Born Liars (13 page)

Wegner believes that our feeling of free will is nothing but a trick of perspective – a deception practised by the brain. A conscious ‘decision' is merely a story we tell ourselves to explain what has happened
to
us, or what our bodies have already executed. This is a deeply contentious position, although many neuroscientists agree with him. There is certainly a huge amount of experimental evidence that our unconscious brain guides and determines many of the everyday decisions we think of as conscious ones. When you choose a brand of toothpaste or reject someone for a job you may be doing so for reasons of which you're completely unaware – the unconscious associations you have with a brand name, the job candidate's gender. What's certain is that you'll spontaneously come up with a plausible reason: the toothpaste's plaque-reduction system, the interviewee's lack of experience.

Two cognitive scientists from Sweden named Lars Hall and Petter Johansson devised an experiment that relies on a card trick they were taught by a professional magician. The researcher holds up two photographs, each with a different face on it, and asks the subject to choose the one she finds more attractive. The researcher lays both pictures face down and slides the chosen photograph over to the subject – except he doesn't. Using a sleight-of-hand technique he covertly swaps one picture for the other, so that the picture the participant ends up with is the one she
didn't
choose.
¹³
You might expect the subject to take one glance at the photo in her hand and protest to the researcher that this isn't the man she chose, and indeed in some cases that's exactly what happened. But in most trials, the participants didn't appear to notice. This alone would make the experiment interesting. The most telling part, however, came when the subjects who had accepted the ‘wrong' card were asked how they had made their ‘choice'. They unhesitatingly offered up elaborate explanations of what had attracted them to that person's eyes, hair, or bone structure.

One classic experiment was conducted in a park in British Columbia, Canada. A female assistant with a clipboard approached young men in the park and asked them to take part in a survey on creativity. After writing down their answers, she suggested that maybe they might like to discuss the results with her later, and wrote down her number for them. The researchers tallied how many of the men called her later and asked her out. The clever part of the experiment was that the researchers varied the situation the men were in when approached. Half of them were on a terrifying footbridge spanning a deep gorge. As these men talked to the woman they were holding tight to the flimsy handrail as the bridge swayed in the breeze. The other group of men were sitting safely on a park bench. The question the researchers were interested in was, which group of men would be more attracted to the woman?

You might wonder why on earth it should make a difference whether they were approached on the bridge or the bench; after all, it's the same woman. Yet sixty-five per cent of the men on the bridge called to ask the woman on a date, compared to thirty percent of the men on the bench. The reason for this is that the brain can pursue its mission to explain with a little too much zeal. When the men on the bridge took the woman's number, their hearts were pumping rapidly, they were perspiring, and a little short of breath. They would have recognised to some extent that these symptoms were down to their physical situation, but even so, they misattributed some of their arousal to attraction to the woman. The sense-making part of their brains had gone into overdrive and created a surfeit of explanation for what was going on. As a result the men became much more likely to tell themselves they had a crush on the woman, and more likely to call her afterwards. So there you are: if you want to ask a stranger out, wait until they're in physical danger and seize your moment.

Like our perception of the physical world, our perception of why we do things is a fantasy that collides with reality. This description would have made sense to Freud, of course, who believed that we are deceived about the nature of reality because we fundamentally deceive ourselves about who we are. We fantasise that we know what we want out of life when in reality we are divided into warring factions, each wanting something different. Amongst academic psychologists at least, Freud's ideas fell deeply out of fashion after he died. His arguments were based more on intuition than evidence, and his gothic vision of the unconscious as a realm of repressed sexual desires remains deeply idiosyncratic. But in recent decades, neuroscientists have concluded that he got at least two very important things right: our psyche
is
deeply divided, and our conscious actions
are
deeply influenced by sophisticated mental processes of which we remain unaware, day by day. All of us are engaged in an act of creative self-deception to maintain the fiction that we know why we do the things we do.

