Invincibility threatens vaccination intentions during a pandemic.

Some people feel they are invincible to the novel coronavirus SARS-CoV-2 (COVID-19). They believe that being infected with COVID-19 would not be a serious threat to their health. While these people may or may not be correct in their personal risk assessment, we find that such perceived invincibility may undermine community efforts to achieve herd immunity. Multi-level analysis of survey respondents across 51 countries finds that perceived invincibility from COVID-19 is negatively associated with believing there is a need to prevent the spread of COVID-19 in one's community (n = 218,956) and one's willingness to inoculate against the disease (n = 71,148). These effects are most pronounced among individuals from countries lower in cultural collectivism (e.g., USA, UK, Canada) and highlight the need to consider the interplay of individual and cultural factors in our efforts to understand, predict, and promote preventative health behavior during a pandemic.

Attacker Deterrence and Perceived Risk in a Stackelberg Security Game.

In Stackelberg security games, a defender must allocate scarce resources to defend against a potential attacker. The optimal defense involves the randomization of scarce security resources, yet how attackers perceive the risk given randomized defense is not well understood. We conducted an experiment where attackers chose whether to attack or not attack targets protected by randomized defense schemes, the key treatment variable being whether the defender picks one target at random to guard or imperfectly guards all targets. The two schemes are expected-payoff equivalent, and when provided separately we found no effect of having one scheme or the other. Yet, when both are present, we found that subjects had a preference for the fixed scheme, a preference that cannot be reduced to differences in beliefs. Overall, our results suggest that understanding how individuals perceive risk is vital to understand the behavior of attackers.

Money Affects Theory of Mind Differently by Gender.

Theory of Mind (ToM)--the ability to understand other's thoughts, intentions, and emotions--is important for navigating interpersonal relationships, avoiding conflict, and empathizing. Prior research has identified many factors that affect one's ToM ability, but little work has examined how different kinds of monetary incentives affect ToM ability. We ask: Does money affect ToM ability? If so, how does the effect depend on the structure of monetary incentives? How do the differences depend on gender? We hypothesize that money will affect ToM ability differently by gender: monetary rewards increase males' motivation to express ToM ability while simultaneously crowding out females' motivation. This prediction is confirmed in an experiment that varies the structure of monetary rewards for correct answers in the Reading the Mind in the Eyes Test (RMET). RMET scores decrease for females and increase for males with individual payments, and this effect is stronger with competitively-structured payments. RMET scores do not significantly change when monetary earnings go to a charity. Whether money improves or hinders ToM ability, and, hence, success in social interactions, thus depends on the interaction of gender and monetary incentive structure.