DO YOU prefer cake to oranges? Do you sometimes forget to wash your hands after using the toilet? If the answer is yes, then you are a normal human doing what comes naturally, even if this is not necessarily what is good for you.
Getting people to do what is good for them is notoriously difficult 鈥� just ask anyone who works in public health. Health officials spend their lives trying to persuade people to give up smoking, take more exercise and eat healthier food. In developing countries, persuading people to change their behaviour is key to reducing the ravages of AIDS, malaria, diarrhoea and other infectious diseases.
Their efforts are often in vain. A review of community anti-smoking interventions worldwide by researchers at the University of Vermont concluded that they had had virtually no effect (). A study for the Scottish Executive of international programmes to prevent alcohol abuse found much the same (). And a review by researchers at McMaster University in Hamilton, Ontario, Canada, of programmes designed to reduce unintended pregnancies among adolescents found that they, too, had been completely ineffective (British Medical Journal, vol 324, p 1426). Clearly, we need a new approach.
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Health promotion leans heavily on insights from late 20th-century cognitive psychology and the belief that our behaviour is driven by rational calculation. What it has yet to exploit is the revolution in brain science and psychology that has taken place over the past decade 鈥� and it is time it did. Neuroscience and evolutionary psychology can help us greatly in understanding and modifying human behaviour. They demonstrate that our decision-making is driven predominantly not by rationality but by emotions, which are seated in our ancient animal brain.
鈥淭he way we make decisions is driven more by emotions than rationality鈥�
Take the washing of hands with soap after using the toilet, one of the most widely disseminated health messages (see ). More than a million lives could be saved each year if people washed their hands at key times, because diarrhoeal and respiratory pathogens 鈥� the biggest child killers in the world today 鈥� are carried on people鈥檚 hands. Despite this, our studies in developing countries suggest that fewer than 10 per cent of mothers do this, and mothers in developed countries are often not much better. Evidently, teaching people about germs is not enough.
What our studies in Africa, Asia and Europe have shown is that people are much more likely to wash their hands if they are motivated to do so at a deeper emotional level 鈥� by disgust, or by the desire to conform to social norms and be respected by others, or to nurture and care for their offspring. In Ghana we found that people were failing to wash their hands because they did not perceive any contaminating matter on them: they did not see the yucky stuff, so they did not feel disgusted. So our job was to make people feel disgust, and we did this through a national campaign that included a television advertisement depicting a caring mother inadvertently contaminating her child鈥檚 food via her hands after using the toilet. After watching it, 58 per cent of the mothers we asked said they had changed their hand-washing habits.
There are many ways in which advances in brain science and psychology can help us change people鈥檚 behaviour. Firstly, it is important to recognise that the brain works by associating experience with reward or punishment. People become addicted to smoking because their brain comes to associate it with pleasure. The way to break this is to use strong emotional triggers. Hence the recent 鈥済ive up before you clog up鈥� anti-smoking campaign in the UK, which depicted a cigarette oozing fat. Likewise, if you want to get people to take up healthy habits, you have to associate them with strong rewards. So while the promise that running will make you healthy might not be enough to persuade people to take it up, the suggestion that it will make you more attractive as a mate could do the trick.
Secondly, evolution has programmed us to be lazy, to conserve energy where possible. So healthy choices have to be easy ones. Junk food is attractive because it resembles food that was rare and desirable in the environment in which we evolved: energy-dense, sweet and fatty. Nowadays it is available everywhere, and cheaply. Food policy should concentrate on making healthy foods equally easy to get hold of.
Thirdly, surprise is crucial. Emotions only kick in to interrupt a habit when the brain detects that an impending reward is noticeably greater or less than what it has learned to expect 鈥� think how you feel on finding a cockroach in a bowl of delicious soup. Health campaigns have to continually reinvent themselves and grab people鈥檚 attention.
Changing behaviour means understanding our deepest desires. To break unhealthy habits, campaigners need to target the emotions, because they are the decision-makers. Where the heart leads, the habits will follow.
