Recent Publication(s)
"Behavioral nudges in social media ads show limited ability to encourage COVID-19 vaccination across countries" (corresponding author; w/ Olgahan Çat, Roman Hlatky, Huimin Li, and Daniel Nielson) (2024) PNAS Nexus. 3(8). DOI: 10.1093/pnasnexus/pgae189
Abstract: Behavioral nudges in Facebook ads reached nearly 15 million people across six diverse countries and, consequently, many thousands took the step of navigating to governments’ vaccine signup sites. However, none of the treatment ads caused significantly more vaccine signup intent than placebo uniformly across all countries. Critically, reporting the descriptive norm that 87% of people worldwide had either been vaccinated or planned vaccination—social proof—did not meaningfully increase vaccine signup intent in any country and significantly backfired in Taiwan. This result contradicts prominent prior findings. A charge to “protect lives in your family” significantly outperformed placebo in Taiwan and Turkey but saw null effects elsewhere. A message noting that vaccination significantly reduces hospitalization risk decreased signup intent in Brazil and had no significant effects in any other country. Such heterogeneity was the hallmark of the study: some messages saw significant treatment effects in some countries but failed in others. No nudge outperformed the placebo in Russia, a location of high vaccine skepticism. In all, widely touted behavioral nudges often failed to promote vaccine signup intent and appear to be moderated by cultural context.
"Behavioral nudges in social media ads show limited ability to encourage COVID-19 vaccination across countries" (corresponding author; w/ Olgahan Çat, Roman Hlatky, Huimin Li, and Daniel Nielson) (2024) PNAS Nexus. 3(8). DOI: 10.1093/pnasnexus/pgae189
Abstract: Behavioral nudges in Facebook ads reached nearly 15 million people across six diverse countries and, consequently, many thousands took the step of navigating to governments’ vaccine signup sites. However, none of the treatment ads caused significantly more vaccine signup intent than placebo uniformly across all countries. Critically, reporting the descriptive norm that 87% of people worldwide had either been vaccinated or planned vaccination—social proof—did not meaningfully increase vaccine signup intent in any country and significantly backfired in Taiwan. This result contradicts prominent prior findings. A charge to “protect lives in your family” significantly outperformed placebo in Taiwan and Turkey but saw null effects elsewhere. A message noting that vaccination significantly reduces hospitalization risk decreased signup intent in Brazil and had no significant effects in any other country. Such heterogeneity was the hallmark of the study: some messages saw significant treatment effects in some countries but failed in others. No nudge outperformed the placebo in Russia, a location of high vaccine skepticism. In all, widely touted behavioral nudges often failed to promote vaccine signup intent and appear to be moderated by cultural context.
Works in Progress (Selected)
International Development and Experimental Methods
"The Financial Consequences of International Organization Legitimacy" (w/ Mirko Heinzel and Daniel Nielson)
Abstract: Resource constraints on international organizations (IOs) have intensified as they have come under pressure from governments questioning their legitimacy. In response, IOs increasingly aim to diversify their resource base by raising funds from non-state actors and even from individual donors. However, little is known about the factors that motivate donations by the public. We argue that IO legitimacy matters and differentiate between: a) procedural, b) performance-based, and c) mandate-based legitimacy. We then analyze how legitimacy shapes donations to UNICEF in pre-registered survey, field and survey-based field experiments with more than 25 million Facebook users from five countries (Brazil, Egypt, India, Saudi Arabia, and the United Kingdom). Our results show that IO legitimacy does not appear to shape citizens’ real-world decisions to donate to IOs. The findings call for a deeper engagement with the real-world consequences of one of the most important concepts in the global governance literature.
"Experimental Evidence on the Individual Victim Effect" (w/ Mirko Heinzel and Daniel Nielson)
Abstract: The identifiable victim effect is one of the most prominent findings of the literature on charitable giving and ubiquitous in the practice of charity advertising. Yet studies testing it in the real world are scarce. This study evaluates the identifiable victim effect through a large number of social-media-based experiments conducted with more than 25 million people in Brazil, Egypt, India, Saudi Arabia, and the United Kingdom. Out of more than 100 experimental tests, not one shows any evidence that ads highlighting identifiable victims leads to any improvement in donation intent. Furthermore, we find some evidence that emphasizing statistical victims actually increases engagement more than identifiable victims. The results call into question the practical implications of one of the most prominent findings in academic research on charitable giving and should give pause to the large number of charities designing donation campaigns based on this research.
