What Good is Behavioural Science?

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Written by Cahal Moran, Rethinking Economics Support Team

As an economist who has moved into behavioural science, I find myself straddling two disciplines which have attracted public ire in recent years. Readers of this blog will surely be aware of popular critiques of economics, but may be less familiar with behavioural science and the challenges it has faced over the past year. In this post I want to give and overview of the contributions of behavioural science to our understanding. I will first consider whether behavioural science should be considered ‘the science of handwashing’, then move on to more exciting topics which people are less likely to have heard of. Specifically, I am going to discuss the role of habits, beliefs, poverty, and emotions in decision-making.

Coronavirus Challenges

Behavioural science is a new term which captures an idea which has been in the air for some time: using elements of economics, psychology, neuroscience, biology, and more in a quest to understand human behaviour and wellbeing. It has found its most famous expression in Nudge: a way of steering people towards better decisions without significant infringements on their liberty. One example would be changing the default option on a pension plan to increase saving by individuals – they are still free to opt out, but as a higher contribution is the default, in practice many people do not. Nudging has had many successes including reductions in energy usage, improved health outcomes, improved health and safety, and increased tax compliance. Owing to this success, behavioural science has spread across the globe over the past decade, with the number of university departments and programmes increasing and the key ideas behind it finding applications in the public, private, and third sectors.

It’s clear that with regards to covid-19, behavioural science has been of secondary importance compared to the work in medicine and especially in finding a vaccine. Still, when the pandemic hit the UK Government claimed that it was utilising behavioural science in its policy. They stressed that they didn’t want to lockdown too early because of the potential for ‘lockdown fatigue’ to set in, instead emphasising nudges to increase handwashing, reduce handshaking, induce people to stay at home voluntarily, etc. Though people surely do fatigue from repeated exposure to the same messages, it was unclear where this generalised and vague claim that people would stop adhering to (legally enforced) lockdown measures came from. This sparked a letter from hundreds of behavioural scientists – which was signed by many of my colleagues – asking what evidence base from behavioural science supported the Government’s claims.

Unlike the UK Government, behavioural scientists proceeded to engage in a wave of introspection about what their discipline, properly represented, could offer during the crisis. One review article quickly produced in early March argued that behavioural science could contribute directly in seven ways. For example, providing information about handwashing is not enough; sanitiser must be attractive and in hard-to-miss locations. Isolation is likely to have serious impacts on peoples’ mental health and well-being, so efforts to increase social contact virtually, especially by reaching out to vulnerable groups, are of paramount importance. Credible communication is equally important, effecting public-spirited behaviour through communication of positive norms – as is reporting health risks accurately.

Much of this sounds eminently sensible and would have undoubtedly been welcome in the UK, especially the part about credible communication. The well-being of the vulnerable has also been hugely undervalued during this pandemic. But I can’t escape the feeling that this advice is mostly refined common sense. What I want to do for the rest of this post is to provide a few examples of insights from behavioural science that I think are not obvious to most people, and which get at some of the most interesting forces underlying our behaviour. I am especially interested in areas where concrete links to biology can be established, and in my opinion the most credible studies emerging out of behavioural science use physiological measures, which are less prone to manipulation.

Automatic and Deliberative Behaviour

A key assumption of much of behavioural science is that there are different decision processes for different types of decisions Many readers will be familiar with Daniel Kahneman’s System 1 vs System 2 model of behaviour, detailed in his bestseller Thinking, Fast and Slow. System 1 is the automatic part of your brain: the part which knows that 2 + 2 = 4. System 2 is the more deliberative part of your brain, the part which has to work out 24 x 37. System 1 and system 2 are a model designed to understand behaviour and don’t necessarily correspond to literal regions of the brain, though as we will see there are some brain regions generally considered more effortful and reasonable, while others are more instinctive.

We tend to use system 1 more for an obvious reason: it’s much quicker and easier. For instance, it’s remarkable quite how much of our behaviour is driven by habit, which is largely a system 1 phenomenon. We like to think of ourselves as conscious agents, making decisions – and this has been the dominant approach in economics for a long time, too – but the reality is that we are on autopilot most of the time. According to one paper on the topic, “approximately 45% of everyday behaviors tended to be repeated in the same location almost every day”. Many people report the experience of having got up, showered, dressed, eaten breakfast, even commuted to work – all without truly registering that they’re up and active.

