
âI WAS at a hospital the other night where I think there were actually a few coronavirus patients, and I shook hands with everybody, youâll be pleased to know. I continue to shake hands and I think itâs very importantâŠâ UK prime minister Boris Johnson, Downing Street press conference, 3 March 2020.
âSick Boris faces fight for lifeâ. Front page, Daily Mirror, 7 April 2020.
If a week is a long time in politics, a month is an eternity in a pandemic. In early March, few batted an eyelid at Johnsonâs handshakes. Now they seem reckless.
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żìĂš¶ÌÊÓÆ” of the prime ministerâs illness led many of the Twitterati to point out that the coronavirus âdoesnât discriminateâ. Wrong. It does â by behaviour. If you come into contact with an infected person, you may well catch it. If you donât, you probably wonât.
This is why behavioural science is absolutely central to our fight against the pandemic. Clearly, the hard biomedical sciences such as virology, epidemiology, immunology and pharmacology matter. But unless we also factor in the science of human behaviour â how real humans in the real world act and think â our understanding is incomplete, and our attempts to defeat the virus will fail.
Getting people to do what we want is notoriously hard, which is why governments around the world have been relying on behavioural scientists to inform their approach to the pandemic. Thereâs everything to play for, as Molly Crockett, a psychologist at Yale University, and her colleagues wrote in a recent paper on : âIn order to slow the coronavirus pandemic, healthy people must take basic steps to change their behaviour, and doing so has the potential to collectively save thousands if not millions of lives.â Get it wrong, however, and the effects could be disastrous.
Arguably, behavioural scientists have been prepping for a challenge like covid-19 for a decade. In 2010, the UKâs newly elected coalition government set up its experimental Nudge Unit within the Cabinet Office. The central idea, which was popularised in the 2008 book Nudge by Richard Thaler and Cass Sunstein at the University of Chicago, is that humans often make bad, irrational decisions but can be encouraged to make good, rational ones by changing how choices are presented to them.
âChanging peopleâs behaviours has the potential to save millions of livesâ
The classic example is membership of workplace pension schemes: if you make opting in the default position rather than an active choice, people sign up in greater numbers. They are free to opt out, which is a crucial feature of nudges â they must be âfreedom preservingâ. The goal of the Nudge Unit, then, was to see whether this approach could improve the design and implementation of public policy.
âI think weâve gone from âthis is an interesting idea that probably wonât workâ to âactually we know itâs highly effective in a whole range of domainsâ,â David Halpern, the head of the unit â officially called the and now an independent company â told me before the pandemic. So what started as an exercise in nudging people to make better life choices has expanded into a global enterprise in behavioural engineering.
âItâs really important at most steps of the way: you have to communicate with the general public, you have to think about how you do it consistently and clearly and in a way that people will understand and take the actions,â says Ulrike Hahn, a psychologist at Birkbeck, University of London. âYou have to think about social mechanisms for getting people to do stuff.â
The BIT is active in 30 countries and just opened branches in Canada and India. Last yearâs in London attracted more than 1000 delegates from all over the world and every conceivable sector of society, including public health.

Mixed messages
As soon as it became clear that the new coronavirus was poised to become a pandemic, behavioural scientists around the globe joined their biomedical colleagues in dropping whatever they were working on to find ways to tackle the virus.
One of the first groups out of the blocks was the BIT. It used its preferred tool â a randomised controlled trial â to test the effectiveness of handwashing information posters. It recruited 2600 adults in the UK and ran an online trial of various posters from around the world (translated into English). Participants were tested on their recall of the message and whether they said they intended to wash their hands more often after seeing them. The results showed that had a âbright, clear design with minimal text and an emphasis on the step-by-step procedureâ.
You might ask why a randomised controlled trial is necessary to reach this conclusion, but behavioural science doesnât always produce obvious answers.
Crockett and her team, for example, on peopleâs intentions to wash their hands, avoid social gatherings, self-isolate and share health messages. They expected practical, utilitarian messages to be the most effective, but found that they barely worked at all. Morally charged ones, especially those emphasising our responsibilities towards family, friends and even strangers, were much more effective.
Another team that was quick off the mark was the . In March, as the number of covid-19 cases in Italy span out of control, it identified more than 100 research papers and wrote a , âUsing behavioural science to help fight the coronavirusâ.
