Shannon Duncan

Shannon Duncan
  • Doctoral Student

Contact Information

  • office Address:

    726.4 Jon M. Huntsman Hall
    3730 Walnut Street
    University of Pennsylvania
    Philadelphia, PA 19104


Shannon Duncan joined the Wharton Marketing Doctoral Program in fall 2019. Shannon received her BA in Psychology from Marist College, and her MS in Neuroscience from Columbia University. She served as the Associate Director of the Center for Decisions Sciences at Columbia University.

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  • Renato Frey, Shannon Duncan, Elke U. Weber (2022), Towards a typology of risk preference: Four risk profiles describe two thirds of individuals in a large sample of the U.S. population, Journal of Risk and Uncertainty .

  • Emma E. Levine and Shannon Duncan (2022), Deception and the marketplace of ideas, Consumer Psychology Review, 5 (1), pp. 33-50.

  • Jon M. Jachimowicz, Shannon Duncan, Elke U. Weber, Eric J Johnson (2019), When and why defaults influence decisions: a meta-analysis of default effects, Behavioural Public Policy.

    Abstract: When people make decisions with a pre-selected choice option – a ‘default’ – they are more likely to select that option. Because defaults are easy to implement, they constitute one of the most widely employed tools in the choice architecture toolbox. However, to decide when defaults should be used instead of other choice architecture tools, policy-makers must know how effective defaults are and when and why their effectiveness varies. To answer these questions, we conduct a literature search and meta-analysis of the 58 default studies (pooled n = 73,675) that fit our criteria. While our analysis reveals a considerable influence of defaults (d = 0.68, 95% confidence interval = 0.53–0.83), we also discover substantial variation: the majority of default studies find positive effects, but several do not find a significant effect, and two even demonstrate negative effects. To explain this variability, we draw on existing theoretical frameworks to examine the drivers of disparity in effectiveness. Our analysis reveals two factors that partially account for the variability in defaults’ effectiveness. First, we find that defaults in consumer domains are more effective and in environmental domains are less effective. Second, we find that defaults are more effective when they operate through endorsement (defaults that are seen as conveying what the choice architect thinks the decision-maker should do) or endowment (defaults that are seen as reflecting the status quo). We end with a discussion of possible directions for a future research program on defaults, including potential additional moderators, and implications for policy-makers interested in the implementation and evaluation of defaults.