In Australia’s Covid-19 response, the importance of expertise in medicine, biology and epidemiology has been on display. The pandemic appears to be heralding a pivot back to evidence-based ‘fact’, away from opinion and ‘truthiness’. Universities and medical research institutes are at the forefront of research to understand the biology of the virus, trial a vaccine, test potential treatments and model the spread of infections.

It has also become clear that behavioural change by every individual is necessary to reduce the spread of infection. Compliance with social distancing measures by 90% of people means the virus can be controlled in the community; compliance by 70% means it won’t be. Social and behavioural science is critical in this effort and needs to be better mobilised to support behavioural changes.

Some recent articles ^[1] highlight insights from social and behavioural science that relate to threat, panic, culture, leadership and political polarisation.

A central idea is that reducing the spread of Covid-19 through behavioural change is a problem of the collective, which puts it in the realm of group psychology.

In social and behavioural science, there’s consensus ^[2] that there are three main ways to change behaviour:

• coercion—people receive rewards or punishments on dimensions that are valued by a community
• authority—people follow the leader (or laws, customs, policies or norms) even when they don’t fully agree, because they accept the process that invests certain powers in a particular individual or body
• persuasion—there’s a shared goal and the behaviour is believed to be right, valid and appropriate.

Often a combination of all three is in operation when efforts to change behaviour are driven by public policy. Persuasion is the ‘sweet spot’ because there’s shared purpose, which brings intrinsic motivation and self-reinforcing behaviour. Coercion is costly because it requires surveillance and enforcement.

The critical questions then are how do we foster persuasion and how can social and behavioural science be of use? How do we persuade people to engage in social distancing, hygienic practices (including washing hands and surfaces) and self-isolation, and to continue doing those things for many months?

Humans have an inbuilt (perhaps evolved) functionality that enables persuasion. It’s on display every time we support a sports team. It affects the way we perceive the world (who’s right or wrong), who we listen to, who we follow and who we help.

Humans can expand their self-concept to include others who are similar to themselves, or ingroup members. This is referred to as a social identity (in which the self is defined as ‘we’ and ‘us’), and contrasts with a personal identity (in which the self is defined as ‘I’ and ‘me’).

Importantly, the ingroup that’s most relevant to our behaviour can change (such as from home to work, on the sporting field or at the ballot box). The self-concept can include a few others like friends and family, a local community, an organisation, a nation or even humanity as a whole. Research has demonstrated that when there’s a shared social identity there is an increase in cooperation, following of group norms, helping, empathy, trust and, importantly, persuasion.

During this pandemic, persuasion and behaviour change will flow from the emergence of a shared social identity with a clear understanding of common (community or nation, not individual) fate. Because it’s a group, or herd, problem, it needs to be addressed at the group level. Political and policy leaders are central to the creation of a shared social identity and associated norms that are tied to a common purpose and underpinned by values like caring for others, supporting those in need and being responsible citizens.

Some leaders are crafting this sense of who ‘we’ are and what ‘we’ need to do better than others, and their efforts will need to be strengthened and maintained over the next several months. To act together, we need consistent and clear behavioural expectations, guides on how to act (such as spacing markers on shop floors for queueing) and the establishment and showcasing of those new norms. Influence is reduced where leaders behave badly, there’s political polarisation or messaging is inconsistent.

Importantly, successes need to be reinforced—when the right behaviour is on display it needs to be championed. Leaders should consider regular and widespread electronic messaging not just communicating what people should do but that people like them (in the same group) are doing the recommended behaviours.

People need to hear and see that others in the group are changing their behaviour and that the right behaviours are on the increase. On this front, every piece of news about fines being issued for noncompliance should be met with circulation of many examples of the right behaviour.

We also need reassurance that there is hope if we act as a collective. It has to be clear that acting together now, and for many weeks to come, means the end will be in sight sooner. There needs to be personal and collective efficacy—a sense that one’s own and one’s group’s actions will lead to positive change. In the past week or two, many of these strategies have been on show, but is the message getting through en masse? Can persuasion be maintained? Are there pockets of ignorance or even resistance? All members of the community need to be engaged in the solution or we will fail.

Nationally representative weekly surveys to assess Covid-19-related attitudes, compliance behaviour, mental health and wellbeing, coping and resilience will be informative in designing strategies to support behaviour change during this crisis. They’ll also help in identifying needs in the recovery phase. Who is coping and who isn’t? What predicts behaviour change? What’s the mental health impact and what supporting measures are needed? Are more cohesive local communities managing better? Are feelings of loneliness on the increase and what can be done? The foresight that comes from high-quality information will enhance both the management of and recovery from this pandemic.