Agent-based simulation of an environmental action campaign: Changing people's behaviour via their inner contradictions

Everyone has inner contradictions, and particularly in the area of the environment, many people act in ways that contradict their intentions. Measures that make people aware of these discrepancies trigger inner processes that can lead to changes in behaviour. In an action campaign promoting voluntary slower driving speeds in a Swiss municipality, our use of measures that confronted people with contradictions resulted in a remarkable reduction of average driving speeds. The processes triggered in persons during the campaign were simulated by means of an agent-based simulation. To this end, we developed a model based on the social psychological theory of cognitive dissonance. This theory states ways in which people deal with inner inconsistency. The simulation model was fed with data that was collected in a representative survey both prior to the action campaign (pre-survey) and after the campaign (post-survey). The data from the presurvey served as the initial data for the simulation; the post-survey data allowed us to determine people's perceptions of the measures as well as attitude and behaviour changes. Assumptions were formulated as to how the measures work. Using these assumptions and the collected data, it was possible to model successfully the dissonance processes occurring in people through the course of the action campaign: For more than 60% of the simulated persons, their attitudes and behaviour changes were (post) predicted correctly with a deviation of 20 points. For future action campaigns, therefore, it should be possible to determine in advance the measures that will be most effective by conducting simulations on the basis of preliminary surveys.