Why and how it works
All conscious behavioural change starts with a commitment of some kind. There is a lot of research that shows that people are more likely to actually complete a change in their lives if this commitment is made formally and/or in public. The reason is strongly related to the power of social norms. Breaking a commitment could cause a bad reputation or in other ways have a negative impact on our image. Also on an individual level setting up goals for one self can be an efficient way of motivation as it makes us feel good about ourselves when we achieve a new goal. The Durham Water example from Canada is an example of how getting people to sign a pledge can boost behavioural change.
The main limitation with this strategy is to get people to make a promise or sign a pledge in the first place. Achieving this clearly needs a combination of other strategies such as attracting interest or using some sort of incentive, making it hard to evaluate the effect of the actual pledge. In the Durham Water example using a door to door method with educated employees for instance may have been more important than the actual pledge that was used.
Recommendations for implementation
Public commitments and pledges can be used as an add-on strategy to activities that target a specific behaviour change. With modern day technology such as Facebook it is also a lot easier to get people to commit to specific campaigns and thereby indirectly influencing many more. In 2011 The Swedish Society for Nature Conservation developed a campaign called Anti Scampi targeting individuals, grocery stores and sushi restaurants in order to get them to commit to stop eating, selling and serving giant prawns. The campaign turned out to be a great success resulting in all main Swedish grocery stores removing giant prawns from the shelves.
Example: Using a pledge to reduce water consumption of house holds
In 1995 the Regional Municipality of Durham in Canada realised that the growing population and people’s water habits was a threat to the water supply. In particular it was becoming a problem on dry summer days, mainly because people were watering their lawns. Since no technological fix was available to increase supply they realised that the only way forward was to try to convince the residents to reduce their water consumption by getting people to water their lawns less.
In 1997 Durham committed a trial with 200 households in the town of Ajax which aimed to compare different methods of targeting people. The trial showed that the most efficient way of reaching people was to use trained employed students with good communication skills to make home visits. In 1998 the programme was expanded to target 900 households in six communities using six trained student employees. This time the students were asked not only to give information and advice but to convince the homeowners to sign a written commitment form to water their lawn a maximum of one inch per week. During the years to come the programme has been further developed trying more tools and covering even more households. Using the commitment form has been used repeatedly as part of the strategy.
The result of the first trial in 1997 showed that using trained student employees who made repeated home visits to people reduced lawn watering by 26 per cent compared with the control group. During the 1998 when the pledge was used, students managed to get 88 per cent of the households to sign the pledge and managed to replicate the 26 per cent reduction in water use, despite covering a larger area. In 2 000, students managed to reduce water use with 32 per cent developing their strategies even further, for instance by avoiding a coercive and lecturing approach when getting people to sign the pledge.