairs, tables and most of the other objects we use tend to be symmetrical. We place an equal number of chairs on either side of a dining table, directly opposite each other, since the whole set-up looks messy otherwise. This doesn’t mean we can’t appreciate asymmetry in furniture and utensils. We’re delighted if an accent breaks up the symmetry and by doing so emphasizes it – for example if we place the tablecloth at a carefully calculated slant and the vase of flowers deliberately off-centre. But asymmetry generally shouldn’t be taken any further than this. Asymmetrical furniture is strictly for arty-farty people eager to demonstrate how eccentric and non-conformist they are. An asymmetrical espresso machine is an example of radical design, something for the connoisseur who wants to show he’s averse to bourgeois consumerism and therefore chooses products with an industrial look, machines whose beauty does not rely on the crude satisfaction of our desire for symmetry but instead on functionality. Beauty that arises out of a natural disregard for considerations of beauty on the part of engineers, who are fixated on utility – that’s the kind of asymmetry we find stimulating.

It’s different of course with images that, rather than presenting functional items, depict events, situations or scenes from nature. A landscape or setting is rarely symmetrical, yet even here left–right symmetry has an effect. In contrast to the pairs top–bottom and back–front, symmetry between left and right produces a sense of balance and calm. One obvious example is the deliberate, overt symmetry of the classical, artificially clipped and trimmed French palace garden. In a more subtle, more concealed way, the English version of large-scale formal planting, the landscape garden, derives much of its attraction from symmetry. It’s this that gives the artificial landscape its aura of cosiness and safety, while carefully positioned asymmetrical elements help it to avoid the static dullness that attaches to the French style. Asymmetries create tension and unease, accompanied by a sense of dynamism. The panorama of a formal garden in some sense creates a story, which you read by looking around. A French palace garden is like a tiled wall, featuring endless repetition.

Differences between what we see to the left and to the right affect, almost imperceptibly but to a significant degree, what we see in a painting or diagram, on television, or on a cinema screen or computer monitor. Artists and designers take due account of this, even without being aware of it. They have to, because the distinction between left and right has an impact on our perception at every imaginable level. It’s an unavoidable aspect of how the natural world appears to us, and of the physical architecture of our visual faculties. The influence of cultural aspects such as the direction in which we write makes itself felt too, as does the fact that the vast majority of painters are right-handed. Nevertheless, we should not forget that our ability knowingly to distinguish between left and right is in itself quite remarkable.

15

How Freud Found his Right Side and Pooh Didn’t

In
The House At Pooh Corner
, A. A. Milne describes Winnie the Pooh failing to learn to tell his left from his right: ‘Pooh looked at his two paws. He knew that one of them was the right, and he knew that when you had decided which one of them was the right, then the other one was the left, but he never could remember how to begin.’

It’s the same as the problem we encountered in the illiterate recruits with their hay and straw, and something that children find harder than adults. Sigmund Freud, founder of psychoanalysis, vividly remembered how he had thought of a trick when he was a child slightly older than Christopher Robin: he inconspicuously pretended to write something down. The hand that automatically started to move must be his right, so then he knew, for a while at least, which side was his left. Innumerable children have thought up solutions along these lines, sometimes guided by a birthmark on one hand, a bracelet or some other clue.

Although adults find it a good deal easier to avoid confusing their left with their right, they’re by no means perfect at it. A great many motorists have unthinkingly turned right when asked to turn left. Computer programmers know only too well how easy it is accidentally to confuse the symbols ‘<’ (smaller than) and ‘>’ (larger than) in lines of programming and how difficult it can be to track down this simple error. Unpractised writers may reverse the occasional letter; in fact, this happens quite regularly when texts are written in giant script, as on notice boards listing the day’s special offers at a butcher’s or greengrocer’s shop. It seems that when a sign-dauber has those big letters right under his nose he can lose track of what he’s doing.

As long as we have a clear, obvious reference point, such as Freud’s writing hand, we’re capable of overcoming any confusion, but in situations lacking such indicators we have more difficulty. Which, for example, is the left side of a stage? It depends whether you’re looking from the stalls or from on stage. We need to make arrangements that will ensure instructions like ‘enters stage left’ are open to only one interpretation. The French have a neat mnemonic. Just as on board ship right is starboard and left is port, the French stage has its own names for right and left. Seen from the auditorium, the left side is called the
jardin
, the garden side, and the right the
cour
, the courtyard side. Spectators can remember which is which by thinking of the initials for
Jésus Christ
: the J for
jardin
is on the left and the C for
cour
on the right. Meanwhile an actor can remember the difference because of the similarity in sound between
cour
and
coeur
, or heart, which beats just to the left of centre. So the actor can move to the left backstage and emerge, as far as the audience is concerned, from the right without anyone getting into a muddle.

