No consensus exists regarding which are the most effective mechanisms to promote household action on climate change. We present a meta-analysis of randomised controlled trials comprising 3,092,678 observations, which estimates the effects of behavioural interventions holding other factors constant. Here we show that behavioural interventions promote climate change mitigation to a very small degree while the intervention lasts (d = −0.093 95% CI −0.160, −0.055), with no evidence of sustained positive effects once the intervention ends. With the exception of recycling, most household mitigation behaviours show a low behavioural plasticity. The intervention with the highest average effect size is choice architecture (nudges) but this strategy has been tested in a limited number of behaviours. Our results do not imply behavioural interventions are less effective than alternative strategies such as financial incentives or regulations, nor exclude the possibility that behavioural interventions could have stronger effects when used in combination with alternative strategies.

Previous studies suggested that public trust in government is vital for implementations of social policies that rely on public's behavioural responses. This study examined associations of trust in government regarding COVID-19 control with recommended health behaviours and prosocial behaviours. Data from an international survey with representative samples (N=23,733) of 23 countries were analysed. Specification curve analysis showed that higher trust in government was significantly associated with higher adoption of health and prosocial behaviours in all reasonable specifications of multilevel linear models (median standardised β=0.173 and 0.244, P<0.001). We further used structural equation modelling to explore potential determinants of trust in government regarding pandemic control. Governments perceived as well organised, disseminating clear messages and knowledge on COVID-19, and perceived fairness were positively associated with trust in government (standardised β=0.358, 0.230, 0.055, and 0.250, P<0.01). These results highlighted the importance of trust in government in the control of COVID-19.

During the initial phase of the COVID-19 pandemic, U.S. conservative politicians and the media downplayed the risk of both contracting COVID-19 and the effectiveness of recommended health behaviors. Health behavior theories suggest perceived vulnerability to a health threat and perceived effectiveness of recommended health-protective behaviors determine motivation to follow recommendations. Accordingly, we predicted that—as a result of politicization of the pandemic—politically conservative Americans would be less likely to enact recommended health-protective behaviors. In two longitudinal studies of U.S. residents, political conservatism was inversely associated with perceived health risk and adoption of health-protective behaviors over time. The effects of political orientation on health-protective behaviors were mediated by perceived risk of infection, perceived severity of infection, and perceived effectiveness of the health-protective behaviors. In a global cross-national analysis, effects were stronger in the U.S. (N = 10,923) than in an international sample (total N = 51,986), highlighting the increased and overt politicization of health behaviors in the U.S.

Unsustainable patterns of tourist behavior produce a massive environmental burden. Nevertheless, it is unknown which behavioral strategies can be implemented to foster resource-efficient behavior in customers of leisure and travel services. This article aims to identify and summarize the evidence about the interventions which have been tested to promote sustainable hotel guest behavior. Electronic searches were performed in the main databases from inception to September 2016. Papers deemed eligible for inclusion were experimental field studies, reporting factual changes in guest behavior. The final sample was composed of nine papers comprising 13 studies in a total of 5,859 hotel stays. Results showed that all included interventions targeted towel reuse. Five different types of interventions were identified including environmental appeals, messages prompting commitment for conservation, donation to charity, social norms, and nudges. Only the last two forms of interventions (social norms: effect size [ES] = −0.25, 95% confidence interval [CI] = [−0.39, −0.12], p = .004 and nudges: ES = −0.43, 95% CI = [−0.72, −0.13], p = .009) showed significant positive effects in promoting towel reuse. Particularly regarding social norms, our work shows an effect weaker than reported in previous meta-analyses but consistent (low between-study heterogeneity) in producing modest increases in the levels of towel reuse.

This research examines how social networks contribute to the process of radicalization, building on work showing that obsessive (vs. harmonious) passion for a cause is linked to greater support for political violence. Study 1 ( N = 331) shows that obsessive (vs. harmonious) passion is related to affiliating with radical (vs. moderate) social networks, which in turn is associated with support for political violence. Study 2 ( N = 381) provides experimental evidence for this phenomenon, by showing that inducing an obsessive mindset produces a greater proclivity to connect with radical activists, which in turn is associated with greater support for political violence. Drawing from social network analysis, Study 3 ( N = 366) shows that network density intensifies obsessively passionate individuals’ affiliation to radical networks. The results offer insight into the group processes behind radicalization across different cultural contexts and ideologies.