Cooperation in social dilemmas: How can psychology help to meet climate change goals?

Effectively managing shared natural resources is essential to protecting and improving our physical environment. This cannot be done without cooperation at international, national and local levels. Bringing together research on social dilemmas from the laboratory and the field gives us hope that we can work together to make a difference: we are social beings not ruled purely by economic motives, but influenced by our social context. Two significant insights from psychology that can help us to fight climate change are the roles of social norms and shared identities. We draw attention to environmentally friendly behaviour as the norm for people we identify with, and promote shared identities at local, national, and global levels in different contexts. While these processes could work for and against the climate change cause – e.g., local needs can conflict with global ones - we make recommendations for policymakers to harness their effects in specific ways.

Introduction: The Climate as a Global Commons

One hundred and ninety-five countries have now signed the recent Paris Agreement (European Commission, 2015) on climate change. The goal is to keep global warming well below 2oC. Many are pessimistic about our ability to meet this ambitious goal. The challenge of the environment has been described as a “global commons problem” requiring “international cooperation” (IPCC, 2014). 

Effective collective management of our planet’s common natural resources - such as oceans, air, forests, and fossil fuels - can improve the environment and reduce global warming. But are we able to overcome our short-term, individual interests to plan long-term and work together to manage these resources effectively? We focus on two processes from research on social dilemmas involving shared resources that can, in the right circumstances, be applied by policymakers to increase cooperation, benefiting collective interests rather than individual ones: social norms and shared identities.

Social Dilemmas

We bring experimental research on social dilemmas together with field research on real-life environmental dilemmas. Two social dilemmas, the commons dilemma and the public goods dilemma, are useful in conceptualising real environmental challenges. For example, clean air has been described as a public good (e.g. Parks, Joireman, & Van Lange, 2013) because people contribute to it by, for example, using fewer pollutants or building more forests. But it has also been described as a common resource from which we take (e.g. Hardin, 1968; Van Lange, Joireman, Parks, & Van Dijk, 2013) because we reduce the totality of clean air by polluting it. So research on both social dilemmas will be useful for understanding the problem and for identifying ways to encourage pro-environmental behaviour.

We are not 100% rational

It used to be thought that behaviour in social dilemmas followed purely rational processes (such as calculating personal risk, gains and losses, and acting accordingly). Later it became clear that the social context makes us subject to a number of influences and biases which a rational model of human decision-making cannot account for (see, for example, Kahneman, 2011): we often cooperate more in social dilemmas than economic models assuming pure self-interest would predict (see e.g. Weber, Kopelman, & Messick, 2004). These influences include our perceived norms about environmental behaviour and the groups we belong to.

Social norms

We are influenced by what we perceive as normal behaviour

It is important to distinguish between two types of social norms for environmental behaviour (Reynolds et al., 2015).  Descriptive norms tell us what people do, such as “most people recycle”, and “my neighbours don’t use too much electricity”. Injunctive (or prescriptive) norms tell us what we ought to do, such as “it’s not acceptable to take too many flights”.  Norms can have a powerful influence: when recycling behaviour became widespread in the UK, this was then seen as something everyone does, which created a new norm (Rettie, Burchell, & Riley, 2012). This norm, in turn, makes us recycle more (Barr, 2007), setting up a virtuous circle.

Use defaults to convey norms

When unselfish behaviour is the “default” option, people are more likely to behave unselfishly. This is because defaults convey what most people do (Everett, Caviola, Kahane, Savulescu, & Faber, 2015), such as most people recycling and being careful with their energy usage. We have seen the recent effect of making people ask and pay for plastic bags in shops: now that you are not offered a bag automatically, the default is to bring your own bag. The effect in Wales over three years has resulted in a 79% drop in plastic bag consumption, which will have positive effects on the environment (Defra, 2016). Defaults could be applied to carbon off-setting: there could be an automatic contribution for each flight booked, unless one opts out. For example, Heathrow to Granada would cost £14, according to an online calculator (

Communicate localized norms

A simple message in hotel rooms saying “the majority of guests reuse their towels”, which invokes a norm, is more effective than messages that simply encourage or provide the opportunity to reuse towels (Goldstein, Cialdini, & Griskevicius, 2008). Even more effective is “the majority of guests in this room reuse their towels”, because we identify with those guests based on a very specific locality. Other environmental behaviours of guests could be encouraged in the same way, such as water and electricity usage. We could also be provided with usage data about previous occupants of our homes.