Our uncertainty in these matters is far more likely to play tricks on us when we have to choose between left and right than when we’re faced with opposites such as front–back or above–below. Ask a hundred people to take a writing pad out of the left side of a cupboard and there will always be a few who peer along the shelves to the right, but no one will kneel down if he’s asked to fetch something from the top of that same cupboard. When children learn to write, they can easily mix up the d and the b, whether they’re right- or left-handed, but only in exceptional cases do they mistake a p for a b. The difference between top and bottom, just like the difference between front and back, is far more obvious than the difference between left and right.

It’s exactly the same with animals, except that most have infinitely more difficulty with the left–right distinction than we do. They can easily see that a threat comes from the left or the right, or that there’s something good to be had on the left or the right, and respond accordingly, but what they rarely if ever manage to do is to link a choice between left and right to a stimulus that in itself has nothing to do with that distinction.

Suppose for example that we put a rat, a pigeon or some other creature into a cage with a button in it marked with an arrow that looks like this: ‘>’. If the arrow points to the left, then pressing the button produces a tasty morsel of food, but if the arrow points to the right then something unpleasant happens, such as an electric shock. The bird or animal’s task, therefore, is to learn to see which way the arrow is pointing and thereby deduce whether or not it’s advisable to press the button. Hardly any animals have proven capable of mastering this skill, but the results are quite different if the arrow points either upwards or downwards. Rats, pigeons, apes, even octopuses can learn to respond reasonably effectively in that situation. Up or down seems to be a clear and recognizable distinction, whereas in the eyes of an animal ‘<’ is indistinguishable from ‘>’. For a while it was thought that pigeons were an exception, until it turned out that those particularly cunning birds were tilting their heads as they looked, transforming the left–right distinction into an up–down one.

Our blind spot for the left–right distinction has to do with the fact that the difference between left and right has virtually no role to play in the natural world, or at least those parts of it that are visible to the naked eye. Above and below differ as strikingly in everyday reality as they do in essence. Birds of prey menace you exclusively from above, never from below. You dig holes in the ground, never in the sky. The distinction between front and back is no less fundamental: if you have to flee, or indeed if you want to catch something, then you need a clear idea of which is your front, otherwise you won’t get very far. This does not apply to left and right; in fact it may actually be a disadvantage to see the two sides as fundamentally different. After all, the same enemies might lurk on either side and the same desirable things might be found to our left or to our right. Anyone who, having already been attacked from the left, recognizes a danger to the right as ‘the same’ – and therefore quickly decides to escape by moving in the opposite direction – has a clear advantage over someone who sees a threat from the right as an entirely new phenomenon that must be judged on its own merits.

The left–right distinction is insignificant when it comes to the structure of plant and animal species, whereas the front–back distinction is usually quite clear, and the difference between top and bottom almost always. In the left–right plane, almost all organisms are symmetrical, with the exception of some species of shellfish. Their shells have an asymmetrical form, in most cases spiralling one way around but sometimes the reverse, although that makes no difference to the species. It’s a meaningless variation. We see a similar thing in flatfish: sometimes one side, sometimes the other grows into the lower half.

It’s a very different story in the world of the invisibly small, at the level of atoms and molecules. Molecules that are each other’s mirror image have completely different characteristics for that reason alone. Outside the microscopic world, which by definition we cannot observe without special devices, the left–right distinction is an important feature only of things made by man. An ability to distinguish between an image and its mirror image is required exclusively for items of cultural significance. This becomes clear if you compare the mirror image of a landscape photograph taken at random with the mirror image of a photograph of a typical man-made environment, such as a shopping street. With the first photo it’s far from easy to make out whether you are dealing with the original or the mirror image, but with the second it’s immediately obvious.

The alphabet is one of the cultural artefacts in which mirroring is a prominent factor. S, Z, R and N are simply incorrect if reversed (unless explicitly assigned significance in some way), but several letters of the alphabet are transformed into others if we look at them in the mirror. For example, p and q are left-right mirror images of each other, as are b and d, while p and q have the same shapes as b and d upside-down. If we reverse an n both horizontally and vertically we get a u. The uses of mirror-sensitivity are not limited to asymmetrical shapes like letters. The traffic rules, in which the distinction between left and right is a mainstay, is a wonderful example of perfect symmetrical mirroring. Whether you’re driving from Aberdeen to Yeovil or from Yeovil to Aberdeen, your image of the traffic is exactly the same.

