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We live in a world of bewildering complexity, and there is generally far too much going on around us for us to be aware of everything the sights, sounds, smells, tastes and touches that constantly harass our senses. Our brains have therefore evolved to select some aspects of the world for mental processing, and ignore the rest. That selection process is what we call attention. Its selective nature is easily demonstrated. In one famous example, people are shown a moving clip of a basketball game, and are generally so intent on watching the players that they fail to notice a gorilla that has wandered onto the court. If you play messages via earphones simultaneously into each ear and ask people to listen to one of them, they generally fail to pick up any information from the other, even though it’s equally loud. This proves that attention can be operated internally, by the mind, and not simply by orienting the ears. Visual attention, however, generally depends on where the eyes are looking. Even so, it is possible to look straight ahead and yet pay attention to events out of the corner of the eye a device that can be used by rugby or netball players to trick the opposition. Or by school teachers, anxious to detect mischief makers. Nature has equipped us with automatic mechanisms to capture events that might be important to survival. Loud noises, sudden movements, brilliant flashes of light these all divert us from what we are doing, in case they signal danger. So does extreme pain. Alarm systems are typically loud and jarring, although we may also be tuned to more subtle events. A mother may be especially alert to the sound of her baby crying even from a distance, and all of us are sensitised to the sound of our own names being spoken, even if whispered. In Shakespeare’s Richard II, John of Gaunt observes “...they say the tongues of dying men enforce attention, like deep harmony”. However, we are not slaves to the environment; attention can be controlled voluntarily, as when we choose to read a book, listen to a lecture or a piece of music, or solve a crossword puzzle. To a degree, then, we can filter out most environmental distractions, although not all. In his poem The Canonization, the poet John Donne famously exclaimed, “For God’s sake hold thy tongue, and let me love.” Attention is not always directed to the external world. We can beam it inwards, as when we are lost in thought or reverie. Attention requires a fine balance between concentration on the task at hand and awareness of the environment. We cannot be so intent on solving a Sudoku puzzle that we fail to observe the conflagration around us, nor can we be so easily distracted that we fail to complete any task requiring sustained concentration. Sometimes the balance is disturbed, as in some cases of brain injury, or in what is called attention deficit disorder. In general, boys seem more prone to this than girls. In a hunter-gatherer society, it was probably the males who did the hunting, and this required constant attention to danger and opportunity. The human brain is curiously asymmetrical in the way it controls attention. The left brain attends to the right side of space, the right to both sides, albeit with some bias towards the left. Damage to the right side may therefore cause the patient to lose awareness of events on the left, a phenomenon known as hemineglect. The patient may eat from only the right side of the plate, dress only the right side of the body, ignore those who address them from the left, and are easily beaten at chess by an attack from the left flank. A famous example is the German artist Lovis Corinth (1858–1925), who suffered a right-brain stroke in 1911 but continued to draw and paint for the next 14 years—much of his work shows a neglect of the left side. Just why the brain should function in this asymmetrical way is not clear. Perhaps it’s because in most of us the left side of the brain is largely taken up with language, and so loses some of its capacity to direct attention to space. Left-brain damage seldom results in neglect of the right side, or does so only transiently, and there is no evidence that nonhuman animals show a similar asymmetry. We are the lopsided ape.
Much of our social life has to do with figuring out what is going on in the minds of others. Does he love me? Have I offended her? And the lecturer’s nightmare: Do they understand what on Earth I’m talking about? This awareness of what others might be thinking is known as theory of mind. It underlies our natural tendency to empathise with others, to share their happiness or distress, but it also allows us to interact with others in more complex ways, some of them devious. Emotion is the easiest state to read, as it is usually written on the face or in bodily signs. Even mice react more strongly to pain if they perceive pain in others, and monkeys refuse to pull a chain to get food if doing so delivers a shock to a companion. Chimpanzees, but not monkeys, offer consolation to others in distress. A juvenile chimp, for instance, puts a comforting arm around a screaming adult who has been defeated in a fight. Chimpanzees also seem to know when another chimp is looking at them, and steal food when a dominant chimp is not looking. It is a step up, though, to know what another individual knows or believes, a talent perhaps restricted to humans. One way to assess it in children is the Sally-Anne test. The child is shown a scene involving two dolls, one called Sally and one called Anne. Sally has a basket and Anne has a box. Sally then puts a marble in her basket and leaves the scene. While Sally is away Anne takes the marble out of the basket and puts it in her box. Sally then comes back, and the child is asked where she will look for her marble. Children under the age of four typically say Sally will look in the box, where the marble actually is. Older children will understand that Sally did not see the marble being shifted, and will correctly say that she will look in the basket. They understand that Sally has a false belief. In contrast, people with autism seem to lack the ability to read minds. One celebrated case is Temple Grandin, who has a PhD in animal science and works as a teacher and researcher in the US. Otherwise clearly intelligent, she has written several books, three of which describe her own condition and the manner in which she has dealt with it. She has had to teach herself painstakingly how people act in different circumstances, so that she knows how to behave appropriately in social settings. One bonus arising from this strategy is that her habit of detailed observations of behaviour has provided insights into the behaviour of animals. A BBC Horizon documentary about her in 2006 had the rather unkind title, “The Woman Who Thinks Like a Cow”. Such cases aside, theory of mind can operate to establish intricate networks that guide much of our social activity. In Shakespeare’s Twelfth Night, Maria foresees that Sir Toby will eagerly anticipate that Olivia will judge Malvolio