We rely very largely on our remembered pasts to construct our futures. Memory, in the form of knowledge as well as of remembered episodes, provides the building blocks from which to construct future plans. In the previous chapter, I referred to experiments in which people are asked to remember 100 episodes and identify a person, an object and a location. These experiments then continue as follows. We rearrange the remembered elements into new combinations, and our subjects are then asked to imagine future episodes built around them. For instance, a subject might remember her friend Mary dropping her laptop in the library, her brother Tom falling off his bicycle in the park, or her partner Shane cooking sausages in the kitchen. She might later be asked to imagine a future episode with her friend Mary cooking sausages in the park—an event that never happened, but is easily imagined. Our studies show that the areas in the brain activated by remembering these past events overlap extensively with the areas activated by the imagined future events. The brain hardly knows the difference.
People with amnesia typically have as much difficulty in imagining future events as they do in remembering past ones. Neither Henry Molaison nor Clive Wearing, whom we encountered in the previous chapter, could envisage future episodes any more than they could remember past ones. Deborah Wearing entitled her book on Clive Forever Today, and Suzanne Corkin called her book on Henry Molaison Permanent Present Tense; both titles capture the fact that both Clive and Henry had no sense of either past or future. Their minds were stuck in the present, with nowhere to wander. When Henry was once asked: ‘What do you think you’ll do tomorrow?’ he replied: ‘Whatever is beneficial.’ Perhaps his inability to mentally wander into past or future relieved him of the worry that often plagues our mind-wanderings, and made him an exceptionally agreeable and cooperative subject.
Here’s another patient with deep amnesia, known as ‘N.N.’, in conversation with the psychologist Endel Tulving:
E.T.: Let’s try the question again about the future. What will you be doing tomorrow? (There is a 15-second pause.)
N.N.: I don’t know.
E.T.: Do you remember the question?
N.N.: About what I’ll be doing tomorrow?
E.T.: Yes. How would you describe your state of mind when you try to think about it? (A 5-second pause.)
N.N.: Blank. I guess.
When asked to compare his state of mind when he is trying to think about what he will be doing tomorrow with his state of mind when he thinks about what he did yesterday, N.N. described it as ‘a big blankness’ that was ‘like swimming in the middle of a lake. There’s nothing there to hold you up or do anything with.’
Many of the scenarios we envisage in the future, such as a dinner party, are based on past episodes, with some rearrangement to accommodate a new location, or a new combination of people. Perhaps this helps explain why memory for episodes itself is not always accurate. If we are to design futures based on our memories, we need our memories to be useful rather than accurate. By constructing possible futures, we can then select what seems the best plan—the most fun, perhaps, or the least likely to prove disastrous. In our mind’s eye, we can imagine different scenarios for a wedding, say—where to hold it, who to invite, what music to play, even whether to go through with it. We play out different versions of a job interview, a new date, a tennis match, with the hope of figuring out the best strategy. The very flexibility of our memories can make for well-adjusted futures, but play havoc with the remembered past.
As children grow, their capacities to remember the past and imagine the future seem to surface together, somewhere between the ages of three and four. Neither capacity, though, comes about as a sudden dawning. Three-year-olds often seem unable to tell you what happened at nursery school or playcentre, or what might happen tomorrow, yet they learn things, such as new songs or games—even new words, some of which they shouldn’t use. They may have a sense of things that happened, or that will happen, but lack the mental machinery to put together a coherent scenario. Work by Thomas Suddendorf and colleagues suggests, though, that by age four most children have the basic mental components to be able to construct a possible future event. It may be that language in younger children is not well enough developed, so they can’t find the words to describe what they did or what they plan to do. This argument, though, can be reversed. Language itself is designed to convey the non-present, and perhaps doesn’t really develop until the sense of time itself emerges. In evolution, too, some capacity for mental time travel may well have evolved before we gained the ability to talk about our mental travels, as I shall explore in the next chapter.
In the previous chapter, I suggested that we adapt our memories to create images of ourselves—politicians, for instance, seem especially prone to recalling acts of heroism that did not actually occur. We also create future images. William James, brother of the novelist Henry and regarded by some as the founder of scientific psychology, wrote of ‘potential social Me’ as distinct from ‘immediate present Me’ and ‘Me of the past’. More recently, Hazel Markus and Paula Nurius write similarly of ‘possible selves’, based on how we see ourselves in the past but looking forward to new images of the self in the future. The idea of different possible selves provides much of the motivation that guides us as we plough through life. As Markus and Nurius put it: ‘I am now a psychologist, but I could be a restaurant owner, a marathon runner, a journalist, or the parent of a handicapped child.’ Future images can be both positive and negative—I can imagine myself as a roaring success, whether at parties, on the rugby field, or in scientific achievement, or I can see myself as a dismal failure at everything I do. Sigh.
