The more the merrier?

Author(s)
Lars Korn, Robert Böhm, Ana Paula Santana, Cornelia Betsch
Abstract

OBJECTIVE: During the COVID-19 pandemic, individuals in some countries had the option to choose from different vaccines, some of which were perceived as less favorable than others. Research on the decoy effect suggests that the preference for an option (target) increases when an inferior option (decoy) is added to the choice set. However, it is unknown whether the decoy effect occurs in vaccination decision making. METHOD: Two preregistered online experiments were conducted-a vignette experiment assessing hypothetical vaccination intentions (N = 1,268) and a behavioral experiment using an incentivized interactive vaccination game (N = 1,216)-and manipulated whether people were offered one vaccine (target) or two vaccines (target + decoy). Experiment 2 further tested four different types of decoys: the decoy was (a) a clone of the target or was inferior to the target in terms of (b) the probability of vaccine adverse events, (c) the severity of vaccine adverse events, or (d) vaccine effectiveness. The preference for the target vaccine (vs. nonvaccination) and the overall vaccine uptake were the main outcome variables. RESULTS: Both experiments showed substantial decoy effects. In Experiment 2, decoys with more severe vaccine adverse events or reduced effectiveness increased the preference for the target vaccine and the overall vaccine uptake. CONCLUSION: Taken together, the results suggest that health communication programs must be designed carefully, as multiple options serve as evaluative anchors and might induce preference shifts. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Organisation(s)
Department of Occupational, Economic and Social Psychology
External organisation(s)
Bernhard Nocht Institute for Tropical Medicine, Sigmund Freud Privatuniversität, University of Copenhagen
Journal
Health Psychology
Volume
44
Pages
119-128
No. of pages
10
ISSN
0278-6133
DOI
https://doi.org/10.1037/hea0001378
Publication date
09-2024
Peer reviewed
Yes
Austrian Fields of Science 2012
501021 Social psychology
ASJC Scopus subject areas
Psychiatry and Mental health, Applied Psychology
Sustainable Development Goals
SDG 3 - Good Health and Well-being
Portal url
https://ucrisportal.univie.ac.at/en/publications/4918b033-ac52-4f44-9af3-94fe1742040a