The impact of probabilistic tornado warnings on risk perceptions and responses.

Many warnings issued to members of the public are deterministic in that they do not include event likelihood information. This is true of the current polygon-based tornado warning used by the American National Weather Service, although the likelihood of a tornado varies within the boundaries of the polygon. To test whether adding likelihood information benefits end users, two experimental studies and one in-person interview study were conducted. The experimental studies compared five probabilistic formats, two with color and three with numeric probabilities alone, to the deterministic polygon. In both experiments, probabilistic formats led to better understanding of tornado likelihood and higher trust than the polygon alone, although color-coding led to several misunderstandings. When the polygon boundary was drawn at 10% chance, those using probabilistic formats made fewer correct shelter decisions at low probabilities and more correct shelter decisions at high probabilities compared to those using the deterministic warning, although overall decision quality, operationalized as expected value, did not differ. However, when the polygon boundary was drawn around 30%, participants with probabilistic forecasts had higher expected value. The interview study revealed that, although tornado-experienced individuals would not shelter at 10% chance, they would take intermediate actions, such as information-seeking and sharing. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Reducing vaccine hesitancy by explaining vaccine science.

Vaccine hesitancy in the COVID-19 pandemic remained a problem long after mRNA vaccines became available. This may be due in part to misunderstandings about the vaccines, arising from complexities of the science involved. Two experiments, conducted on unvaccinated Americans at two periods postvaccine rollout in 2021, demonstrated that providing explanations, expressed in everyday language, and correcting known misunderstandings, reduced vaccine hesitancy compared to a no-information control group. Four explanations addressing misunderstandings about mRNA vaccine safety and effectiveness were tested in Experiment 1 (n = 3,787). Some included expository text while others included refutational text, explicitly stating and refuting the misunderstanding. Vaccine effectiveness statistics were expressed either as text or an icon array. Although all four explanations reduced vaccine hesitancy, the refutational format of those addressing vaccine safety (explaining the mRNA mechanism and mild side effects) was the most effective. These two explanations were retested individually and jointly in Experiment 2 (n = 1,476) later in the summer of 2021. Again, vaccine hesitancy was significantly reduced by all explanations despite differences in political ideology, trust, and prior attitudes. These results suggest that nontechnical explanations of critical issues in vaccine science can reduce vaccine hesitancy, especially when accompanied by refutational text. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

COVID-19: Risk perception, risk communication, and behavioral intentions.

Critical to limiting the spread of Coronavirus disease 2019 (COVID-19) and future pandemics is compliance with behavioral recommendations such as mask wearing and social distancing. Compliance may depend upon understanding the seriousness of the health consequences and the likelihood they will occur. However, the statistics that speak to these issues in an ongoing pandemic are complex and may be misunderstood. An online experiment with a U.S. sample tested the impact on perceived likelihood, trust, concern, behavioral intentions, and agreement with government response of numeric (mortality/infection percentage by age group) and gist expressions (which age group was smaller [mortality] or roughly equivalent [infected]). While the differences in risk perception and willingness to engage in activities between younger and older participants were small, "gist infection and mortality" increased willingness to wear a mask among younger participants. Government restrictions (e.g., social distancing) impacted willingness to engage is risk-reduction and risk-seeking activities. The biggest differences were due to political ideology. Although conservatives perceived similar levels of risk as did liberals, they were much less willing to engage in protective behaviors and support government policies. However, conservatives were affected by some risk communication formats and restrictions suggesting that future work should be aimed at this issue. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Reducing probabilistic weather forecasts to the worst-case scenario: anchoring effects.

Many weather forecast providers believe that forecast uncertainty in the form of the worst-case scenario would be useful for general public end users. We tested this suggestion in 4 studies using realistic weather-related decision tasks involving high winds and low temperatures. College undergraduates, given the statistical equivalent of the worst-case scenario (1 boundary of the 80% predictive interval), demonstrated biased understanding of future weather conditions compared with those given both bounds or no uncertainty information. We argue that this was due to an anchoring effect on numeric estimates, which were closer to the worst-case scenario than was warranted and increased linearly as the anchor became more extreme. In many situations tested here, anchoring in numeric estimates also extended to subsequent binary decisions, leading participants with the worst-case scenario to take action more often than did other participants. These results suggest that worst-case scenario forecasts can mislead the user. They appear to convince people that wind speeds will be higher and temperatures will be lower than what are indicated by the forecast. In addition, participants systematically "corrected" the forecast they were given. This effect was most prominent in the condition in which no uncertainty was provided, suggesting that people feel compelled to take uncertainty into account, even when it is not acknowledged by the forecast. Both the anchoring and correction biases were least evident when both bounds were provided, suggesting that balanced uncertainty leads to the best understanding of future weather conditions.