Our imagined future selves can even extend beyond death. The ability to imagine beyond the reach of a lifetime reinforces religious belief, as we create for ourselves imagined heavens or hells. People can even be induced into bleak and self-destructive actions in their present lives through promise of a better life after death. Muslim children are taught from an early age that the main purpose of life in this world is to prepare oneself for an eternal and blissful life in the next, a promise that no doubt helped motivate the terrorists who flew planes into the Twin Towers in New York on 11 September 2001. The Japanese kamikaze pilots who died for their emperor in World War II may have similarly believed that they would be rewarded in the next life. Kamikaze means ‘divine wind’, and also refers to a cocktail made of triple parts vodka, triple sec and lime juice—a cocktail, perhaps, to die for. Various Christian sects have also indulged in flagellation, vows of poverty, or vows of silence, perhaps in the hope that they would lead more idyllic lives after death. The very notions of heaven and hell can be used to great effect to manipulate human behaviour, often for the benefit of kings and overlords. The offer of life after death, with associated rewards and punishments, is remarkably ingenious, since there seems no way in which we can be either gratified or disappointed—at least if these emotions are restricted to the living.
There may be less reason to believe in a life before one’s own incarnation, since it has little consequence for the present life—although it may lead one to claim special qualities based on an earlier existence. One of my former classmates fervently believes he is the reincarnation of Benjamin Franklin. Reincarnation is a central tenet of Indian religions, as well as of a number of others, such as druidism and theosophy. Several Greek philosophers, including Plato, Pythagoras and Socrates, believed in reincarnation. In Buddhist philosophy, different incarnations can spread across six different realms of existence, including the human, the animal, and several kinds of superhuman existence. Only rarely, they say, is a person reborn in the form of a human. A possible exception, if my old classmate is to be believed, was Benjamin Franklin. These beliefs are all testimony to the inventiveness of mental time travel.
Many, if not most, of our activities are directed in one way or another to the future, but need not actually involve mental time travel. Instinctive behaviours evolved precisely because they increase the chances of
survival, or the survival of our offspring—that’s what evolution is all about. Even instinct, then, is future-oriented. We may flee from danger, fight the aggressor, eat the apple, flirt with the new neighbour, not because we imagine the consequences of doing so, but because we are driven by instincts of fear, anger, hunger, or sex. Much of our learning, too, is based on ritual, or what our parents think is good for us, rather than on our own imagining of our futures. But mental time travel goes beyond instinct and learning by providing flexibility, allowing us to play out options and check their likely consequences. We can mind-wander into the future to see what might happen.
This is not an argument against evolution. The capacity for mental time travel itself surely evolved through natural selection, but provides much more flexible and rapid adaptation to the contingencies of a complex world than is provided by the slow mechanisms of genetic change. Learning provides a faster means of adapting to what life throws at us, but it is still a slow train. We plod through school and piano lessons, learn habits and rituals, but even these are sluggish and inflexible compared with the ability to conjure up scenarios, and fine-tune our lives.
Is mental time travel unique to humans?
In his poem ‘A Grammarian’s Funeral’, published in 1855, the English poet Robert Browning wrote: ‘“What’s time? Leave Now for dogs and apes! Man has Forever!”’ The idea that mental time travel, along with the concept of time itself, is peculiar to humans has been proposed by many, including Thomas Suddendorf and myself. Certainly, we humans seem obsessed with time. Events located in time weigh heavily on our conscious lives. We reminisce about the past, glorying in real or imagined triumphs, or regretting past mistakes. We dream about bright futures, vacations in the sun, or potential disasters. We are ruled by clocks, calendars, diaries, appointments, anniversaries—and taxes. We measure time on scales ranging from nanoseconds to aeons. Perhaps it’s all a bit much, and we should heed the advice of Buddha and try to live more in the present, like Browning’s dogs and apes.
Again echoing Browning, the German psychologist Wolfgang Köhler suggested that even our closest non-human relative the chimpanzee is, like Clive Wearing, stuck in the present. Köhler happened to be working at a primate research facility maintained by the Prussian Academy of Sciences in the Canary Islands when the First World War broke out. Marooned there, he occupied his time studying the behaviour of nine chimpanzees contained in a large outdoor pen. His work is famous for showing that chimpanzees are intelligent, and sometimes solve mechanical problems through the use of insight rather than mere trial and error. Köhler nevertheless concluded that, for all their problem-solving skills, chimpanzees had little conception of past or future.
Nevertheless, the idea that only humans are able to travel mentally in time, and imagine past and future events, is open to challenge, not least by a male chimpanzee called Santino in Furuvik Zoo in Sweden. Santino likes to collect stones and throw them at visitors. He gathers them well in advance of visitors arriving, and hides them so the visitors won’t see them. It is difficult to avoid the impression that Santino is planning a specific future event, perhaps even seeing it in his mind’s eye as he gleefully stockpiles his ammunition. Santino is not alone. In his book The Descent of Man, Charles Darwin described how he encountered a baboon at the Cape of Good Hope who threw missiles at people and prepared mud in advance for the purpose. The stockpiling of missiles is also a characteristic of that other dangerous primate, Homo sapiens. According to the Federation of American Scientists, Russia has 4650 active nuclear warheads, while the US has a mere (but more mathematically pleasing) 2468.
