Social Norms: An Underestimated Tool to Change Behaviour

Why are social norms effective?

Social norms have the powerful potential to change people’s behaviour. We follow what others do. So, finding out how others behave or think, when we don’t know or have biased beliefs, often causes us to change our own behaviour or opinions in order to adhere to the social norm. This is especially true when others refers to those that are like us.

How are companies changing behaviour using social norms?

Opower, an energy company, tells consumers their usage relative to their neighbours (remember, others should be similar to us). Above average consumers reduce usage to be like everyone else. Average consumers stay pretty constant initially. As those over-consuming “correct” their behaviour with each report, the average lowers and the previously average consumers follow. Below average consumers receive positive feedback to lessen the chances of feeling exploited by free-riding neighbours and keep their consumption consistent. Monthly reports are more effective than quarterly reports and treatment effects have been shown to persist after one year, as habits are formed.


Since social norms interventions can target a large treatment group with meaningful long-lasting impacts, they can be an incredibly cost-effective way of steering people towards desirable behaviours both in the private and public sectors.

But social norms aren’t always the answer…

Say you want people to increase their pension pot contributions. It wouldn’t be wise to inform those who contribute above average that the majority of people actually put less into their pension. This subgroup would be unlikely to increase their contribution and might actually decrease it to be in line with the norm. This counter-reaction — the boomerang effect — illustrates the importance of carrying out a pre-mortem from the perspective of different groups to identify potential unintended consequences. Thinking what could go wrong helps to adjust and strengthen the intervention. In this case, norms could be tailored to subgroups (e.g. complementing the distributional information with positive reinforcement for above average contributors) or an alternative tool might be considered.

Prescriptive vs. Descriptive Norms

So you’ve decided a social norm intervention will be effective in driving a certain behaviour but what type of norm is best? Prescriptive (or injunctive) norms prescribe how people should behave whereas descriptive norms describe how people actually behave.

Descriptive norms are effective when the desired behaviour is the norm but individuals are unaware of this. Say a supermarket wants customers to eat more sustainably and the research finds that customers tend to overestimate the amount of meat fellow customers purchase. By correcting this misperception, individuals are likely to follow suit and also purchase less meat.

Whereas prescriptive norms are useful when the desired behaviour isn’t the norm but people think it should be. For example, men in Saudi Arabia think women should be able to work but the norm is that they don’t. By exposing this commonly held but rarely shared opinion, men are more likely to publicly support women working.

Tips to design a successful social norm intervention

1. Make it truthful

Share social norms that are obtained from real data. Not only is it unethical to pick a statistic out of thin air but if people catch on that the message isn’t credible then it’s likely to backfire.

2. Make it regular

Collect and communicate social norms routinely over a period of time. While one-off interventions might yield effects they will quickly decay. Current and consistent information is key.

3. Make it actionable

Link the social norm to a clear actionable change. Say you want commuters to avoid public transport then inform them that 7 out of 10 people in their borough do this (if that’s true) and include directions to the nearest Santander Cycles docking station with bicycles available.

4. Make it personal

Consider the characteristics of the individuals that you are targeting. Are there any sub-groups that could bias the treatment effect? If there are then personalise the intervention at the group level to successfully target different types of individuals.

Thoughts by Catherine Bouckley

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Ayres, I., Raseman, S., & Shih, A. (2013). Evidence from Two Large Field Experiments that Peer Comparison Feedback Can Reduce Residential Energy Usage. Journal of Law, Economics, and Organization 29 (5): 992–1022.

Yamin, P., Fei, M., Lahlou, S., & Levy, S. (2019). Using Social Norms to Change Behavior and Increase Sustainability in the Real World: a Systematic Review of the Literature. Sustainability. 2019; 11(20):5847.

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