Despite the subtle games we can play with mirror images, our memory is still set up in a way that coincides with the natural state of affairs – the animal within us. When we store away the images we see, we give low priority to the retention of information about their left–right orientation. This is clear from experiments that resemble a well-known parlour game. People are given a large number of random pictures to look at. A little later they are again presented with a series of pictures, some the same, some different, some in mirror image and some upside down. Time and again people prove able to recognize pictures they have seen before but in mirror image. They don’t even notice that the picture has been reversed. They are far less likely to recognize images that have been turned on their heads, especially in the case of abstract shapes; at least, they fail to give the appropriate response when asked. Mirror images of depictions that are stored in our memories do not stand out as different, whereas those reversed vertically do. No wonder children learning to write have such difficulty remembering the difference between d and b, while the distinction between p and b rarely causes them any trouble.

The way our bodies are constructed fits neatly within this general rule. The difference between our fronts and backs, or between our top and bottom halves, is significant and profound, just as in all other vertebrates, but the difference between left and right can barely be seen at all externally. On both sides we have an eye, a hand, a foot and a great deal else, and body parts of which we have only one, such as noses, navels, penises and vaginas, with all that goes with them, are right in the middle and themselves more or less symmetrical. The only exception is the parting in our hair. Plus natural blemishes such as birthmarks and warts, but then that’s what makes them blemishes.

Nevertheless, it’s because of the incompleteness of this apparent symmetry that we can tell left and right apart at all. If we were perfectly symmetrical, we would have no way of distinguishing between that which lies to our left and that which lies to our right. Our own mirror image, for example, would be exactly the same as our real-world image, so we would be unable to tell the difference between our actual appearance and the way we look in the mirror. As a result we would simply not notice that our image had been reversed. Nor would we notice if the entire world around us suddenly switched, as happened to Lewis Carroll’s Alice when she stepped through the looking-glass. Any experience we perceived on our left side would in no way differ from the same experience to our right. So we’d be able to see that a d and a b were each other’s mirror image if they were written next to each other on a piece of paper, but we’d never be able to explain how a d should be written. Freud’s childhood memory of having to work out which was his writing hand illustrates the point perfectly. When he no longer knew which was which, he made himself extra-asymmetrical by putting his writing hand to work.

The fact that children have so much more difficulty telling right from left could have to do with the fact that adults are less symmetrical than children. Like the rest of our bodies, our brains grow during childhood, not only in size but internally. Their structure changes.

The brain of a newborn baby is to some extent comparable to a recently built office block. The basic facilities are in place but as yet it’s unfurnished. On completion of the structure, all the rooms are interchangeable concrete spaces, but within a few months every part of the building has been occupied by one department or another. The third floor, for example, may have become the financial heart of the company, while the canteen is on the first floor; the left side of the fifth floor houses public relations and to the right of the lift are the sales staff. In the process, cupboards have been moved several times, desks turned around, extra lamps brought in. Things that didn’t appear in the initial plan for the layout have turned out to work better in practice. The way a building ends up is therefore determined partly by the initial blueprint and partly by a learning process, by trial and error.

In the same way, parts of our brains are furnished according to a standard plan that’s anchored in the genes of every new world citizen, while others develop according to a learning process generated by the external influences operating upon the child. Over the years a vast number of new connections are made between neurons and a good many existing connections disappear, so that ultimately a set of circuits emerges that can get us through adult life successfully.

In this sense the development of the human brain does not differ greatly from that of other mammals. Their brains too are incomplete at birth; they too need to experience the world before they fully reach adult-hood. In humans the process is longer and more complex, but there’s something else as well, something quite special. Human brains differ from those of other mammals in the size of the upper, outer layer, the cerebral cortex. It’s there that the so-called higher functions are located, including things we regard as typically human. In other mammals the cerebral cortex is symmetrical, consisting of two roughly identical halves connected by a broad bundle of axons called the
corpus callosum
. Only in humans, or at the very least in humans far more than in any other animal, some parts of the cortex that specialize in specific tasks are found on one side only. As a result the two halves of the brain, though largely identical at birth, eventually come to feature significant differences. They may look symmetrical, but adult human brains work asymmetrically to some extent. Many functions that have to do with speech are generally found in the left half, as are arithmetical skills, while the right half tends to be engaged with the final processing of visual and spatial sensations. The right side of the brain commands the databank of faces that ensures we don’t simply walk past family, friends and colleagues on the street without noticing them. People also somehow become able to control one hand better than the other. Because of this typically human process of one-sided specialization, known as lateralization, the brains of adults are far less symmetrical than those of small children.