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The Joy of Next

If you were asked to name the human brain’s greatest achievement, you might think first of the impressive artefacts it has produced–the Great Pyramid of Giza, the International Space Station or perhaps the Golden Gate Bridge. These are great achievements indeed, and our brains deserve their very own ticker-tape parade for producing them. But they are not the greatest. A sophisticated machine could design and build any one of these things because designing and building require knowledge, logic and patience, of which sophisticated machines have plenty. In fact, there’s really only one achievement so remarkable that even the most sophisticated machine cannot pretend to have accomplished it, and that achievement is conscious experience. Seeing the Great Pyramid or remembering the Golden Gate or imagining the Space Station are far more remarkable acts than is building any one of them. What’s more, one of these remarkable acts is even more remarkable than the others. To see is to experience the world as it is, to remember is to experience the world as it was, but to imagine–ah, to imagine is to experience the world as it isn’t and has never been, but as it might be. The greatest achievement of the human brain is its ability to imagine objects and episodes that do not exist in the realm of the real, and it is this ability that allows us to think about the future. As one philosopher noted, the human brain is an ‘anticipation machine’, and ‘making future’ is the most important thing it does.²

But what exactly does ‘making future’ mean? There are at least two ways in which brains might be said to make future, one of which we share with many other animals, the other of which we share with none. All brains–human brains, chimpanzee brains, even ordinary food-burying squirrel brains–make predictions about the immediate, local, personal future. They do this by using information about current events (‘I smell something’) and past events (‘Last time I smelled this smell, a big thing tried to eat me’) to anticipate the event that is most likely to happen to them next (‘A big thing is about to——’).³ But notice two features of this so-called prediction. First, despite the comic quips inside the parentheses, predictions such as these do not require the brain making them to have anything even remotely resembling a conscious thought. Just as an abacus can put two and two together to produce four without having thoughts about arithmetic, so brains can add past to present to make future without ever thinking about any of them. In fact, it doesn’t even require a brain to make predictions such as these. With just a little bit of training, the giant sea slug known as Aplysia parvula can learn to predict and avoid an electric shock to its gill, and as anyone with a scalpel can easily demonstrate, sea slugs are inarguably brainless. Computers are also brainless, but they use precisely the same trick the sea slug does when they turn down your credit card because you were trying to buy dinner in Paris after buying lunch in LA. In short, machines and invertebrates prove that it doesn’t take a smart, self-aware, conscious brain to make simple predictions about the future.

The second thing to notice is that predictions such as these are not particularly far-reaching. They are not predictions in the same sense that we might predict the annual rate of inflation, the intellectual impact of postmodernism, the heat death of the universe, or Madonna’s next hair colour. Rather, these are predictions about what will happen in precisely this spot, precisely next, to precisely me, and we call them predictions only because there is no better word for them in the English language. But the use of that term—with its inescapable connotations of calculated, thoughtful reflection about events that may occur anywhere, to anyone, at any time–risks obscuring the fact that brains are continuously making predictions about the immediate, local, personal future of their owners without their owners’ awareness. Rather than saying that such brains are predicting let’s say that they are nexting.

Yours is nexting right now. For example, at this moment you may be consciously thinking about the sentence you just read, or about the key ring in your pocket that is jammed uncomfortably against your thigh, or about whether the War of 1812 really deserves its own overture. Whatever you are thinking, your thoughts are surely about something other than the word with which this sentence will end. But even as you hear these very words echoing in your very head, and think whatever thoughts they inspire, your brain is using the word it is reading right now and the words it read just before to make a reasonable guess about the identity of the word it will read next which is what allows you to read so fluently.⁴ Any brain that has been raised on a steady diet of film noir and cheap detective novels fully expects the word night to follow the phrase It was a dark and stormy and thus when it does encounter the word night it is especially well prepared to digest it. As long as your brain’s guess about the next word turns out to be right, you cruise along happily, left to right, left to right, turning black squiggles into ideas, scenes, characters and concepts, blissfully unaware that your nexting brain is predicting the future of the sentence at a fantastic rate. It is only when your brain predicts badly that you suddenly feel avocado.

That is, surprised. See?

Now, consider the meaning of that brief moment of surprise. Surprise is an emotion we feel when we encounter the unexpected–for example, thirty-four acquaintances in paper hats standing in our living room yelling ‘Happy birthday!’ as we walk through the front door with a bag of groceries and a full bladder–and thus the occurrence of surprise reveals the nature of our expectations. The surprise you felt at the end of the last paragraph reveals that as you were reading the phrase it is only when your brain predicts badly that you suddenly feel…, your brain was simultaneously making a reasonable prediction about what would happen next. It predicted that sometime in the next few milliseconds your eyes would come across a set of black squiggles that encoded an English word that described a feeling, such as sad or nauseous or even surprised. Instead, it encountered a fruit, which woke you from your dogmatic slumbers and revealed the nature of your expectations to anyone who was watching. Surprise tells us that we were expecting something other than what we got, even when we didn’t know we were expecting anything at all.