Convey what environmentally friendly behaviour happens and what ought to happen

Another study showed that when households are informed of the average amount of energy their neighbours use, they tend to adjust their own use to that norm (Schultz, Nolan, Cialdini, Goldstein, & Griskevicius, 2007). This did in some cases work against the environment, when people with low usage adjusted up to that average. However, by adding a message of approval (simply by using a smiley happy face emoticon next to the amount reported) when usage was below average or disapproval (an unhappy face emoticon) when above average, this unwanted adjustment was eliminated. This shows that a norm needs to be communicated in a way that is not just descriptive but also injunctive, conveying what is considered to be right and wrong. Of course it will not help to publicise the environmental behaviour of the average member of the public when it is detrimental to the environment. But when supporting data exists, policymakers should take advantage of it, making clear their approval or disapproval of a particular behaviour as well as communicating what the norm is. 

Emphasise ethical rather than economic considerations

Pillutla & Chen (1999) show that people behave less selfishly when a laboratory social dilemma is introduced as a non-economic activity (contributing to a social event rather than investing in a joint investment fund). The economic context is thought to activate an implicit norm that behaving competitively is appropriate in such a setting, whereas the non-economic context generates cooperative norms. In other words, the social context can prime particular ways of behaving. Norms about how to behave in social dilemmas can also be conveyed implicitly through the use of sanctions. In a laboratory social dilemma about pollution, sanctions caused the dilemma to be seen as a business decision rather than a decision that was about ethics, which again reduced cooperation (Tenbrunsel & Messick, 1999). Policymakers should therefore emphasise ethical considerations more than the economic advantages of environmentally friendly behaviour, to prevent us from entering into a competitive frame of mind when making environmental decisions.

We should not invent norms for the sake of the environment

Data about average usage might not support climate change goals. In such a case, we by no means want to imply that changing the actual figures to create a social norm that induces better behaviour would be justified. That would be in line with neither a deontological nor a consequentialist approach to ethics. On the former we should not lie, and on the latter we should not create the risk of severely reducing trust in the authorities and the norms they communicate, as this would be counterproductive.

The Groups We Identify With

Emphasise the groups we belong to

Social identity theory (Tajfel & Turner, 1979) proposes that we don’t identify and act just as individuals, but as members of social groups (ingroups) - such as our local community. We act to benefit our ingroups and aim to be perceived positively by them (cf. Faber, Savulescu, & Van Lange, 2016). Emphasising a shared group identity among participants can increase cooperation in laboratory social dilemmas (Brewer & Kramer, 1986). This shared identity is conveyed through the participants sharing a “common fate”: how much the participants take away from the shared resource (usually money in an experiment) depends on what others do, so that all are dependent on each other. Obradovich and Guenther (2016) found that emphasising collective rather than individual responsibility increased donations to climate change efforts by 50% in the general public. This emphasis on collective behaviour could be present in all communications about the environment to the public.

We have competing identities

We may belong to many groups, from the local to the global: a family, a town, a nation, and the planet. But these groups can have conflicting goals or values: for example, your need to provide for your family may deplete a shared local resource, negatively affecting the community. Our local identity (identifying with a local community) is subordinate to our superordinate global identity (identifying with all who live on the planet). The multi-layered needs of the group social dilemma (individual, local, national, global) create a complex path for the policymaker to tread. However, below we show that we can sustain multiple levels of identity with positive consequences for cooperation (Dovidio et al., 2012).

Local identities motivate us

Van Vugt (2001) found that people who highly identified with their community did not need an incentive to persuade them to consume less water. Other studies show we believe that members of our ingroup share values such as fairness with us (Hogg & Reid, 2006), which then makes us act more fairly (De Kwaadsteniet & Van Dijk, 2012). So local government and businesses should strengthen community identity as part of their communication with the public and by supporting community events and projects.

Emphasise that we have a global, superordinate identity

However, an emphasis on local group membership, while having benefits described above, focuses attention on differences between groups, which may also have costs. We may be more trusting and cooperative in laboratory social dilemmas towards ingroups than outgroups (Brewer, 2008). A superordinate, global identity, as citizens of the planet – as far as this can be achieved – may also be needed to motivate people to include future generations (Van Vugt, 2009) and other countries in their group identity. A superordinate identity reduces bias, and increases helpfulness, towards members of the subordinate groups included in the superordinate category (Dovidio et al., 1997; Levine, Prosser, Evans, & Reicher, 2005).