absurdly impertinent to suppose that she wishes him to regard himself as her preferred suitor. Each italicised word attributes a state of mind. Theory of mind is recursive we may fancy we know not only what others are thinking, but also what they think we are thinking. In his book Jokes and Their Relation to the Unconscious, Sigmund Freud tells a story of a man who meets a business rival at a train station and asks where he is going. The business rival replies he is going to Minsk. The first man then says, “You’re telling me you’re going to Minsk because you want me to think you’re going to Pinsk. But I happen to know that you are going to Minsk, so why are you lying to me?” It has been suggested that theory of mind arose in the Pleistocene, when our hunter-gatherer forebears had to bond socially in order to survive on the open savanna, foraging for food and competing with lions, hyenas and other dangerous animals. But once they had conquered nature, tribes of hominins began to compete with each other, leading to the subtle combination of co-operation and deception that drives our social lives today. The dangerous animals we must now deal with are not so much snakes as sellers of snake oil. And they are everywhere—in commerce, politics, religion and even, dare I say, the university.
Got a bad memory? It’s actually much worse than you think, for the simple reason that you don’t know how much you have forgotten. I was at a school reunion not so long ago, and was shocked at my failure to remember many of the stories my old classmates told, even though I seemed to feature in most of them. For a while I feared that dementia was setting in, until I discovered that others failed to recognise some of the stories I told. I was also consoled by one memory that did return—the memory that some of my old mates were inveterate liars.
Most linguists and cognitive scientists agree that we humans are uniquely blessed with the gift of language. Compared to human speech, animal calls are stereotyped and fixed, and tied to specific situations such as mating, territorial claims, expressing aggression, or raising alarm. The nearest equivalent to speech seems to come, not from our nearest relatives the great apes, but from birds. Parrots, for example, can imitate human speech, and even be taught to answer simple questions, like naming the colour of a block, or counting the number of objects in a display (but only up to about six). Songbirds in the wild generate complex songs, but these are largely repetitive and probably serve primarily as identification codes. They have none of the individual variety that enables humans to express a virtually infinite range of ideas, thoughts and opinions.
Our ability to recall past events in our lives is part of what has come to be called mental time travel. Our memories, however imperfect, probably evolved not to provide a faithful record of the past, but rather to supply information for building future scenarios. This allows us to plan events in detail, or to weigh up different possibilities before the future is upon us. It also enables us to create what have been called “future selves”, models of what we hope to become once we have completed an education, found a mate, bought a house, chosen a career or cleaned out the basement. Like Browning’s grammarian, a number of cognitive scientists, myself among them, have controversially claimed that only humans can travel mentally in time. Animal researchers have risen to the challenge, but it has proven peculiarly difficult to show that non-human animals can indeed mentally relive the past or imagine the future. In humans, of course, we can simply ask, but in animals lacking language we need other techniques. The problem isn’t simple. Consider for example a dog that buries a bone, and later returns to dig it up. This need not mean that it actually remembers burying the bone. It may simply have knowledge of where the bone is buried, without mentally reliving the act itself. One suggestion is that we could be surer of true remembering if we could show that an animal that buries food can recollect not only what is buried and where it is buried, but also when it was buried. Scrub jays, pesky little birds that cache food for later consumption, may well pass this what-where-when test (also called the www test). If they cache both worms and nuts in different places, they will recover the worms if a relatively short time has elapsed, since they prefer fresh worms to nuts. But if a longer time has elapsed, they will go for the nuts, evidently because they know the worms will no longer be fresh. This suggests that they remember not only what they cached and where they cached it, but also when they cached it. Moreover, if jays are watched by another while caching food, they later re-cache it, presumably to thwart the watching bird from stealing the food. But they will only re-cache if they themselves have stolen food; even in scrub jays, it takes a thief to know a thief. Re-caching might be taken as evidence that the birds can imagine a future event of theft. These are among the increasingly clever experiments designed to show that nonhuman species can travel mentally in time. But I’m not yet convinced. My knowledge of such events as my own birth passes the www test—I know where I was born, when I was born and, heaven help me, what was born, but of course I have no actual memory of the event. The critical distinction is between what we know and what we actually remember, and it remains a real challenge to demonstrate that distinction in birds, or in any non-human species. I invite suggestions. Be that as it may, there can be no doubt that we humans are obsessed with time. Of course other animals plan for the future by migrating or by hoarding food, but these activities are instinctive, driven by changes of season, and have limited provenance. In our own activities we are driven by time itself, with appointments, deadlines, wedding anniversaries and taxes. Although generally adaptive, reliving the past can be an emotional hazard, as when we recall previous embarrassment, and anticipation of the future can be a source of anxiety, as in a visit to the dentist or an appointment with the boss—or the inevitability of death, leading perhaps to religions that promise an after-life. Sometimes, though, the knowledge that time will pass is a comfort, as when Viola in Shakespeare’s Twelfth Night, masquerading as a man, finds herself in an impossible situation and exclaims: O Time, thou must untangle this, not I; It is too hard a knot for me t’untie! Language itself may have evolved precisely to allow us to share our experiences, and its lack in other species may reflect the absence of mental time travel. Sharing allows us to benefit from the memories and plans of others. And to be adaptive, the tales we tell need not be true. This explains not only our predilection for gossip and shared confidences,but also the human obsession with fiction, whether through stories around the campfire, novels, plays or TV soaps. Or, you may think,columns like this.
