Current Research

2013-07-10 13.22.39

Nudge to Health

Gretchen Chapman, Jeff DeWitt

How can we harness what we know about the psychology of decision making and use it nudge people toward healthier behaviors?  For example, some studies used the default effect to encourage vaccination.  Clinic patients get a letter telling them that they could make an appointment for a flu shot (default=no appointment) or saying that they had been automatically scheduled for an appointment which they could cancel (default= appointment). Vaccination rates were higher in the second group.  In some related studies we examined how the default effect influenced dietary choices.  In another set of studies, we employed reference points to increase the amount of physical activity that people got.  Participants wore pedometers to monitor the amount that they walked.  The walked more if they were given high goals (even unrealistically high goals) rather than low goals, and they walked more when they were told how their walking compared with that of others in the study compared to when they were not given this social comparison information.  See a video here.

  • Chapman, G.B., Li, M., Colby, H., & Yoon, H. (2010).  Opting in versus opting out of influenza vaccination. JAMA, 304(1), 43-44.
  • Li, M. & Chapman, G.B. (2013).  Nudge to health: Harnessing decision research to promote health behavior.  Social Psychology Compass, 7/3, 187-198.
  • Chapman, G.B., Colby, H., Convery, K., & Coups, E.J. (2015). Goals and social comparisons promote walking behavior. Medical Decision Making.
  • Chapman, G.B., Li, M., Leventhal, H., & Leventhal, E.A. (under review). Do defaults promote, or simply displace vaccination?
  • Li, M., Colby, H., & Chapman, G.B. (under review). Do defaults change what people eat? Dietary defaults and their boundaries.

Vaccination Decision

Gretchen Chapman

Vaccination decisions (such as whether or not to get an annual flu shot) represent a health behavior that captures multiple attributes of interest to decision researchers.  Vaccination has delayed benefits (vaccinate now to avoid later infection) and risky outcomes (you’ll likely avoid infection even if you don’t vaccination).   And vaccination entails social dynamics — vaccinated individual benefit unvaccinated individuals through herd immunity, and unvaccinated individuals can free ride on those who are vaccinated.  We explore vaccination decisions in questionnaire studies, including a recently completed internet survey in 8 countries.

  • Chapman, G.B., Li, M., Vietri, J.T., Ibuka, Y., Thomas, D., Yoon, H. & Galvani, A. (2012).  Using game theory to examine incentives in influenza vaccination behavior. Psychological Science, 23(9), 1008-1015.
  • Betsch, C, Böhm, R., & Chapman, G.B. (2015). Interventions to counter vaccine hesitancy – Using behavioral insights to increase vaccination policy effectiveness. Policy Insights from the Behavioral and Brain Sciences, 2(1), 61-73.
  • Chapman, G.B., Block, C., Millard, F., & Galvani, A.P. (under review). Parents of young children more likely to be vaccinated against influenza.
  • Taylor, E., Atkins, K., Medlock, J., Li, M., Chapman, G.B., & Galvani, A. (2015). Cross-cultural household influence on vaccination decisions. Medical Decision Making.

Dietary Decisions

Peggy Policastro, Gretchen Chapman

 Principles of decision science can be used to structure dining environments in a way that fosters healthy eating.  Using Rutgers Dining Services venues as our laboratory, we conduct experiments on the factors that influence diners to choose water instead of soda or to select healthier ingredients for a sandwich.  We have found that restructuring the order slip to highlight healthier options increases slightly the frequency with which those options are selected.  A simple prompt is often sufficient to get people to select a smaller serving or a healthier alternative.  In one study we asked students to precommit to use take-out service less frequently to see if that self control device would effectively change behavior.

  • Policastro, P., Smith, Z., & Chapman, G.B. (2015). Put the healthy item first: Order of ingredient listing influences consumer selection. Journal of Health Psychology.

Intertemporal Choice

Dan Wall, Gretchen Chapman

Many decisions involve trade-offs between immediate outcomes and more delayed outcomes. Future outcomes are inherently uncertain, and risk can affect how decision makers discount future outcomes.  In this projects we explore how two different kinds of risk affect intertemporal choice:  outcome uncertainty (uncertainty about whether or not you will bet the outcome) and amount uncertainty (uncertainty about how much you will get).  Participants make choices (sometimes for real outcomes) which we compare to our predictions.


Social Preferences & Social Norms

Jeff DeWitt, Gretchen Chapman

Although some decisions are driven primarily by self-interest, many are influenced by the impact our decisions will have on the outcomes of others.  Many people donate blood, give gifts, or engage in prosocial behavior that does not benefit them directly.  These actions may be driven by concern for other’s outcomes or by a desire to conform to social norms.  We explore the mechanism that drive seemingly prosocial behavior by using laboratory games such as the dictator game and the prisoner’s dilemma and by conducting field studies where we examine real-world behaviors such as blood donation.


Social Norms & Social Behavior

Steven Jones, Gretchen Chapman

How do messages about descriptive and injunctive social norms influence health behavior (e.g., getting vaccinated) or prosocial action (e.g., donating to a charity)?  We explore how the influence of descriptive vs. injunctive social norm messages may be moderated by the source of the message (peer vs. authority figure).  In a related project, we explore how subtle changes to the wording of a health prompt might influence how long-lasting the effects of the prompt are.


Scarcity, Fairness, and Generosity

Chris Boyce-Jacino, Gretchen Chapman

We use laboratory games such as the ultimatum game and the prisoner’s dilemma to explore decision makers’ preferences for fairness and generosity.  We examine how experiences prior to the game or within the game change these preferences.  For example, we are currently exploring the idea that experiencing scarcity will make decision makers more generous in a situation where generosity can trigger reciprocity.






Department of Psychology, Rutgers, the state university of New Jersey

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