It’s not just apes; even birds seem to show evidence of mental time travel. Clark’s nutcrackers conceal items of food in thousands of locations, and later retrieve them with remarkable, but not perfect, accuracy. Scrub jays also cache food, and experiments suggest that they remember not only where they have cached it, but also which items are stored in which locations, and when they stored them. For example, if they have cached worms and peanuts, they will retrieve the worms if given the opportunity quite soon after caching them, because worms are more palatable than peanuts, at least to the jays. But if there is a delay, they will prefer the peanuts, because the worms will have decayed and become inedible. This has been taken to mean that they remember the act of caching in enough detail to know what they cached, where they cached it, and when they cached it. A simpler explanation, though, is that they mentally tag each item with a ‘use-by date’, and so know how long ago it was cached, rather than remembering the actual act of caching.
They also seem to cache with a future event in mind. If they are watched by another jay while caching, they will often re-cache the food in different locations when the watcher is no longer present. They evidently fear the possibility that the watcher will later steal the food; although it takes a thief to know a thief—they will only re-cache if they have themselves stolen cached food. Further, when given a choice of food to cache, scrub jays choose not in terms of their present hunger but in terms of what food they will want to eat the following day—anticipating breakfast, in other words.
Similarly, orang-utans and bonobos have been shown to save tools not needed right now for use up to 14 hours later. Some groups of chimpanzees store hammers and anvils for years of use in cracking nuts. Tool-making itself can be taken as evidence for mental time travel into the future. New Caledonian crows make tools from twigs and bits of wire to solve mechanical problems. In some cases this may be a simple matter of improvisation to solve an immediate problem, rather than planning for a more distant future. Other examples, though, do suggest specific planning for future use. The crows carefully shape the leaves of pandanus trees for the specific purpose of extracting grubs from holes. Using their beaks, they taper the leaves to be wider at the end which is held in the beak and narrower at the end inserted into the hole. The birds choose pandanus leaves because they have angled spikes along one side, and these attach to the grubs so the bird can then pull them out. The making of these tools suggests meticulous planning. Not to be outdone by crows, chimps fashion sticks for fishing termites out of holes, and spears for plunging into the hollow trunks of trees to extract bushbabies, which they then eat. One colony of chimps uses tool sets of up to five different stick and bark implements to extract honey from hives.
In all such examples, though, we cannot be sure that animals are truly travelling mentally in time, envisaging past or future events. It is often possible to account for what looks like mental time travel in a bird or a chimp in terms of instinct or habit. In birds, for example, the caching of food is instinctive, although it may be modified by experience, as in the case of the scrub jays re-caching their food after being watched by a potential thief. And even re-caching may be the outcome of a learned association between the presence of the thief and the subsequent loss of the cache, and need not imply actually envisaging a future theft. Tool-making industries among chimps may be the result of trial and error rather than planning, and passed between generations without any specific imagining of a future event. We humans learn lots of complex things, like reading or playing the piano, often without any conscious sense of what future it will bring.
Future-directed behaviours can be purely instinctive. Every year, Canada geese migrate south, in their distinctive V-formation, to escape the bitter northern winter. Some even reach Auckland, but there is no suggestion that they envisage the delights of New Zealand’s ‘most liveable city’ before they take off. In this they differ from the Canadians themselves who migrate to Florida or Hawaii, no doubt in pleasurable anticipation of what they will find when they get there. Instinct alone can drive remarkably complex behaviours, from the making of dams, nests, or even spiders’ webs to elaborate courtship rituals. Such activities are geared to future survival, but do not depend on mental travels through time.
Psychologists and ethologists have often reminded us to be careful when attributing human-like thoughts to animals. The English ethologist
Conwy Lloyd Morgan, who had studied under Darwin’s colleague and advocate Thomas Henry Huxley, famously established what has become known as Morgan’s canon:
In no case may we interpret an action as the outcome of a higher mental faculty, if it can be interpreted as the exercise of one which stands lower in the psychological scale.
The canon was declared in 1894, but ten years later the famous case of Clever Hans came as a salutary reminder. Clever Hans was a horse, and seemed able to answer complex questions by tapping a front hoof. When asked ‘What is plus ?’ he stamped his hoof nine times, paused, and stamped another ten times, apparently indicating that the answer was . When asked a person’s name, he would laboriously tap it out letter by letter, with one tap for A, two taps for B, and so on. Professor Carl Stumpf of the University of Berlin, a leading psychologist, was convinced of the horse’s genius, until one of his students, Oskar Pfungst, showed that Clever Hans was actually responding to subtle signals, given by his trainer, as to when to stop tapping. The trainer himself apparently did not realise that he, and not Clever Hans, was generating the answers.
The canon, also known as the principle of parsimony, has understandably been aimed at the idea that animals might be capable of travelling mentally in time. But there is also an uncomfortable sense that parsimonious explanations may serve to underestimate the intelligence of our animal cousins, and help preserve our human assumption of lordly superiority. The Bible gives added encouragement, as in the Eighth Psalm:
What is man, that thou art mindful of him . . .?
For thou hast made him a little lower than the angels,
and has crowned him with glory and honour.
The Wandering Mind Page 4