It seems we respond to cues in our environment that we have learned to associate with particular behaviours and therefore rewards. We learn habits as our brain releases dopamine neurons into specific regions, programming our reward system into continuing those same behaviours. This is not just observed in humans, so it clearly has a strong evolutionary grounding. There are obvious advantages to doing things automatically – as the same paper puts it, “without habits, people would be doomed to plan, consciously guide, and monitor every action, from making that first cup of coffee in the morning to sequencing the finger movements in a Chopin piano concerto.” Habits allow us to act without thinking, and in doing so they speed up our behaviour while simultaneously freeing up our minds to think about harder stuff.

On the other hand, this automaticity means that changing behaviour can be extremely difficult when the behaviour is driven by a habit. Naturally, one of the best ways to change a habit is by changing the context and therefore the environmental cues that drive the habit. We saw in early lockdown in the UK that many people took up exercise as it was one of the only (legal) ways we were allowed to leave the house. From personal experience, this seemed to go from a promising start with everyone exercising; to people staying in their gym kits but sitting around; to people just sitting around in the normal clothes and finally admitting they had given up on exercise. Although evidence is still tentative, it does seem there was an initial surge of interest in exercise, followed by a gradual tailing off, with the level remaining higher than before. This is a limited effect for such a dramatic change in context and speaks to the difficulty of changing habits.

It shouldn’t be concluded that System 2 is any less stubborn, though. An interesting paper on beliefs noted that peoples’ brains have an incredible power to filter out inconvenient information. This happens most obviously in politics, where there has long been evidence that people judge information that doesn’t fit their prior beliefs as less credible than that which does. Information that climate change is worse than previously thought will be ignored by those who deny it and incorporated by those who do believe in it. The converse is true for information that climate change is going better than previously thought, which is ignored by those that believe in it and incorporated by those that deny it.  This ‘confirmation bias’ doesn’t reduce with education or exposure to information, either.

Beliefs are an area which has been neglected by not only standard economics but by its behavioural variants, too. In a sense, beliefs cut across the ‘rational/irrational’ dichotomy, since the way our ‘rational’ brain processes information can be entirely contingent on the views of our ‘irrational’ brain. A valid question to ask is why do we hold beliefs? and there are a few answers. One is that the world is extremely complex and there’s so much we don’t know that we have to have some belief system to work under. Another is that beliefs can act as a commitment mechanism – to complete a project (for instance, a blog post that is much longer than you planned and has dragged over into 2021) one has to be slightly deluded about how important it is. One intriguing suggestion from this literature is that a degree of over-optimism, even though it may be technically delusional, is required to have a stable level of well-being and to engage in any activity at all. In essence, beliefs enable us to both understand the world and function within it.

Choice, Rationality, and Scarcity

Many readers will be familiar with the so-called Marshmallow Test, an experiment in the 1960s which gave children the choice of whether to eat a marshmallow placed on a table in front of them, or to wait until the experimenter returned to the room and receive two or more marshmallows. Most children struggled, but a good number waited; this was expected. The surprising finding was that, 20 years later, the children who waited for the marshmallows seemed to have better life outcomes in terms of health, education, and income. This became a beloved lesson in the virtues of patience, and the finding has clear political implications because children from richer families were consistently shown to be more patient than those from poorer families. Poverty, or so the story went, could be partially addressed if only the poor were more patient.

Though the marshmallow test managed to avoid being an outright crime – thus surpassing many other early psychological experiments – it has since been substantially caveated. One 2013 study had the experimenter promise to bring an art kit back, then either follow up or leave the child waiting, all before the regular marshmallow test. The children who’d had more reliable interactions with the experimenter beforehand were subsequently more likely to wait for the second marshmallow, suggesting the outcome of the experiment is less about individual self-control than about the reliability of the environment.

A 2016 study complemented this by monitoring the vagus nerve, a biological measure of calmness and so plausibly ‘rationality’, and also split the sample into rich and poor. For richer children, increased calmness (reduced vagal tone) was correlated with patience; for poorer children it was correlated with impatience. One interpretation of these findings is that poorer children are ‘impatient’ for a very good reason: they inhabit an uncertain environment where promises will not be kept and they have to take what’s in front of them. When you’ve been falsely promised many times before that you will get a birthday present or even a meal, it is ‘rational’ not to believe that the experimenter will not come back with the marshmallow.