Because feelings of surprise are generally accompanied by reactions that can be observed and measured–such as eyebrow arching, eye widening, jaw dropping, and noises followed by a series of exclamation marks–psychologists can use surprise to tell them when a brain is nexting. For example, when monkeys see a researcher drop a ball down one of several chutes, they quickly look to the bottom of that chute and wait for the ball to reemerge. When some experimental trickery causes the ball to emerge from a different chute than the one in which it was deposited, the monkeys display surprise, presumably because their brains were nexting.⁵ Human babies have similar responses to weird physics. For example, when babies are shown a video of a big red block smashing into a little yellow block, they react with indifference when the little yellow block instantly goes careening off the screen. But when the little yellow block hesitates for just a moment or two before careening away, babies stare like bystanders at a train wreck–as though the delayed careening had violated some prediction made by their nexting brains.⁶ Studies such as these tell us that monkey brains ‘know’ about gravity (objects fall down, not sideways) and that baby human brains ‘know’ about kinetics (moving objects transfer energy to stationary objects at precisely the moment they contact them and not a few seconds later). But more important, they tell us that monkey brains and baby human brains add what they already know (the past) to what they currently see (the present) to predict what will happen next (the future). When the actual next thing is different from the predicted next thing, monkeys and babies experience surprise.

Our brains were made for nexting, and that’s just what they’ll do. When we take a stroll on the beach, our brains predict how stable the sand will be when our foot hits it, and then adjust the tension in our knee accordingly. When we leap to catch a Frisbee, our brains predict where the disc will be when we cross its flight path, and then bring our hands to precisely that point. When we see a sand crab scurry behind a bit of driftwood on its way to the water, our brains predict when and where the critter will reappear, and then direct our eyes to the precise point of its reemergence. These predictions are remarkable in both the speed and accuracy with which they are made, and it is difficult to imagine what our lives would be like if our brains quit making them, leaving us completely ‘in the moment’ and unable to take our next step. But while these automatic, continuous, nonconscious predictions of the immediate, local, personal future are both amazing and ubiquitous, they are not the sorts of predictions that got our species out of the trees and into dress slacks. In fact, these are the kinds of predictions that frogs make without ever leaving their lily pads, and hence not the sort that The Sentence was meant to describe. No, the variety of future that we human beings manufacture–and that only we manufacture–is of another sort entirely.

The Ape That Looked Forward

Adults love to ask children idiotic questions so that we can chuckle when they give us idiotic answers. One particularly idiotic question we like to ask children is this: ‘What do you want to be when you grow up?’ Small children look appropriately puzzled, worried perhaps that our question implies they are at some risk of growing down. If they answer at all, they generally come up with things like ‘the candy guy’ or ‘a tree climber’. We chuckle because the odds that the child will ever become the candy guy or a tree climber are vanishingly small, and they are vanishingly small because these are not the sorts of things that most children will want to be once they are old enough to ask idiotic questions themselves. But notice that while these are the wrong answers to our question, they are the right answers to another question, namely, ‘What do you want to be now?’ Small children cannot say what they want to be later because they don’t really understand what later means.⁷ So, like shrewd politicians, they ignore the question they are asked and answer the question they can. Adults do much better, of course. When a thirtyish Manhattanite is asked where she thinks she might retire, she mentions Miami, Phoenix or some other hotbed of social rest. She may love her gritty urban existence right now, but she can imagine that in a few decades she will value bingo and prompt medical attention more than art museums and squeegee men. Unlike the child who can only think about how things are, the adult is able to think about how things will be. At some point between our high chairs and our rocking chairs, we learn about later.⁸

Later! What an astonishing idea. What a powerful concept. What a fabulous discovery. How did human beings ever learn to preview in their imaginations chains of events that had not yet come to pass? What prehistoric genius first realized that he could escape today by closing his eyes and silently transporting himself into tomorrow? Unfortunately, even big ideas leave no fossils for carbon dating, and thus the natural history of later is lost to us forever. But paleontologists and neuroanatomists assure us that this pivotal moment in the drama of human evolution happened sometime within the last 3 million years, and that it happened quite suddenly. The first brains appeared on earth about 500 million years ago, spent a leisurely 430 million years or so evolving into the brains of the earliest primates, and another 70 million years or so evolving into the brains of the first protohumans. Then something happened–no one knows quite what, but speculation runs from the weather turning chilly to the invention of cooking–and the soon-to-be-human brain experienced an unprecedented growth spurt that more than doubled its mass in a little over two million years, transforming it from the one-and-a-quarter-pound brain of Homo habilis to the nearly three-pound brain of Homo sapiens.⁹