âThere is a body of applied scientific knowledge that can be called upon,â says team leader . âWe do know that multiple measures can be taken that are likely to reduce transmission.â Some of these focus on individual behaviour, such as washing our hands or touching our faces, while others encourage actions that benefit society at large.
The team found seven areas where behavioural science can contribute: hand cleanliness, face-touching, coping with isolation, encouraging collective action, avoiding antisocial behaviour, crisis communication and risk perception.
The review was published on 12 March and formed a key strand of the Irish governmentâs strategy. âWe sent them a copy of the paper on the morning we released it, and theyâve been using it ever since,â says Lunn. âItâs been used to guide quite a lot of the Department of Healthâs messaging, some of the stuff in the papers, the stuff in the telly adverts here.â
Certain interventions are simple and obvious, says Lunn. âHandwashing and hand-sanitising is pretty straightforward. You put the sanitiser in a place where people cannot miss it. If you walk around it, you might suffer some social disapproval because weâll see youâre not using the sanitiser. It works: most people use it more. Itâs a nudge, basically.â
Others are more complex and trickier to pull off. Encouraging collective action, for example, is a classic public goods problem where enough people must override their own self-interest in pursuit of a common goal. Existing research suggests that : willing to make sacrifices for the greater good, but only if others do too.
Strike a nerve
The trick here, says Lunn, is to generate a common group identity. That means âgetting across that we are in it together and communicating to everybody a strategy that says, âIf we all do X, we will all be better off, and hereâs whyâ. And also introducing gradual degrees of social punishment and disapproval for people who donât bat for the team.â Think tutting when people donât social distance or challenging those who break the rules.
Emotions also sway our decisions and behaviours around the virus. In a more recent experiment, Lunnâs team showed people posters including one that emphasised the possibility of infecting a specific at-risk person, such as someoneâs grandmother, or a neutral poster communicating the governmentâs advice.
When asked later about their plans for the coming days, those who had seen the emotion-fuelled posters , even though participants themselves predicted that the neutral posters would be more effective.
The Irish government enacted a progressive tightening of social freedoms, culminating in a lockdown on 28 March. According to Lunn, this was greeted with a high level of compliance and trust. âPeople are responding,â he says. âI think the general view here at the moment is the chief medical officer has played a blinder.â The policies also appear, tentatively, to be working. If Irelandâs experience shows how behavioural science can help, events across the Irish Sea show how it can also go wrong.
Compared with its European neighbours, the UK took a relaxed approach to behavioural restrictions. The handshake-happy Johnson of 3 March was merely following official advice that handwashing, not social distancing, was the key to halting transmission. But this laissez-faire approach didnât work, and on 23 March, the government imposed a lockdown.
Precisely what guidance inspired the original policy and its sudden reversal is unclear, not least because the government has been decidedly secretive about the advice it has been receiving. But we know that it has heard from a team called the Scientific Pandemic Influenza group on Behaviour and Communications, originally convened in 2009 in response to the swine flu epidemic and reactivated on 13 February 2020 to respond to the new coronavirus. The groupâs remit isnât to propose policies, but to advise on how to implement those recommended by medical experts.

The consensus among behavioural scientists is that they made some bad calls. âIn all honesty, I think they just got it wrong,â says Lunn. âAnd I think they know they got it wrong now. And I think thatâs what the large majority of the behavioural science community, in Britain and internationally, think.â
On 16 March â a week before lockdown â the government open letter signed by nearly 700 UK-based behavioural scientists expressing deep concern about its social distancing policies.
âAlmost 700 behavioural scientists wrote a letter of deep concern about the UKâs social distancing policiesâ
One of the letterâs lead authors was Hahn. She says the main problem was that the government put too much emphasis on âbehavioural fatigueâ, the worry that people would rapidly tire of measures limiting social contact and abandon them just when they were most needed. âWe always thought that that argument was overstated,â she says. âThe evidence for it is not very strong.â
To make matters worse, the UK government didnât initially share the evidence base for its strategy. When it eventually did , behavioural scientists were unimpressed. âThat document didnât really elaborate on this behavioural fatigue thing,â says Hahn. âI havenât changed my mind.â
It isnât that behavioural fatigue doesnât exist, she says â as many can attest after weeks or months of lockdown. âIt is not implausible: keeping up behaviours â in particular ones where you donât see an immediate return, but that are onerous â is going to flag over time. So I donât think itâs a non-issue. What was troubling me was the extent to which it was being used to justify whether or not to move ahead with a more extreme lockdown.â
Lunn is less forgiving. âThe evidence is pretty weak,â he says. âAnd why it came out after the fact, I donât know.â
âA gradual lifting of lockdown is better â the stronger the shock, the more people struggleâ
The advice also appears to have put too much emphasis on a narrow, nudge-based approach to behavioural change while ignoring the perspectives of other behavioural sciences such as psychology and behavioural economics, says Hahn. Many people detect the fingerprints of the Behavioural Insights Team on the strategy, although it hasnât commented and declined a request for an on-the-record interview.
