How people update their beliefs about climate change: An experimental investigation of the optimism bias and how to reduce it

When receiving new information about their personal future, people usually update their beliefs selectively in response to good news and tend to disregard bad news, referred to as the optimism bias. Here, we investigated in two pre-registered experiments (N=278 and N=306) whether 1) such valence-dependent belief updating also underlies information processing in the context of climate change and 2) whether it can be altered by interventions informing about different aspects of climate change. To this end, we adapted a well-established belief update task to the context of climate change. In multiple trials, participants were asked about their beliefs about adverse consequences of climate change; subsequently, they were asked to update their initial beliefs in light of new information. Unlike beliefs about personal life events, both studies provided evidence against the hypothesis that people integrate good news about climate change more than bad news. Those participants who did so, though, had lower pro-environmental attitudes as well as higher trait optimism. After half of the trials, participants were randomized to one of four video-based interventions, each of which aimed at promoting a more accurate risk perception and increasing pro-environmental intentions. After the interventions, participants showed indeed a more accurate risk perception and women rather than men significantly increased their intentions for pro-environmental behavior. The results provide implications for effective climate change communication as they show that when facing the likely consequences of climate change, people adjust their risk perception accurately and increase their intentions to take actions to mitigate climate change.