"The Financial Consequences of International Organization Legitimacy" (w/ Mirko Heinzel and Daniel Nielson)
Abstract: Resource constraints on international organizations (IOs) have intensified as they have come under pressure from governments questioning their legitimacy. In response, IOs increasingly aim to diversify their resource base by raising funds from non-state actors and even from individual donors. However, little is known about the factors that motivate donations by the public. We argue that IO legitimacy matters and differentiate between: a) procedural, b) performance-based, and c) mandate-based legitimacy. We then analyze how legitimacy shapes donations to UNICEF in pre-registered survey, field and survey-based field experiments with more than 25 million Facebook users from five countries (Brazil, Egypt, India, Saudi Arabia, and the United Kingdom). Our results show that IO legitimacy does not appear to shape citizens’ real-world decisions to donate to IOs. The findings call for a deeper engagement with the real-world consequences of one of the most important concepts in the global governance literature.
"Experimental Evidence on the Individual Victim Effect" (w/ Mirko Heinzel and Daniel Nielson)
Abstract: The identifiable victim effect is one of the most prominent findings of the literature on charitable giving and ubiquitous in the practice of charity advertising. Yet studies testing it in the real world are scarce. This study evaluates the identifiable victim effect through a large number of social-media-based experiments conducted with more than 25 million people in Brazil, Egypt, India, Saudi Arabia, and the United Kingdom. Out of more than 100 experimental tests, not one shows any evidence that ads highlighting identifiable victims leads to any improvement in donation intent. Furthermore, we find some evidence that emphasizing statistical victims actually increases engagement more than identifiable victims. The results call into question the practical implications of one of the most prominent findings in academic research on charitable giving and should give pause to the large number of charities designing donation campaigns based on this research.
Political Violence and Foreign Aid
"The Strategic Logic of Targeting of Aid by Rebel Groups During War" (w/ Michael Findley, Trey Billing, and David Backer)
Abstract: Rebels sometimes demonstrate remarkable sophistication in their strategies. In this paper, we report rich descriptive evidence from interviews, focus groups, and surveys with former commanders of the Lord’s Resistance Army (LRA), high-level leaders of the Ugandan Peoples’ Defence Forces (UPDF), elected government officials, and over 500 citizens in areas affected by the LRA. The interviews and surveys revealed that some of the most sophisticated rebel behavior occurred when rebels had high strategic aspirations and high material need. The LRA used targeted violence against civilians to strategically create need, for example, which effectively endogenized targetable aid allocation in the LRA’s interests. Commonly discussed tactics, such as abduction, had distinct aid targeting dimensions, as the LRA abducted people at the time of aid targeting to assist with transporting aid and obtaining intelligence rather than simply boosting fighting forces. The study thus illuminates conditions that motivate remarkable sophistication in otherwise rag-tag rebel groups and we discuss a number of implications for scholarship in this vein.
"The Role of Peacekeeping Operations in Reducing Violence in the Context of Foreign Aid" (w/ Bongjoo Kim)
Abstract: Since the launch of the United States Agency for International Development in 1961 and the release of “A Political Theory of Foreign Aid” (Morgenthau 1962), policy and academic communities have focused on foreign aid. Recent studies have found that an increase in foreign aid is related to a greater frequency of political violence. Aid can increase violence by motivating rebels to size up what they can take over via violence (Grossman 1991). More specifically, when violent actors expropriate aid or sabotage aid projects, this can result in more aid leading to more violence (Zürcher 2017). Additionally, drastic decrease in aid can lead to more violence (Nielson et al. 2011). Previous research analyzing the mechanisms of foreign aid’s effect on violence has focused on how the amount of aid varies the degree of political violence. However, this paper focuses on how the UN peacekeeping operations (PKOs) mitigate the degree of political violence toward civilians through the moderating effect of providing more support to rebels and civilians. Given that lower amounts of aid can be related to higher levels of civilian victimization (Nielson et al. 2011), we find that the presence of UNPKOs in the battlefield combined with a higher allocation of foreign aid is associated with reduced civilian victimization. This relationship can be further strengthened in the presence of PKOs that focus on specific mandates and agendas for foreign aid.
"An Empirical Test of Russian Influence in Asia and Eastern Europe" (w/ Olgahan Çat, Daniel Cowser, Nivedita Jhunjhunwala, Eoin Lazaridis Power, and Daniel Nielson)
Summary: We conduct online field experiments (i.e., A/B testing of Facebook ads) and survey experiments in Serbia, Turkey, India, Estonia, and Kazakhstan, focusing on their alignment with Russia. We examine whether ads prompting donations to Ukrainian refugees influence users' click-through rates. The ads feature either standard humanitarian messages or variations that highlight different humanitarian organizations and the countries' dependence on Russia for resources and military support.