Giacomo Rizzolatti is a neuroscientist. With his unruly hair and moustache, he looks like a reincarnation of Albert Einstein. He is excitable, enthusiastic and friendly, and he runs a busy laboratory in Parma, Italy. Giacomo records the activity of single neurons in the brains of monkeys. In the frontal cortex are neurons, which are active whenever the monkey reaches to grasp something, such as a peanut. The recording device can be hooked up to a speaker system, so that whenever a neuron fires you hear a crackling sound. One day, Giacomo was surprised to hear this sound, not just when the animal itself reached, but when a person in front of the animal reached for the nut. Neurons that respond both when the monkey makes a movement and when it observes the same movement made by another individual have come to be known as mirror neurons. They might also be described as “monkey see, monkey do” neurons. To neuroscientists, the discovery came as a revelation; indeed one prominent scientist remarked that mirror neurons will do for psychology what DNA has done for biology. You may well wonder why. The brain has traditionally been viewed as an input-output device, with some neurons responsive to input, others to output, and some in between that we might suppose to represent thought. Mirror neurons, though, seem to imply a direct mapping between input to output, as though we have a ready-made system for understanding the bodily actions of others in terms of our own actions. Perhaps you have found yourself squirming on the couch as you watch sport on TV, in synchrony with the flannelled fools or muddied oafs on the screen. You can blame your mirror neurons. Mirror neurons are quite versatile. In the monkey, they fire not only when the animal sees an action, but also when it hears the sound of a familiar action, such as paper being torn or nuts being cracked open. Brain-imaging experiments show that we humans also have mirror neurons, and they respond to a wide variety of bodily actions. They enable us to resonate with the thoughts and feelings of others, as reflected in their actions, providing a natural explanation for human empathy and what has been called “theory of mind.” The condition known as autism, characterised by an inability to understand the mental states of others, is now widely attributed to a failure of the mirror-neuron system. Mirror neurons may also help explain how we understand speech, which seems to border on the miraculous. Speech consists of packets of sound delivered at high rates, complicated by the fact that sounds that you hear as the same can actually be very different, depending on the contexts in which they are embedded. For example, b sounds in words like battle, bottle, beer, bug, rabbit, Beelzebub, or flibbertigibbet probably sound much the same to you, but the actual acoustic streams created by these b sounds vary widely, to the point that they actually have very little in common. This surprising fact, discovered only when sophisticated ways of analysing speech sounds were developed, has long been the bane of attempts to programme computers to recognise speech. Computers can now be painstakingly programmed to identify spoken words, but with only moderate success, and nothing like the facility of a normal four-year-old. One suggested solution to this problem was the so-called motor theory of speech perception, which holds that we perceive speech, not in terms of its acoustic properties, but in terms of how it is produced. The discovery of mirror neurons provided a strong boost for this theory. Thanks to your mirror neurons, you effectively map the speech of others directly onto your own mechanism for producing that speech. “Monkey see, monkey do” becomes “listener hear, listener do.” Mirror neurons almost certainly don’t come pre-programmed. They need to be tuned. Much of that tuning probably happens in childhood. My guess is that when infants babble, they are in effect tuning themselves to the sounds of speech, and mapping them onto their own production of sounds. That tuning is specific to the sounds of their native language, which is why foreign languages sound not only incomprehensible, but also nearly impossible to parse into their underlying sound patterns. And we are of course tuned into other actions as well, such as sporting skills and playing musical instruments. It’s fitting that mirror neurons were first discovered in the context of arm movements. With Italian verve, Giacomo Rizzolatti gestures as he talks, no doubt activating those same neurons.
Cack-handed, cow-pawed, dolly-pawed, ker-handed, left-plug, southpaw, squiffy, these are just some of the names that have been applied to left-handers. They have an air of insult, implying that lefties are somehow inferior, or at least odd. On the other hand, as it were, we right-handers are, well, just right. Our language betrays the distinction in other ways too; gauche and sinister originally meant “left”, while adroit and dexterous have an agreeable air of rightness, if not righteousness.
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