Another concern is that the UK response was politically motivated. In essence, the fear is that the government cherry-picked advice that fit its libertarian instincts â or, as Johnson put it when announcing the lockdown on 20 March, âthe ancient, inalienable right of free-born people of the United Kingdom to go to the pubâ.
This is all in stark contrast to the behavioural expertise that was brought to bear on the UKâs swine flu preparations a decade ago, says Hahn. âThere was a very thorough discussion of the behavioural science evidence underpinning those strategies,â she says. That included research that is still relevant today, including on face mask compliance and maintenance of social distancing.
The UKâs failures, however, donât negate the fact that behavioural science can help with the crisis. âIt still has a lot to offer,â says Hahn.

Right now, the most pressing question is how to maintain, and eventually lift, lockdown. Behavioural science can offer personal advice for how to play the long game, says Lunn (see âThe behavioural science guide to getting through lockdownâ). But there are also some insights for government.
âOne of the reasons I think the Irish authorities did better that the UK authorities was by being more gradual,â he says. âThe UK essentially went in two jumps, doing very little and then slamming very strong restrictions on extremely rapidly. We imposed restrictions earlier, then increased the level in four stages.â
The gradual approach is better, he says, because the stronger the shock, the more people struggle with the new situation. âSocial support takes time to organise itself, and if you do things really suddenly, some people canât cope.â
The same logic should work for ending lockdown. âIt will be much better to do it in more gradual stages, where specific restrictions are lifted one at a time. And I get the logic that weâll need to ease restrictions and then possibly put them back down again, depending what the data show. Communicating that is going to be super important,â says Lunn.
The best way to do that is yet to be determined, as this is such a novel problem. Yet crisis communication principles used by the US Centers for Disease Control and Prevention, which rely heavily on behavioural science, offer some insights.
These include being open about information, including what you do and donât know, telling the truth, expressing empathy, giving people something to act on and showing respect. In terms of nudging, openness shouldnât be a problem, because â surprisingly â it still works even when we know we are being manipulated.
The behavioural science guide to getting through lockdown
Lockdown isnât easy to deal with. âI feel completely disoriented. My worldâs been turned upside down,â says Pete Lunn, head of Irelandâs Behavioural Research Unit and lead author of the paper But, he says, there are things you can do to help get through it.
1. Habits
âOne of the really interesting things at a time like this is that people break habits and do different things. This is an opportunity to try something new, and form good new habits. Try that thing that you never did because you just carried on with your perpetual behaviour.â
2. Connectedness
âEverybody is suffering at the moment. Weâve been sampling peopleâs well-being throughout the day and itâs as if the entire population has been made unemployed all at once. One of the reasons is that people are feeling isolated. Theyâre feeling lonely, theyâre feeling like their social contacts are not exciting. So get in touch with old friends, make sure that youâre contacting parents and family on a regular basis. This is really important.â
3. Outdoors activity
âWe can see in our data that the thing that gives people the highest sense of well-being is anything where theyâre outside. Wherever people are outside, theyâre happier. So find safe ways to get yourself out. That exercise once a day is vital, because it feels normal again.â
Think first, share later
Like many biomedical scientists, behavioural scientists are scrambling to create rapid interventions designed to slow the pandemicâs spread.
Gordon Pennycook at the University of Regina in Canada and his team wanted to understand why some people believe misinformation about the virus and share it on social media. Their goal was to design an intervention to stop them.
It turns out that most people who spread falsehoods donât do so maliciously. Instead, the researchers discovered that people are far worse at determining whether something is true or not when deciding whether to share it on social media compared with when they are asked directly about the accuracy of the information they are sharing. A simple prompt to think about the accuracy of a non-political headline
Social media platforms should add an âaccuracy nudgeâ to reduce the circulation of dangerous misinformation, says Pennycook.