Quitting Smoking: Applying an Extended Version of the Theory of PlannedBehavior to Predict Intention and Behavior1

This study examined the ability of the theory of planned behavior (TPB)to predict students' intentions to quit smoking and the subsequent behavior6 months later. In addition, the impact of past behavior, moral norms, self-identity, group identity, and positive/negative anticipated affect was examined. The intention-behavior relationship was examined by dividing the sample in four subgroups: inclined actors/abstainers and disinclined actors/abstainers. Analyses were based on data from a prospective sample of 698 smokers. Attitude, subjective norms, and perceived behavioral control accounted for 36% (adjusted R2) of the variance in intentions. Moral norms, positive anticipated affect, group identity, and past behavior added 9% (adjusted R2) to the explained variance in intention, beyond the effect accounted for by the TPB components. Subsequent behavior was predicted by intentions (adjusted R2= .12). Past behavior, moral norms, self-identity, and the Past Behavior x Intention and Moral Norm x Negative Affect interactions explained an additional 9% (adjusted R2) of the variance in behavior. Inclined abstainers constituted the main source of the discrepancy between intention and behavior.