Now, if you were put on a hot-fudge diet and managed to double your mass in a very short time, we would not expect all of your various body parts to share equally in the gain. Your belly and buttocks would probably be the major recipients of newly acquired flab, while your tongue and toes would remain relatively svelte and unaffected. Similarly, the dramatic increase in the size of the human brain did not democratically double the mass of every part so that modern people ended up with new brains that were structurally identical to the old ones, only bigger. Rather, a disproportionate share of the growth centred on a particular part of the brain known as the frontal lobe, which, as its name implies, sits at the front of the head, squarely above the eyes (see figure 2). The low, sloping brows of our earliest ancestors were pushed forward to become the sharp, vertical brows that keep our hats on, and the change in the structure of our heads occurred primarily to accommodate this sudden change in the size of our brains. What did this new bit of cerebral apparatus do to justify an architectural overhaul of the human skull? What is it about this particular part that made nature so anxious for each of us to have a big one? Just what good is a frontal lobe?

Fig. 2. The frontal lobe is the recent addition to the human brain that allows us to imagine the future.

Until fairly recently, scientists thought it was not much good at all, because people whose frontal lobes were damaged seemed to do pretty well without them. Phineas Gage was a foreman for the Rutland Railroad who, on a lovely autumn day in 1848, ignited a small explosion in the vicinity of his feet, launching a three-and-a-half-foot-long iron rod into the air, which Phineas cleverly caught with his face. The rod entered just beneath his left cheek and exited through the top of his skull, boring a tunnel through his cranium and taking a good chunk of frontal lobe with it (see figure 3). Phineas was knocked to the ground, where he lay for a few minutes. Then, to everyone’s astonishment, he stood up and asked if a coworker might escort him to the doctor, insisting all the while that he didn’t need a ride and could walk by himself, thank you. The doctor cleaned some dirt from his wound, a coworker cleaned some brain from the rod, and in a relatively short while, Phineas and his rod were back about their business.¹⁰ His personality took a decided turn for the worse–and that fact is the source of his fame to this day–but the more striking thing about Phineas was just how normal he otherwise was. Had the rod made hamburger of another brain part–the visual cortex, Brace’s area, the brain stem–then Phineas might have died, gone blind, lost the ability to speak or spent the rest of his life doing a convincing impression of a cabbage. Instead, for the next twelve years, he lived, saw, spoke, worked and travelled so uncabbagely that neurologists could only conclude that the frontal lobe did little for a fellow that he couldn’t get along nicely without.¹¹ As one neurologist wrote in 1884, ‘Ever since the occurrence of the famous American crowbar case it has been known that destruction of these lobes does not necessarily give rise to any symptoms.’¹²

Fig. 3. An early medical sketch showing where the tamping iron entered and exited Phineas Gage’s skull.

But the neurologist was wrong. In the nineteenth century, knowledge of brain function was based largely on the observation of people who, like Phineas Gage, were the unfortunate subjects of one of nature’s occasional and inexact neurological experiments. In the twentieth century, surgeons picked up where nature left off and began to do more precise experiments whose results painted a very different picture of frontal lobe function. In the 1930s, a Portuguese physician named Antonio Egas Moniz was looking for a way to quiet his highly agitated psychotic patients when he heard about a new surgical procedure called frontal lobotomy, which involved the chemical or mechanical destruction of parts of the frontal lobe. This procedure had been performed on monkeys, who were normally quite angry when their food was withheld, but who reacted to such indignities with unruffled patience after experiencing the operation. Egas Moniz tried the procedure on his human patients and found that it had a similar calming effect. (It also had the calming effect of winning Egas Moniz the Nobel Prize for Medicine in 1949.) Over the next few decades, surgical techniques were improved (the procedure could be performed under local anesthesia with an ice pick) and unwanted side effects (such as lowered intelligence and bed-wetting) were diminished. The destruction of some part of the frontal lobe became a standard treatment for cases of anxiety and depression that resisted other forms of therapy.¹³ Contrary to the conventional medical wisdom of the previous century, the frontal lobe did make a difference. The difference was that some people seemed better off without it.

