Do Self-Incentives and Self-Rewards Change Behaviour? A Systematic Review and Meta-Analysis.

Background: Behaviour change techniques are considered to be the building blocks of behaviour change interventions, but it is not yet clear which are the most effective behaviour change techniques. Aim: This systematic review and meta-analysis is the first to evaluate the unique effects of self-incentives (“plan to reward oneself in the future”) and self-rewards (“prompt self-reward”) on behaviour change.Method: Electronic databases were searched (including backwards and forwards searching) alongside manual searching of systematic reviews and online research registers. Self-incentives and self-rewards were coded using the behaviour change technique taxonomy v1. Random-effects models assessed the unique effects of self-incentives and self-rewards on behaviour change compared to a comparator. Results: 1400 papers were retrieved with ten studies meeting the inclusion criteria. Despite contacting authors, effect sizes could only be computed for seven studies. The pooled effect size for self-incentive (k = 4; N = 235) was negative, close to zero and statistically non-significant (d = -0.06, CI = -0.71 to 0.60). In contrast, the pooled effect size for self-rewards (k = 3; N = 929) was positive and statistically significant (d = 0.16, CI = 0.03 to 0.29).Conclusions: The dearth of studies evaluating the unique effects of self-incentives and self-rewards on behaviour change means that the findings should be interpreted with caution. Further research is required to establish whether: (a) self-incentives truly exert negative effects on behaviour change, (b) self-rewards represent an effective behaviour change technique, and (c) self-incentives or self-rewards need to be deployed alongside other behaviour change techniques to support behaviour change.