Causality in the Theory of Planned Behavior.

The theory of planned behavior proposes that behavior is predicted by behavioral intention which is, in turn, predicted by three base components: attitudes toward the behavior, subjective norms regarding the behavior, and perceived control over the behavior. Implied within this theory is that each of the three base components influence intentions, solely in that direction. However, despite being one of the most widely used theories in many areas of psychology and health sciences, few studies have tested this basic premise. Might causal influence also flow in a reverse-causal direction from intentions back to the base components? This causal sequence was tested and supported by a correlational study, a lab-based experiment, and a quasi-experimental field study. This demonstration of reverse-causal relations from intentions to the base components suggests that the theory of planned behavior should be modified to include reciprocal causal relations.