In 1960 a young graduate student called Michael Gazzaniga joined the laboratory of the great neurologist Roger Sperry. Gazzaniga was overjoyed to have landed a job under Sperry, who was the first to discover that the brains of some animals, including ours, are split into two systems, left and right, each with different responsibilities. If you stare at a fixed point in space, like a dot on the wall in front of you, everything to the left of the dot is projected to the right half of your brain, and vice versa. Each hemisphere receives nerve transmissions from the opposite leg and arm and picks up sound from the opposite ear. Nobody knows why the signals cross over – the official scientific explanation is pretty much,
they just do –
and in the normal brain it doesn't make much difference where the information lands because the connecting pathways between each half-brain are intact.

In 1961 Sperry got a call from a former colleague, the neurosurgeon Joe Bogen, who told him that he was about to perform a radical new operation on a patient suffering from epilepsy. Epileptic seizures always start in one part of the brain and then spread to the surrounding tissue. A minor seizure can spread to the entire brain, causing the person to lose consciousness, fall to the floor and writhe uncontrollably. To stop the seizure spreading from one half of the brain to the other, Bogen proposed a severing of the thick bundle of nerve fibres, known as the corpus callosum, that connects the two hemispheres. Sperry sent his protégé Gazzaniga over to Bogen's lab, to perform tests on the patient before and after the operation.

Given that nobody was quite sure what the corpus callosum was responsible for, or how the two halves of the brain interacted, Bogen's proposed operation was risky. But he knew Sperry had performed this operation on animals with no apparent ill effects, and he knew that his patients, some of whom suffered from severe, life-ravaging epilepsy, were desperate to try something. William Jenkins, a smiling, chipper forty-eight-year-old, had volunteered to be first to undergo the operation. Bogen had first met him when Jenkins was admitted to the emergency room of Bogen's hospital in the middle of a severe fit. Jenkins suffered frequent, punishing convulsions and dangerously sudden losses of motor control, which effectively prevented him from living anything close to a normal life, and he had been told there was no cure for his condition. He knew that Bogen's solution was something of a leap into the unknown, but he and his wife told the surgeon that they were eager to go ahead. ‘You know,' said Jenkins, ‘even if it doesn't help my seizures, if you learn something it will be more worthwhile than anything I've been able to do for years.' In February 1962, after practising the operation half a dozen times in the morgue, Bogen severed Bill Jenkins's corpus callosum.

It worked. Jenkins recovered strongly from the surgery and was soon feeling something like his old self again, his seizures greatly alleviated. But were there really no side-effects? Gazzaniga asked Jenkins to stare at a spot on a screen while he flashed images just to the right or just to the left of it. The images came and went quickly enough that the patient couldn't move his gaze, so when a picture of a hat was flashed just to the right of the spot, it was processed by his left hemisphere. When Gazzaniga asked, ‘What did you see?' Jenkins had no difficulty in identifying the hat. But if the same image was flashed on the left side of the spot, he didn't know what to say. The image was being processed by the right hemisphere, which doesn't have the power of speech.

It's not as if the right brain hadn't seen anything. Gazzaniga showed Jenkins a card with several images on it, and asked him to point
with his left hand
to the image that he had just flashed up on the screen. He had no difficulty doing so. The right hemisphere knew the answer – it could point – but was unable to communicate verbally. Normally, Gazzaniga realised, it could call out to the left hemisphere via the corpus callosum for help in finding the right word. But without it, nothing emerged from the patient's mouth. In another experiment, Gazzaniga blindfolded Jenkins and asked him to hold an object like a comb or a coffee cup in his left hand. If he held it in his right hand he had no trouble identifying it. When transferred to the left hand, he was literally at a loss for words.

Gazzaniga had fallen upon an insight he was to explore and develop for the rest of his career: we are not one, but two. The brain's hemispheres, left and right, operate as separate intelligences housed in one body. The left side deals with analytical and logical thinking and has the gift of language; anything to do with speaking or writing is dealt with here. The right side is illiterate and mute, but has its own magical powers.
¹⁴
It is much better at identifying
patterns
– at recognising categories, objects and faces, and enjoying music or art. The two systems work closely together, but are independent. With the messenger cut out, the inner division of the mind into two different entities was laid bare. Henry Jekyll had been on to something.

