Do decision biases predict bad decisions? Omission bias, naturalness bias, and influenza vaccination

Med Decis Making. Jul-Aug 2008;28(4):532-9. doi: 10.1177/0272989X07312723. Epub 2008 Mar 4.


Purpose: Numerous studies using hypothetical vignettes have demonstrated decision biases or deviations from utility theory. Do people who commit biases in questionnaire studies make worse real-world decisions than do less biased people?

Methods: Two hundred seventy university faculty and staff participated in a questionnaire study in which they reported whether they accepted a free influenza vaccine offered at their work place. Influenza vaccine acceptance was the measure of real-world decision making. Participants responded to 3 hypothetical scenarios. Two scenarios measured the omission bias and described a vaccine (scenario 1) and a medication (scenario 2) that prevented a negative health outcome but that itself could cause the negative health outcome. The omission bias is a preference for not vaccinating or medicating even when the vaccine/medication lowers the total risk of the negative outcome. A 3rd scenario measured the naturalness bias by presenting a choice between 2 chemically identical medications, one extracted from a natural herb and the other synthesized in a laboratory. Preference for the natural medication indicated the naturalness bias.

Results: The results indicated that a substantial proportion of participants exhibited these biases and that participants who exhibited these biases were less likely to accept the flu vaccine.

Conclusions: To the extent that declining a free flu vaccine is a worse real-world decision, people who demonstrate the naturalness and omission biases in hypothetical scenarios make worse real-world decisions.

MeSH terms

  • Adult
  • Aged
  • Bias*
  • Decision Making*
  • Female
  • Health Behavior
  • Humans
  • Influenza, Human / prevention & control*
  • Male
  • Middle Aged
  • Surveys and Questionnaires
  • Vaccination / psychology*