2. Use social norms

Purpose: To encourage sustainable behaviour by informing people about the action of others

Why and how it works

The effect that social and cultural norms have on people’s behaviour is well studied and documented. Going back in time, being able to cooperate and adapt to our group of hunters and gatherers was key to survival. Also in today’s individualized society being socially excluded cause a real threat to human health. Clearly, behaving different to others around us can result in such exclusion. One barrier when promot- ing sustainability is that we tend to under- estimate the extent to which other people recycle, save energy and so on. In such a situation it can have a big effect merely to inform people that many people actually carry out the desired behaviour. As shown by the example to the right, we are more influenced by people that we identify with and feel more similar to.


The impacts of social norms don’t only work to encourage sustainable behaviour. If most people in a group we want to influence carry out an undesirable behaviour, informing them about the problem can reinforce and strengthen that very same behaviour. An American study has shown that giving households information about the energy consumption of their neighbours can lead those with a lower than average consumption to actually increase their consumption as a result (more information about this study is found on under strategy 5).

Recommendations for implementation

This strategy can be used to strengthen sustainable behaviour in situations where most people already practice and/or agree with a desirable behaviour. Social norm campaigns have been used successfully to motivate people to recycle and to encour- age lower energy consumption. It can be a particularly successful when working with smaller groups in which people feel a strong connection to one another. Being aware of the impact of social norms is also important in order to avoid strengthening unwanted behaviour in society. As always, testing and evaluation is the key to make sure it works in practice.

Example: Using social norms to motivate environmental conservation in hotels


It has because common practice among hotels across the world to encourage their guests to reuse their towels during their stay. Robert Cialdini, a famous American professor of psychology and his research colleagues came across evidence that 75 per cent of the guests staying at hotels with signs about towel-reuse in the US actually reused their towel at least once during their stay. Accordingly they wanted to test whether informing people about this could increase the motivation for more people to participate.


Cialdini and his team selected a midsized and midpriced hotel in the Southwest that was part of a large hotel chain, to conduct two experiments. In the first experiment they compared the use of two different signs. The first sign used a standard message focusing on the importance of environment protection. The second informed the customers that the majority of guests actually reused their towels at some part of their stay. The experiment was carried out during a period of 80 days and collected data from 1 058 instances of potential towel reuses in 190 rooms. In the second experiment the research team added three signs to test the importance of group identification. One focused on guest staying at the same room, another used the word citizens instead of hotel guest and the third emphasized the gender identity. This experiment was carried out during 53 days, gathering data from 1595 instances of potential towel reuse. The hotel’s room attendants were carefully informed and trained about how to collect data during both experiments. 


The first experiment showed that informing people about the common practice of others yielded a significantly higher towel reuse rate. Whereas only 35 per cent of the guests exposed to the information sign reused their towel, 44 per cent exposed to the social norm message did the same. The second experiment showed that informing people about the behaviour of previous guests staying in the same hotel room raised the number of people who reused their towel to 49 per cent. The other norm-related messages all raised towel reuse to the same extent as informing about the behaviour of hotel guests in general.

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