Nudging travellers to societally favourable routes: The impact of visual communication and emotional responses on decision making

As urbanisation increases, in many places, the transport system is suffering from problems that may affect large parts of the urban population, such as traffic congestion or increased air pollution. In both cases, a better distribution of traffic flows could contribute to establishing a more sustainable transport system, and to improve the situation from a societal point of view. In this paper, we use cartographic symbolisation for communicating favourability of route options for achieving a societal benefit. Since map symbols can evoke different emotional responses in the viewer, we investigate to which extent map symbols evoke positive and negative emotions and whether these influence route choice decision making. We created different cartographic visualisations and designed a user study that investigates the effectiveness and suitability of these different visualisation variants for influencing route choice based on two scenarios: traffic and air quality. Fourteen route maps were prepared using different map symbols to symbolise societally favourable and non-favourable route options. The results of this study show that map symbols can be used effectively for influencing route choice towards choosing the favourable route for the two tested scenarios. While visualisations that modify only lines were more effective in the traffic scenario, area symbol modifications were more effective for the air quality scenario. The symbolisation evoked a wide range of emotions in participants. While non-favourable routes mainly evoke negative emotions (particularly fear), favourable routes mainly evoked positive emotions (particularly contentment) or no emotions. The results further demonstrate that for some of the visualisation variants, emotions felt in response to the map visualisations contributed significantly to changing the route choice decisions in favour of the societally favourable route option. The findings of this research demonstrate the relationship between route choice behaviour and emotional responses elicited by map symbols.