But while some surgeons were touting the benefits of frontal lobe damage, others were noticing the costs. Although patients with frontal lobe damage often performed well on standard intelligence tests, memory tests and the like, they showed severe impairments on any test–even the very simplest test–that involved planning. For instance, when given a maze or a puzzle whose solution required that they consider an entire series of moves before making their first move, these otherwise intelligent people were stumped.¹⁴ Their planning deficits were not limited to the laboratory. These patients might function reasonably well in ordinary situations, drinking tea without spilling and making small talk about the curtains, but they found it practically impossible to say what they would do later that afternoon. In summarizing scientific knowledge on this topic, a prominent scientist concluded: ‘No prefrontal symptom has been reported more consistently than the inability to plan…. The symptom appears unique to dysfunction of the prefrontal cortex…[and] is not associated with clinical damage to any other neural structure.’¹⁵

Now, this pair of observations–that damage to certain parts of the frontal lobe can make people feel calm but that it can also leave them unable to plan–seem to converge on a single conclusion. What is the conceptual tie that binds anxiety and planning? Both, of course, are intimately connected to thinking about the future. We feel anxiety when we anticipate that something bad will happen, and we plan by imagining how our actions will unfold over time. Planning requires that we peer into our futures, and anxiety is one of the reactions we may have when we do.¹⁶ The fact that damage to the frontal lobe impairs planning and anxiety so uniquely and precisely suggests that the frontal lobe is the critical piece of cerebral machinery that allows normal, modern human adults to project themselves into the future. Without it we are trapped in the moment, unable to imagine tomorrow and hence unworried about what it may bring. As scientists now recognize, the frontal lobe ‘empowers healthy human adults with the capacity to consider the self’s extended existence throughout time’.¹⁷? As such, people whose frontal lobe is damaged are described by those who study them as being ‘bound to present stimuli’,¹⁸ or ‘locked into immediate space and time’,¹⁹ or as displaying a ‘tendency toward temporal concreteness’.²⁰ In other words, like candy guys and tree climbers, they live in a world without later.

The sad case of the patient known as N.N. provides a window into this world. N.N. suffered a closed head injury in an automobile accident in 1981, when he was thirty years old. Tests revealed that he had sustained extensive damage to his frontal lobe. A psychologist interviewed N.N. a few years after the accident and recorded this conversation:

PSYCHOLOGIST: What will you be doing tomorrow?

N.N.: I don’t know.

PSYCHOLOGIST: DO you remember the question?

N.N.: About what I’ll be doing tomorrow?

PSYCHOLOGIST: Yes, would you describe your state of mind when you try to think about it?

N.N.: Blank, I guess…It’s like being asleep…like being in a room with nothing there and having a guy tell you to go find a chair, and there’s nothing there…like swimming in the middle of a lake. There’s nothing to hold you up or do anything with.²¹

N.N.’s inability to think about his own future is characteristic of patients with frontal lobe damage. For N.N., tomorrow will always be an empty room, and when he attempts to envision later, he will always feel as the rest of us do when we try to imagine nonexistence or infinity. Yet, if you struck up a conversation with N.N. on the subway, or chatted with him while standing in a queue at the post office, you might not know that he was missing something so fundamentally human. After all, he understands time and the future as abstractions. He knows what hours and minutes are, how many of the latter there are in the former, and what before and after mean. As the psychologist who interviewed N.N. reported: “He knows many things about the world, he is aware of this knowledge, and he can express it flexibly. In this sense he is not greatly different from a normal adult. But he seems to have no capacity of experiencing extended subjective time…. He seems to be living in a ‘permanent present…’”²²

A permanent present–what a haunting phrase. How bizarre and surreal it must be to serve a life sentence in the prison of the moment, trapped forever in the perpetual now, a world without end, a time without later. Such an existence is so difficult for most of us to imagine, so alien to our normal experience, that we are tempted to dismiss it as a fluke–an unfortunate, rare and freakish aberration brought on by traumatic head injury. But in fact, this strange existence is the rule and we are the exception. For the first few hundred million years after their initial appearance on our planet, all brains were stuck in the permanent present, and most brains still are today. But not yours and not mine, because two or three million years ago our ancestors began a great escape from the here and now, and their getaway vehicle was a highly specialized mass of grey tissue, fragile, wrinkled and appended. This frontal lobe–the last part of the human brain to evolve, the slowest to mature and the first to deteriorate in old age–is a time machine that allows each of us to vacate the present and experience the future before it happens. No other animal has a frontal lobe quite like ours, which is why we are the only animal that thinks about the future as we do. But if the story of the frontal lobe tells us bow people conjure their imaginary tomorrows, it doesn’t tell us why.