Kitabı oku: «Emotional Rollercoaster: A Journey Through the Science of Feelings», sayfa 2

the joyful brain

In his ecstatic state the man who received the telegram would not have been the ideal person to carry out a task involving careful analysis and precision because our mood can change the way we think. When we feel any emotion strongly enough, whether it’s fear or ecstasy, we tend to make decisions without processing information as deeply. Instead we rely on heuristics or stereotypes in our judgements.

A standard psychological test involves giving people a paragraph describing another person. After a delay they are asked questions about the person. If they are experiencing a strong emotion at the time they will rely on stereotypes triggered by certain words in the passage rather than on the actual information. This does have advantages in terms of efficiency which might be essential in a time of crisis. It might be unfair to assume that a man wearing torn clothes walking behind you down a dark alleyway is dangerous, but if that brief moment of anxiety causes you to quicken your pace so that you reach the main road faster, then even if he turns out to be harmless you haven’t lost anything by speeding up. Were you to slow down while you considered whether there was in fact anything suspicious about the man’s behaviour or whether you were unfairly generalising on the basis of his clothing, you might put yourself in danger. Nevertheless it is not the case that strong emotions always lead to a decrease in accurate reasoning. Emotions tend to be seen as irrational urges which interfere with effective decision-making. Research has shown, however, that in certain circumstances, feeling good can change your thinking in such a way that you make better decisions, particularly if those decisions necessitate creativity.

You are given a standard white candle, a box of drawing pins and a book of matches. Your task is to attach the candle to the wall and light it in such a way that the wax won’t drip onto the floor. When people were given this task in a laboratory after their mood had been manipulated the results were striking. One group had been given a comedy to watch before the task while the others saw a more serious film. Three quarters of the group who had seen the happy film found a workable solution, compared with a measly 13% of those who had seen the serious film. The solution to the task, incidentally, is to use some drawing pins to fix the drawing pin box to the wall as a ledge for the candle. Then you light the candle with the matches and the box successfully catches the drips.

Dr Alice Isen, a psychologist at Cornell University, has conducted years of experiments in this area, finding that mild happiness can improve performance in everyone from children to doctors. She finds cunning ways of making one group of people feel slightly happy – giving them money, telling them they’ve done unusually well on a task or simply providing fruit juice and biscuits. Compared with another group who hadn’t had any reward, the happy group were significantly better at thinking up unusual word associations. In another experiment doctors were given a bag of sweets to cheer them up before they made a diagnosis and extraordinarily this resulted in a better diagnosis where they took more information into account. This had nothing to do with them putting in extra effort because they were happy; instead there appeared to be something qualitatively different in their thinking. When people feel happy they seem to consider problems from more angles.

Joy allows people to think optimistically and to remember other times when they were successful, as well as allowing them to focus on the task at hand. Your negotiation skills even improve when you feel happy, so the time to ask for a pay-rise is not when you’re feeling fed up with a job, but when you’re feeling good.

If we turn to the chemistry of what’s happening in the brain there might be an explanation for these processes. Dopamine is just one of hundreds of neurotransmitters or chemical messengers in the brain, but we know more about it than any of the others. The cells that produce dopamine are only found in a few areas of the brain, mainly in the brain stem, but it has effects in many other areas. Food, sex and drugs all release dopamine, producing feelings of pleasure, but only for a limited time. Like all neurotransmitters dopamine is a chemical that allows one neuron or nerve cell in the brain to communicate with the next and in this way messages are passed between the millions of neurons in the brain. Dopamine is released when we feel joyful and it is these dopamine levels that might affect the way our thoughts are processed. Alice Isen suggests that the release of dopamine into a part of the brain called the anterior cingulate region might help us to switch perspective. Seeing things from another viewpoint is a key component of creativity and we might actually find this easier if dopamine is helping us along while we explore ideas. The same could apply to negotiation; to bargain successfully it’s necessary to see another person’s perspective along with your own. Then you can encourage them to agree to a solution that is beneficial to you.

In the 1950s two scientists, James Olds and Peter Milner, were experimenting with rats to see whether they could teach them to do simple tasks like pressing a lever. They discovered that if you put an implant into a certain part of a rat’s brain – the hypothalamus – and then apply a weak electric current, the rats actually like it, or rather they love it; if they were provided with a lever by which they could control the electric current themselves, the rats would press the lever about 2,000 times an hour, for hours at a time. If the rats were given the choice between feeding or pressing the lever, they would starve themselves rather than miss out on the current. This only worked if the current was applied to the part of the brain associated with dopamine release; if the rats were given a drug which blocked the action of dopamine they lost all interest in the lever. The reward system in a rat’s brain had been discovered. It is assumed that humans have a similar system. Could brain stimulation explain the joyful feelings that the Russian novelist Dostoevsky said he felt preceding his attacks of epilepsy? He described it as ‘a feeling of happiness such as it is quite impossible to imagine in a normal state and which other people have no idea of.

