Dismissing “Don’t Know” Responses to Perceived Risk Survey Items Threatens the Validity of Theoretical and Empirical Behavior-Change Research

Erika A. Waters, Marc T. Kiviniemi, Jennifer L. Hay, Heather Orom

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Since the middle of the 20th century, perceptions of risk have been critical to understanding engagement in volitional behavior change. However, theoretical and empirical risk perception research seldom considers the possibility that risk perceptions do not simply exist: They must be formed. Thus, some people may not have formulated a perception of risk for a hazard at the time a researcher asks them, or they may not be confident in the extent to which their perception matches reality. We describe a decade-long research program that investigates the possibility that some people may genuinely not know their risk of even well-publicized hazards. We demonstrate that indications of not knowing (i.e., “don’t know” responses) are prevalent in the U.S. population, are systematically more likely to occur among marginalized sociodemographic groups, and are associated with less engagement in protective health behaviors. “Don’t know” responses are likely indications of genuinely limited knowledge and therefore may indicate populations in need of targeted intervention. This body of research suggests that not allowing participants to indicate their uncertainty may threaten the validity and generalizability of behavior-change research. We provide concrete recommendations for scientists to allow participants to express uncertainty and to analyze the resulting data.

Original languageEnglish
Pages (from-to)841-851
Number of pages11
JournalPerspectives on Psychological Science
Issue number3
StatePublished - May 2022

Bibliographical note

Funding Information:
We thank Caitlin Biddle, Kimberly Kaphingst, Yuelin Li, and Elizabeth Schofield for their critical insights into the causes and consequences of DK responding. Our work has greatly benefitted from their efforts. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Informed consent was obtained from all individual participants included in the study.

Publisher Copyright:
© The Author(s) 2021.


  • judgment
  • quantitative methodology
  • reasoning
  • risk perception
  • social cognition
  • socioeconomic status
  • thinking

ASJC Scopus subject areas

  • Psychology (all)


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