Mental contrasting for health behaviour change: a systematic review and meta-analysis of effects and moderator variables.

Mental contrasting is a self-regulation imagery strategy that involves imagining a desired future and mentally contrasting it with the present reality, which is assumed to prompt the individual to realise that action is required to achieve the desired future. Research has combined mental contrasting with implementation intentions (MCII) ('if-then' plans), which is hypothesised to strengthen the effects. A systematic review was conducted to evaluate the effectiveness of mental contrasting for improving health-related behaviours. A meta-analysis (N = 1528) using random effects modelling found a main effect of mental contrasting on health outcomes, adjusted Hedges' g = 0.28 (SE = .07), 95% CI [0.13-0.43], p < .001 at up to four weeks, and an increased effect at up to three months (k = 5), g = 0.38 (SE = 0.6), CI [0.20-0.55], p < .001. The combination of mental contrasting with implementation intentions (MCII; k = 7) showed a similar effect, g = 0.28, CI [0.14-0.42], p < .001. Mental contrasting shows promise as a brief behaviour change strategy with a significant small to moderate-sized effect on changing health behaviour in the short-term. Analysis on a small subset of studies suggested that the addition of implementation intentions (MCII) did not further strengthen the effects of mental contrasting on health behaviours, although additional studies are needed.