The impact of self-affirmation on health-behavior change: a meta-analysis

Self-affirmation (induced by reflecting upon important values, attributes, or social relations) appears to reduce defensive resistance to health-risk information and increase subsequent readiness for health behavior change. However, these effects of self-affirmation have yet to be subjected to formal, quantitative integration. Consequently, the current article reports a meta-analysis of the impact of self-affirmation on outcomes at 3 key points in the process of health-behavior change: (a) message acceptance, (b) intentions to change, and (c) subsequent behavior.

The literature search identified 144 experimental tests of the effects of manipulating self-affirmation on these outcomes. Effect sizes were extracted and meta-analyzed.

Across 34 tests of message acceptance (N = 3,433), 64 tests of intentions (N = 5,564), and 46 tests of behavior (N = 2,715), random effects models indicated small but reliable positive 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.

The results suggest that deploying self-affirmation inductions alongside persuasive health information has positive effects, promoting message acceptance, intentions to change, and subsequent behavior. Though the effects are small in magnitude, they are comparable to those obtained in meta-analyses of other health-behavior change interventions. These findings are relevant to researchers and practitioners working to understand why people resist beneficial health information and how such resistance can be reduced.