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.

The present research examined the motivational underpinnings of self-sacrifice. Based on the quest for significance theory, we argue that individuals are propelled to self-sacrifice for a cause to achieve a sense of self-worth, particularly after experiencing a loss of significance. Results from 6 studies yielded support for this hypothesis. Using a correlational design, Study 1 found that decreases in significance were associated with greater readiness for self-sacrifice. Study 2 experimentally demonstrated that experiences implicating negative self-worth increased the propensity for self-sacrifice controlling for positive and negative affect. Study 3 extended findings from Study 2 to a different context, and Study 4 demonstrated that failures in an important rather than a trivial domain increased individuals’ willingness to self-sacrifice for a cause. Study 5 found evidence that the search for significance mediates the relationship between significance loss and willingness to self-sacrifice. Finally, Study 6 provided evidence that self-sacrifice increased significance more than did pleasurable experiences, suggesting it is instrumental to significance restoration after loss. Findings are discussed in light of extant self-sacrifice literature and the quest for significance theory.

Adventure and excitement have often been invoked to explain why people engage in political violence, yet empirical evidence on the topic has thus far been anecdotal. The present research sought to fill this gap in knowledge by examining the role of sensation seeking in political violence and integrating this concept with Significance Quest Theory (Kruglanski, Chen, Dechesne, Fishman, & Orehek, 2009; Kruglanski et al., 2013). Extending prior research on violent extremism, Study 1 found that sensation seeking mediated the relation between meaning in life and willingness to self-sacrifice and support for political violence. Study 2 established temporal precedence of the variables in the mediation model, using a longitudinal design. Studies 3 and 4 experimentally replicated findings of Studies 1 and 2. In Studies 5a and 5b, we found that sensation seeking predicts support for a real life violent activist group. In Studies 6a and 6b, the positive evaluation of a violent activist group by individuals high in sensation seeking was explained by how exciting they perceived the group to be. Finally, Study 7 introduced an intervention targeting the sensation seeking motive by presenting participants with a peaceful (less exciting vs. exciting) activism group. As hypothesized, providing individuals high in sensation seeking with a peaceful yet exciting group mitigated their support for extreme behavior.

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.

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