In a more unpleasant experiment an electrified grid was used which gave a shock so painful to a rat’s feet that if food were placed on the other side of the grid a rat would die of starvation rather than go through the agony of crossing. However, the rats would cross the grid to get to the dopamine pedal. It seems they were prepared to do anything to get that rush.

Drugs such as cocaine, nicotine, cannabis and amphetamine all raise the concentrations of dopamine in the brain, either by increasing the amount released or by blocking the mechanism that reabsorbs the dopamine, limiting its effects. Either way the person ends up with more dopamine. It’s the same process as the one that happens when the rats stimulate their hypothalamus. The more addictive drugs – cocaine and heroin – release more dopamine.

It has now been discovered that even the anticipation of taking a drug can release dopamine. The problem is that in addiction this anticipation is experienced as a craving, which, despite the release of dopamine, isn’t pleasurable. The power of dopamine could explain why addicts will sometimes risk losing their jobs and homes, even their families, in order to get another fix. As the brain adjusts to the new dopamine levels, the drug is needed purely to continue functioning. This is known as the dopamine theory of addiction, but what it can’t explain is why so few people become addicted. Only 10% of people who use cocaine become hooked. Likewise only 10% of the American soldiers who regularly took heroin in Vietnam took it again once they were back home. This implies that a person’s situation plays a big part in addiction.

A Canadian psychologist Bruce Alexander has lent weight to this idea with his creation of a luxury rat park. He trains rats to become addicted to a dopamine pedal, but then instead of placing the pedal in a bare cage, he installed it in the luxury rat park where there are jogger wheels, plants, warm nests, nice food, plenty of space to run around and even mountain scenery and streams painted on the walls. Once rats were in here and were occupied and presumably more contented they barely touched the dopamine pedal, in contrast to the caged rats so desperate to get to the pedal that they would starve themselves in order to reach it. This could provide part of the explanation for the fact that so many people who try drugs don’t get hooked. Provided people have alternative stimulation in life they might not become addicted.

Another possibility is that some individuals have fewer dopamine receptors than others. With fewer receptors you need to take more drugs to derive the same pleasure as someone else. The level of addiction in rats has been successfully altered through manipulation of the number of dopamine receptors.

More radically, there is a suggestion that addicts are born with a gene which stops them from experiencing joy in the same way as other people. The idea is that some people are born with a difference in one particular form of the dopamine receptor gene. The gene controls the way that dopamine is released into the brain and comes in two forms, a common type and a rarer version known as Al. A team from UCLA in the United States led by Ernie Noble found that the same gene seems to be implicated in addiction to cocaine, heroin and nicotine, and even eating disorders. He believes that those with the Al form of this gene don’t feel the same joy from something like sitting on a beach watching a sunset or seeing a live concert, however brilliant. By taking drugs or drinking alcohol they can bring their dopamine up to the same levels as everybody else. This new pleasure leads them to become addicted to the experience. Not all addicts have the gene, but those who do find it harder to overcome their addiction. Even with smoking, people who repeatedly attempted to quit without success were found to be more likely to have the Al form of the gene. With a team in Australia Noble tested his theory during the treatment of alcoholics. Patients were either given a placebo or a drug called bromocryptine which activates your dopamine receptors. They found that with the people possessing the Al form of the gene the bromocryptine reduced their cravings almost completely. Moreover, they felt less anxious and remained in the treatment programme for longer than those who had the more common form of the gene. Once the bromocryptine had rectified their dopamine levels, the desire for alcohol faded. This gene won’t explain all cases of addiction; Noble believes that about half of drug addicts might have it, suggesting that they might benefit from a pharmacological approach to treatment, while others might find counselling more effective. He hopes that in the future treatments for addiction could be targeted according to a person’s genes. According to his theory as many as 30% of the population might have the gene, preventing them from experiencing joy. This, he thinks, might lead some people to seek risky pursuits, in the hope of feeling something.

If this is an accurate assessment then it is cause for some concern, but not everyone agrees with Noble’s theory. Some attempts to replicate his results have ended in failure. It might be an oversimplification to suggest that just one gene is involved; there could be lots of different genes contributing – either in relation to a specific drug or general addictive behaviour.

