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Studies in Behavioral Economics


Is an option especially tempting when it is both immediate and certain? To study the effect of risk on present bias, my first chapter presents an online experiment in which workers allocate about thirty minutes of real-effort tasks between two weeks. I compare choices made two days before the first workday against choices made when work is imminent. In baseline treatments, one choice is randomly implemented; meanwhile, one treatment implements a particular allocation with certainty. By assuming that effort costs are not affected by the mechanism (and thus independent of risk preferences), my novel design permits estimation of present bias using a decision with a consequence both immediate and certain. I find the average intensity of present bias is far greater under certainty than under risk. I find no evidence that present bias is more pervasive among individuals, suggesting instead that present-biased individuals become more myopic.

COVID-19 vaccination has both private and public benefits. The second chapter, co-authored with Gary Charness and David Levine, asks whether social preferences—concerns for the well-being of other people—influence one's decision regarding vaccination. We measure these social preferences for 549 online subjects: We give each subject $4 to play a public-goods game and make contributions to public welfare. To the extent that one gets vaccinated out of concern for the health of others, contribution in this game is analogous to an individual's decision to obtain COVID-19 vaccination. We collect COVID-19 vaccination history separately to avoid experimenter-demand effects. We find a strong result: Contribution in the public-goods game is associated with greater demand to voluntarily receive a first dose, and thus also to vaccinate earlier. Compared to a subject who contributes nothing, one who contributes the maximum ($4) is 48% more likely to obtain a first dose voluntarily in the four-month period that we study (April through August 2021). People who are more pro-social are indeed more likely to take a voluntary COVID-19 vaccination.

Widespread vaccination is certainly a critical element in successfully fighting the COVID-19 pandemic. The third chapter, co-authored with Gary Charness and David Levine, applies theories of social identity to design targeted messaging to reduce vaccine hesitancy among groups with low vaccine uptake, such as African Americans and political conservatives. We conducted an online experiment from April 7th to 27th, 2021, that oversampled Black, Latinx, conservative, and religious U.S. residents. We first solicited the vaccination status of over 10,000 individuals. Of the 4,609 individuals who reported being unvaccinated, 4,190 enrolled in our covariate-adaptive randomized trial. We provided participants messages that presented the health risks of COVID-19 to oneself and others; they also received messages about the benefits of a COVID-19 vaccine and an endorsement by a celebrity. Messages were randomly tailored to each participant's identities—Black, Latinx, conservative, religious, or being a parent. Respondents reported their intent to obtain the vaccine for oneself and, if a parent, for one's child. We report results for the 2,621 unvaccinated respondents who passed an incentivized manipulation check. We find no support for the hypothesis that customized messages or endorsers reduce vaccine hesitancy among our segments. A post hoc analysis finds evidence that a vaccine endorsement from Dr. Fauci reduces stated intent to vaccinate among conservatives. We find no evidence that tailoring public-health communication regarding COVID-19 vaccination for broad demographic groups would increase its effectiveness. We recommend further research on communicators and endorsers, as well as incentives.

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