The Impact of Self-Affirmation on Health-Behavior Change: a Meta-Analysis

Abstract

Self-affirmation (eg induced by reflecting upon important values) may reduce defensive resistance to information and increase readiness for change. However, these effects have yet to be subjected to quantitative review. We report a meta-analysis of the impact of self-affirmation on outcomes at 3 key points in the process of health-behavior change: message acceptance, intentions to change, and subsequent behavior. Methods. The literature search identified 144 tests of the effects of self-affirmation on outcomes. Effect sizes were extracted and meta-analyzed. Findings. Random effects models indicated small but reliable +ve effects of self-affirmation on each outcome: acceptance, d=.17 (CI=.03 to.31), intentions, d=.14 (CI=.05 to .23), behavior, d=.32 (CI=.19 to .44). Findings held across a range of health problems and behaviors. Discussion. Deploying self-affirmation inductions alongside persuasive health information has +ve effects, with effect sizes comparable to ones obtained in meta-analyses of other health-behavior change interventions. The findings are relevant to those working to understand why people resist beneficial information and how such resistance can be reduced.