Temporal stability of behavioural intention as a moderator of intention-health behaviour relationships

Seven prospective studies of health behaviours containing eight prospective datasets testing the moderating role of intention stability on intention-behaviour and past behaviour-behaviour relationships were examined within the context of the Theory of Planned Behaviour. The measure of intention stability was based on lack of change in intentions between the two measurement time points. Across different behaviours, samples and time frames more stable intentions were associated with intentions at time 1 that were stronger predictors of behaviour at time 2. Intention stability did not consistently moderate the past behaviour-behaviour relationship. Across studies the frequency-weighted mean correlation between intentions and behaviour was substantially greater for stable (r(+) = 0.60) compared to unstable (r(+) = 0.27) intentions (Z(difference) 6.65, p < 0.001). The past behaviour-behaviour correlation was also stronger for stable ( r(+) = 0.50, p < 0.001) compared to unstable (r(+) = 0.34, p < 0.001) intentions (Z(difference) 3.12, p < 0.01). Perceived behavioural control was the variable most strongly related to stable intentions. Implications for understanding the role of health cognitions in the performance of health behaviour are discussed.