Reluctance to vaccinate: Omission bias and ambiguity

Ilana Ritov*, Jonathan Baron

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

541 Scopus citations


Subjects are reluctant to vaccinate a (hypothetical) child when the vaccination itself can cause death, even when this is much less likely than death from the disease prevented. This effect is even greater when there is a ‘risk group’ for death (with its overall probability held constant), even though the test for membership in the risk group is unavailable. This effect cannot be explained in terms of a tendency to assume that the child is in the risk group. A risk group for death from the disease has no effect on reluctance to vaccinate. The reluctance is an example of omission bias (Spranca, Minsk & Baron, in press), an overgeneralization of a distinction between commissions and omissions to a case in which it is irrelevant. Likewise, it would ordinarily be prudent to find out whether a child is in a risk group before acting, but in this case it is impossible, so knowledge of the existence of the risk group is irrelevant. The risk‐group effect is consistent with Frisch & Baron's (1988) interpretation of ambiguity.

Original languageAmerican English
Pages (from-to)263-277
Number of pages15
JournalJournal of Behavioral Decision Making
Issue number4
StatePublished - 1990
Externally publishedYes


  • Ambiguity
  • Omission bias
  • Vaccination


Dive into the research topics of 'Reluctance to vaccinate: Omission bias and ambiguity'. Together they form a unique fingerprint.

Cite this