This interpretation is in line with other evidence showing that poverty itself has an impact on peoples’ cognitive capacity. The theory is that the poorer one is, the less ‘cognitive bandwidth’ one has to think about issues outside of financial and physical survival – including, but not limited to, planning for the future. One study which looked at Indian farmers before and after a harvest showed that their IQ declined by one standard deviation, about as much as the difference between someone with a degree and someone without. Work by Sendhil Mullainathan has showed that prompting people with stories of financial distress reduces performance in an IQ-style task among poor people, but not rich people.

Economists, being economists, have taken to calling his a ‘poverty tax’, and there is some biological basis for it. Naturally, not eating as much as you should reduces your energy all round, making it more difficult to plan, work or do anything. But even for the well-fed, stress diverts glucose from the frontal cortex, the area most associated with careful planning. Your brain is physically less able to think systematically, or to think about anything other than the here and now  – and for good reason, because the here and now is all that matters when you’re under duress.

Neuroscience, Emotions, and Behaviour

This leads me neatly into a neuroscientific finding that is relevant for behavioural science: the relationship between emotions and decisions. One common belief is that emotions contrast with reason: we say someone is being ‘emotional’ when we believe they are acting unreasonably. The standard model of decision making in economics has no room for emotions whatsoever, and even behavioural economics treats them as an afterthought. Yet modern neuroscientific evidence shows that emotions are what drive decisions, to the extent that those whose ability to experience emotions is neurologically impaired are unable to make decisions altogether.

This is known as the Somatic Marker Hypothesis, developed by Antonio Demasio and his colleagues in the early 1990s. He studied patients who had damage in specific regions of their prefrontal cortexes which didn’t seem to affect their capacity for logical thought, but which significantly damaged their ability to ‘feel’. He ran an experiment where these patients were required to play a simple game which required them to select cards from different decks, winning rewards for better cards. Some of the decks yielded less, on average, than others. What Demasio showed was that while patients with fully functional brains selected less from these decks over time, those with emotional impairment could not make such a decision, continuing to sample from the bad decks.

It seems that we often make decisions by developing an emotional attachment to a particular outcome. Demasio’s explanation was that we link an outcome to the emotion we experience when it happens by envisioning the outcome occurring in our heads. This prevents us from continuing to draw cards from a bad deck because of the disappointment, annoyance, or sadness that we feel when we get a low card. If we cannot link potential behaviours with emotional outcomes, we lose the ability to steer our behaviour in a desirable direction. While it may be the case that being too emotional, or experiencing certain types of emotions, can lead us to make bad choices, not experiencing emotions at all can lead to the same thing.

There is a widespread understanding of emotions as a heuristic which provides information that we use to make our decisions. For example, a sudden loud noise may cause fear before we even know where it’s come from – and for good reason, because this fear prepares us to act fast if necessary. The behavioural economist George Loewenstein and his coauthors, in a paper literally titled Risk as Feelings, have argued that peoples’ attitudes towards risk are directly driven by emotions rather than cognitive evaluations, as they bypass the cognitive parts of the brain. Images of particular outcomes evoke strong feelings, which leads to a decision based on those images. Of course, this has its downsides: it seems to be invariant to the actual chance something will happen, which explains peoples’ disproportionate reaction to low probability but vivid events such as terrorist attacks or winning the lottery.

This link between emotions and decisions has been tested directly by stimulating areas of the brain associated with particular emotions. People can be given a sense of foreboding through direct stimulation of the amygdala, a part of the brain associated with fear and anger. One study found that stimulating the pre-frontal cortex can increase self-regulation, while another found that stimulation of the medial prefrontal cortex increases gratitude and therefore effort on an experimental task. On the more extreme end, frontal lobotomies appear to reduce the capacity to experience anxiety, or at least to utilise that anxiety to plan, making patients impulsive and risk-taking. (If you’re worrying about potentially Orwellian implications of these findings, check out the work of Robert Sapolsky, who has used them to argue for the exact opposite).


Behavioural science certainly has its challenges and limitations – for example, in the ethics of influencing peoples’ decisions. However, in my opinion it encompasses far more than ‘the science of handwashing’. Hopefully this post has given an overview of some areas where behavioural science has interesting things to say about how our minds work and why. It is increasingly linked to neuroscience and biology, which makes its theories of behaviour more empirically grounded. This post has also shown how we can use behavioural science to shed new light on issues such as poverty, health, and political polarisation. Overall, behavioural science is a valuable tool for any social scientist seeking to understand the human condition.

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