There are several studies that show the positive effects of a superordinate, global identity on the environment. Kramer and Brewer (1984) found a superordinate identity increased cooperation when a laboratory common resource was being depleted, and Buchan et al. (2011) found that those with a strong global identity contributed more to a global laboratory public good, where participants were told their decisions affected people from other parts of the world. Those feeling a sense of global interconnectedness had more empathy for other groups, valued environmental sustainability, and felt responsible for making the world a better place (Reysen & Katzarska-Miller, 2013). Public documents about the environment should emphasise our interconnectedness, through images as well as words (Corner et al., 2015).

Identifying with the whole planet can be challenging. Brewer and Kramer (1986) found that group size had no effect on cooperation, but Kerr (1989) found that larger groups reduce perceived self-efficacy. However, increasing our sense of connectedness - as recommended above - increases self-efficacy, which in turn improves socially responsible behaviour (Cojuharenco, 2016). Local government should communicate the extent to which local actions contribute to the global resource, in order to increase self-efficacy.

Resolve conflicting local and global needs

An example of a conflict between local and global identities is the phenomenon of NIMBYism (“Not In My Back Yard”), as when windfarms are opposed by local communities that are supportive of environmental interventions in principle. This has been explained as a threat to place identity which can be reduced through better communication by developers: they should focus instead on social identity and aim to reduce the perception that the group is threatened by changes to the physical environment (Devine-Wright, 2009). Emphasising the good that windfarms achieve could instead boost group self-esteem.

Encourage friendly competition between local groups

Bias between local groups is reduced by simultaneously holding subordinate and superordinate identities (Hornsey & Hogg, 2000), but differences should still exist (Hewstone & Brown, 1986). Parks et al. (2013) and Van Vugt (2009) argue that friendly intergroup competition can be used for good, such as a competition for a clean city award. Ingroup love does not necessarily mean outgroup hate (Brewer, 1999): competition does not have to be hostile, especially when there are shared goals. These efforts could be sponsored by local businesses. Policymakers should encourage a sense of pride in the local community, and provide detailed public feedback to communities on their progress towards efficient shared resource management, such as their collective use of water, local transport and recycling facilities, compared with other local communities. What would be your response to finding out that nationally 87% of paper packaging is recycled, but in your neighbourhood it is only 60%? Hopefully you would be motivated by your community identity - and a light-hearted sense of competition - to improve it.

Ethical Considerations

As we have shown, psychological processes can be harnessed to influence behaviour. However, importantly, "can" does not imply "should". Our choice to influence people's behaviour ought to be ethical. There is always the potential for misuse of psychological knowledge, as history shows.

When is using psychological research to influence behaviour ethical? Firstly, when the goal is ethical – that is, of genuine value. Minimising climate change is agreed to as a reasonable goal by the vast majority of scientists (Doran and Zimmerman (2009) estimate 97% consensus). Secondly, the costs of achieving that goal must be reasonable (Savulescu & Hope, 2010). Estimates of costs and benefits, and their probabilities, should be based on a systematic review of the evidence, with further research (including modelling) when the evidence base is insufficient relative to the gravity of the expected benefits and harms. The most minimal interpretation of "reasonable" is when the costs of intervening are minimal. (A higher standard would be that costs are proportionate to benefits and have been minimised.) Costs include restriction of freedom, undermining of autonomy, lowering of well-being, and increasing inequality or injustice. A policy involving reasonable costs might be default carbon off-setting for flights. Thirdly, there must be public transparency about means and ends, such as open access to data used for norms as discussed above. Fourthly, there must be ongoing monitoring of the effects, as well as capacity for revision through some kind of democratic participatory procedure, which could reduce NIMBYism towards windfarms. Regular feedback to the public on the effects of new regulations such as recycling and plastic bag charges are also good examples. All these requirements can – and should – be met when using psychology to change people’s behaviour in the context of climate change.


The evidence from social dilemmas suggests there are circumstances in which we as social beings will behave unselfishly. There is much that can be done to address the problem of climate change. Policymakers and businesses could capitalise on the effects of positive norms, and note that we respond to a sense of belonging to groups at different levels. Psychological processes – when they are accompanied by structural solutions and are implemented ethically – have the potential to help prevent what may soon become irreversible detrimental effects on our planet and its resources.


This research was funded by a grant by the Oxford Martin School [Oxford Martin Programme on Resource Stewardship], supporting N. S. F. and J. S.


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