Is It Riskier to Meet 100 People Outdoors or 14 People Indoors? Comparing Public and Expert Perceptions of COVID-19 Risk

Public Significance Statement This study shows that, in Summer 2020, medical experts placed greater weight on environmental factors (such as being indoors or outdoors) than the general public when judging the risk of contracting COVID-19. The study also shows that the public perceived the risk of contracting COVID-19 to be lower when potential exposure to the virus was needed to avoid an alternative risk (e.g., using busy public transport to attend an urgent medical appointment). People have limited capacity to process and integrate multiple sources of information, so how do they integrate multiple contextual risk factors for Coronavirus disease (COVID-19) infection? In June 2020, we elicited risk perceptions from a nationally representative sample of the public (N = 800) using three psychologically-distinct tasks. Responses were compared to a sample of medical experts who completed the same tasks. Relative to experts, the public perceived lower risk associated with environmental factors (such as whether a gathering takes place indoors or outdoors) and were less inclined to treat risk factors as multiplicative. Our results are consistent with a heuristic simply to "avoid people" and with a coarse (e.g., "safe or unsafe") classification of social settings. A further task, completed only by the general public sample, generated novel evidence that when infection risk competes with risk in another domain (e.g., a different medical risk), people perceive a lower likelihood of contracting the virus. These results inform the policy response to the pandemic and have implications for understanding differences between expert and lay perception of risk.