The curious thing about joy is that if you ask people whether they would like to have the human equivalent of the rats’ joy lever, as the Harvard philosopher Robert Nozick did in a thought experiment in 1989, most people say no. He asked them to imagine a machine which can produce whatever set of feelings you desire. You can experience success, pleasure or friendship in any combination and for as long or as short a time as you want to. The only catch is that although you would remain healthy you would have to spend the rest of your life attached to the machine. Despite the guarantee of feeling good for the rest of their lives, coupled with variety to dispense with boredom, people still say no, believing that however the machine made them feel, they wouldn’t be truly happy.

the joy of exercise

When James was sixteen years old he took part in a crosscountry championship. Near the end of the race he was in fourth place, but knew that he was too tired to make the pace needed for him to win. Then something strange happened. ‘I was feeling really exhausted, but in a space of two minutes I moved into this rhythm and this beat where I felt absolutely invincible. I ran forward, took over first position and sprinted to the finish. I remember at the time I couldn’t talk to anybody; I just had to be on my own. There was just this sense of something in my body rewarding me – almost a chemical-like feeling of power.’

James had experienced something which many athletes find elusive – an exercise high. Some people exercise vigorously for years without achieving even one, but when it happens the theory is that beta-endorphins are key. Endorphin is short for endogenous morphine, i.e. morphine made by your own body. They are the body’s natural tranquillisers, which we release when we are in pain. Like morphine, they can also cause pleasure; the pain remains, but you don’t care anymore.

Is it possible that these endorphins could actually bring feelings of joy? There’s a physiological mechanism called the blood-brain barrier that protects the central nervous system by preventing most substances from crossing from the bloodstream into the brain tissues. The problem is that it’s not known whether the endorphins released into the bloodstream during exercise can actually break through the blood-brain barrier in order to have their effect on the brain. Exercise highs are hard to study systematically because it’s not an effect that can be easily quantified – who is to say what constitutes a high and what doesn’t?

It does seem, however, that exercise can affect the brain, even if the results are somewhat milder than a full-blown high and this might enlighten our understanding of the way both our minds and the rest of our bodies influence our emotions. Two or three short sessions of exercise a week can make people feel demonstrably happier, particularly if they are depressed initially. Some GPs already prescribe exercise for patients with mild depression with some success. There have even been studies showing that exercise can be as effective as anti-depressant medication. As well as the suggestion that this is due to the release of beta-endorphins there is also a theory that, like recreational drugs, exercise might cause the release of dopamine, hence we feel good.

Although research into the effect of exercise on mood might sound straightforward it’s not without its problems. For example, in some studies comparing one group who are prescribed exercise with a group not prescribed exercise, the people taking part were allowed to choose which group to be in. This inevitably introduces a bias – the people choosing exercise are likely to expect to see more positive results than those who avoid exercise. Studies have tended to allow a choice because it would be hard to persuade someone who had always detested exercise to take part in a study which might compel them to join a class. But if exercise could be shown to improve the mood of these people then it would be a powerful tool indeed. Yet another problem for the designers of these comparison studies is that factors other than the exercise itself might affect the group taking the classes. Participants might begin to feel better simply because they enjoy belonging to the group which goes to the special class. The fact that they are trying a new method of alleviating their depression might make them feel more hopeful and even the instructor’s expectations that they feel better after a session could make a difference. Any of these could have a slight improvement on a person’s mood before a single step of exercise has been done.

Despite the methodological difficulties there is some good evidence that exercise can make you feel good. The world’s first Professor of Psychopharmacology, Hannah Steinberg, has suggested that the effect of exercise could be harnessed as a treatment for drug addiction. Just as addicts use methadone as a substitute for heroin, Steinberg believes the next step might be to use exercise as a substitute for methadone, helping the brain to provide its own alternative opiates. It’s an intriguing idea, but she found it hard to persuade anyone to conduct trials.

A Danish study of just eight people addicted to drugs or alcohol found that exercise did seem to help them resist their addiction while they remained in hospital, but once they left they dropped the exercise programme and five out of the eight resumed their addiction. This study is so small of course that there could be other factors at play. The problem with using exercise in a deliberate attempt to induce feelings of euphoria is that even in experienced runners a high isn’t achieved every time. There’s also the question of whether the intensity of high could ever compare to that induced by drugs. Even if it worked on some occasions, however, it might be useful as one part of a treatment programme, with the added advantage that exercise is free and healthy.

