Degree of reasoned action predicts increased intentional control and reduced habitual control over health behaviors

Background: Research is needed to understand factors that attenuate the association between habits and health behavior performance. Purpose: We tested whether degree of reasoned action (DRA) moderates both intention-behavior and habit-behavior relations. DRA was defined by how well cognitions predict behavioral intentions, and was measured by the respective within-participants multiple correlation (R). Methods: Four studies were undertaken. Two pilot studies established the validity of our measure of DRA. Studies 1 (N = 663) and 2 (N = 1014) were prospective surveys of eight and six health behaviors, respectively. Intentions were measured via standard scales and habits were indexed by measures of frequency of performance × context stability. Results: In both studies, habits attenuated the predictive validity of intention. However, well-reasoned intentions better predicted health behaviors than poorly reasoned intentions, and habits offered weaker prediction of behavior when intentions were well reasoned. Three-way DRA × intention × habit interactions were also observed. Habits best predicted health behaviors when intentions were weak and poorly reasoned (Study 1), or offered poorest prediction of health behaviors when intentions were both strong and well-reasoned (Study 2). Conclusions: Degree of reasoned action predicts increased intentional control and reduced habitual control over multiple health behaviors