Evaluating the usefulness of Protection Motivation Theory for predicting climate change mitigation behavioral intentions among a US sample of climate change deniers and acknowledgers.

Background: This paper summarizes data from 7 studies that used Protection Motivation Theory (PMT) to guide climate messaging with the goal of increasing climate-mitigating behavioral intentions. Together, the studies address 5 research questions. 1) Does PMT predict behavioral intentions in the context of climate change mitigation? 2) Does PMT work similarly for climate change deniers vs acknowledgers? 3) Are the effects of threat and efficacy additive or multiplicative? 4) Does adding measures of collective threat and efficacy improve the model accuracy for a collective problem like climate change? 5) Can threat and efficacy appraisals - and ultimately behavioral intentions - be shifted through climate messaging?

Methods: Seven online experiments were conducted on US adults (N = 3,761) between 2020 and 2022. Participants were randomly assigned to a control condition or to one of several experimental conditions designed to influence threat, efficacy, or both. Participants indicated their belief in climate change, ethnicity, gender, and political orientation. They completed measures of personal threat and efficacy, collective threat and efficacy, and behavioral intentions.

Results: Multiple regressions, ANCOVAs, and effect sizes were used to evaluate our research questions. Consistent with PMT, threat and efficacy appraisals predicted climate mitigation behavioral intentions, even among those who denied climate change. Different interactions emerged for climate deniers and acknowledgers, suggesting that in this context threat and efficacy are not just additive in their effects (but these effects were small). Including measures of collective threat and efficacy only modestly improved the model. Finally, evidence that threat and efficacy appraisals can be shifted was weak and inconsistent; mitigation behavioral intentions were not reliably influenced by the messages tested.

Conclusions: PMT effectively predicts climate change mitigation behavioral intentions among US adults, whether they deny climate change or acknowledge it. Threat appraisals may be more impactful for deniers, while efficacy appraisals may be more impactful for acknowledgers. Including collective-level measures of threat and efficacy modestly improves model fit. Contrary to PMT research in other domains, threat and efficacy appraisals were not easily shifted under the conditions tested here, and increases did not reliably lead to increases in behavioral intentions.