However, it still isn’t clear whether improvements in mood after exercise are caused by the release of endorphins. People feel better after exercise even if they have been given a drug which blocks the production of beta-endorphins altogether, suggesting either that other neurotransmitters might take the place of endorphins when they are blocked or that there are other factors at work. A person might feel better after an exercise class because they are pleased with themselves for having made the effort, or perhaps they enjoy seeing themselves become fitter, or simply feel satisfied at having mastered a new routine. These could all feed through to a person’s self-esteem.

Finally there is the social interaction. If a person is at home feeling depressed, then visiting the gym with other people might provide a break from that isolation. If you use a drug to block the production of beta-endorphins, the improvement in mood after exercise still occurs, suggesting that endorphins might have nothing to do with the process.

In the Department of Kinesiology at University of Wisconsin-Madison there are treadmills, weight machines, exercise bikes, free weights and a swimming pool. While human guinea pigs pump iron every flutter of their heart can be measured. Outside there is even an arboretum where volunteers cut down the undergrowth while wearing transmitters which allow the scientists indoors to measure their heart rates. After they’ve finished the work, their levels of anxiety and depression are measured. With the help of this equipment and a team of volunteers, Professor William Morgan has developed a theory which might explain why exercise can make you feel happy – he calls it the distraction hypothesis. It is appealingly simple; exercise makes us feel good merely because it distracts us from the worries of the day. He found that although people do experience a decrease in anxiety as a result of vigorous physical activity, the effect soon wears off and within twenty-four hours you’re back to where you started. Therefore regular exercise could be a way of topping up your joy and keeping a lid on anxiety. Too much exercise, however, can have the opposite effect. In experiments where swimmers progressively increased their training sessions from 3,000 metres a day to 12,000 metres a day, the athletes gradually became more depressed. Once they began to decrease the distance they swam, their mood slowly returned back to normal.

There is some more good news for people who prefer to sit still. Professor Morgan also found that when he asked people to sit in a quiet room in a comfortable old leather armchair or lazyboy, as he calls it, for the same length of time as an exercise session, they felt just as good afterwards.

A final theory of why exercise might make you feel good is the thermogenic hypothesis – the idea that you feel happy after exercise because your body temperature has increased and that it is this high temperature which is responsible for the release of beta-endorphins, which in turn make you feel good. Not surprisingly, research in this area began in steam baths and saunas in Scandinavia. In one study back in 1972 the volunteers who took part had a twenty-minute sauna followed by a ten-minute shower for which they were paid in cash and in beer. Before and after the sauna the mood of the volunteers was measured. Beforehand two of the twenty male volunteers had warned the experimenters that they didn’t like saunas and indeed four people did find the sauna so stressful that they had to be let out early. However, overall people did feel less anxious after the sauna, but so did the control group who had undressed, sat waiting on a bench for twenty minutes and then had the ten-minute shower.

More recently William Morgan’s team have tried to determine whether it’s the exercise per se or the rise in temperature which makes people feel good after exercise. He found that if the whole body is heated mood can improve for up to twenty-four hours and in the bloodstream at least, levels of beta-endorphins rise. The team have come up with ingenious experiments in an attempt to establish the answer such as getting one group to exercise dressed in everyday fitness gear while another group exercised clad in warm clothes, a hood, gloves, a surgical mask and two blankets. Despite the rise in body temperature, not surprisingly the hot group ended up feeling more anxious than the others, rather than less. Another approach is to prevent the exercise from increasing the body’s temperature by lying in a cold bath for half an hour before exercising. It was found that if a person’s body had been cooled beforehand their temperature remained low and they felt no better after exercise, whereas the people whose bodies had not been cooled did feel happier after exercise, suggesting that it could be the rise in temperature, not the exercise itself, that makes people feel better.

Another way of testing this theory is to prevent body temperature from rising with exercise by doing that exercise under water, but when this was tried with scuba divers they still felt better afterwards, suggesting that it’s not the warmth that’s doing the trick. At the University of California Shawn Youngstedt and his team put volunteers on exercise bikes under water with their heads poking out above the surface. There was no improvement in mood after exercising, but the researchers do warn that this might have been due to the novelty of the task or anxiety caused by having their oesophageal temperature taken – a procedure involving the insertion of a tube up the nose and down into the throat. Other experiments have involved exercising while wearing a scarf filled with ice and even having a rectal temperature taken before, after and (somehow) during exercise. In this study anxiety did decrease after the exercise session, but perhaps the participants were simply relieved that it was over. So it seems that exercise can make people feel good, but we’re still a long way from knowing exactly why.