Gazzaniga went on to discover much more about how the parts of a split brain relate to each other. For instance, when they are no longer joined up directly, they can find new ways to co-operate. In one of Gazzaniga's experiments, a split-brain patient is asked to reach into a closed bag with his left hand, feel the object inside, and say what it is. The object is something easy to identify, like a pencil, but because the right brain is mute, the patient can't say the answer. The right hemisphere hits upon a cunning plan. As we've seen, most tactile sensations are cross-wired. But there is an exception: pain stimuli go to both hemispheres. The patient holds the pencil in his left hand with the point pressed hard into his palm. This sends a pain signal shooting into
both
parts of the brain. So now the left knows something, at least – there is a sharp object in the bag. Using this hint, it begins to guess. The patient speaks: ‘A pin, a needle, a pen?' The right hemisphere, which possesses the answer, helps out: it signals when these guesses are getting warmer by smiling or nodding. Very soon the patient announces the correct answer. It's a stunning example of neural teamwork. Even with the internal connection cut, the two hemispheres find a way of communicating by going via the outside world.

The brain's hemispheres can also fall out with each other, and violently. Some split-brain patients suffer from a condition known as ‘alien hand syndrome'. One hand, usually the left, takes on a life of its own, and a bizarre Punch and Judy show ensues. The neurologist Victor Mark of the University of North Dakota interviewed one such patient. When asked how many seizures she had recently experienced, her right hand held up two fingers. Her left hand then reached over and forced the fingers on her right hand down. After some back and forth she gave up and let both have their say, displaying three fingers with her right hand and one with her left. When Mark pointed out the discrepancy, she commented that her left hand frequently did things on its own. A fight ensued between the two hands, at the end of which the woman burst into tears.

Many similar cases have been recorded. The alien hand might pick up a ringing phone but then refuse to pass it to the other hand, or grab a shirt picked out by the other hand and place it firmly back on the rack. It often seems to be on a mission to disrupt the person's conscious intentions, dumping a glass of water into a bowl of cereal, unbuttoning a shirt that the right hand is in the process of buttoning, removing a cigarette the person has placed in his mouth with his right hand. One man recalled seizing his wife with his left hand and shaking her violently, while with his right hand he tried to come to his wife's aid. In several cases, the alien hand has reached for its owner's neck and tried to strangle him.

Hard as it is to conceive of, some scientists think it likely that left and right hemispheres, speaking and mute, are each conscious entities in their own right, with their own thoughts and moods.
¹⁵
This central division is made up of further divisions into hundreds of independently functioning, non-conscious modules, all capable in different ways of initiating behaviour or generating an emotion. They aren't necessarily designed to cohere. The brain wasn't built to a master plan, but has picked up different functions over millions of years, yoking them together imperfectly as it goes, like a royal palace that has been added to, altered and extended in different architectural styles, with the result an imposing but untidy sprawl that somehow works as a single building. It shouldn't be a surprise, then, that the brain's agents are sometimes at cross-purposes. Although the fully functioning brain does a pretty good job of maintaining the internal flows of information and keeping order, there is no all-seeing, all-powerful chief executive or president tasked with ruling over Jekyll's society of ‘multifarious, incongruous and independent denizens'.

We are familiar with the sense of internal conflict; most of us know the battle between desire and conscience all too well. In Ovid's
Metamorphoses,
Medea describes herself as being torn apart, ‘desire and reason are pulling in opposite directions'. In his novel
Solar
, Ian McEwan describes a mind in decision-making mode as a parliament or debating chamber: ‘Different factions contended, short- and long-term interests were entrenched in mutual loathing. Not only were motions tabled and opposed, certain proposals were aired in order to mask others. Sessions could be devious as well as stormy.' But, most of the time at least, I don't
feel
like an assembly of different selves (whatever that would feel like). I feel like me, and you feel like you, or at least I assume you do. Split-brain patients feel this way too. They have no sense of themselves as anything but whole. Even those suffering from alien hand syndrome only see the effects rather than sensing the cause. How is it that each of us feels like one person, with one mind, when in reality we are divided? More than ten years after his momentous encounter with William Jenkins, Michael Gazzaniga made another breakthrough that helps to explain how we keep it all together.