Interaction effects in the theory of planned behavior: The interplay of self-identity and past behavior

This research used a revised theory of planned behavior (TPB) model, which incorporated self-identity and past behavior-and the interaction between these constructs-in order to improve the model's predictive power in relation to consumer behavior (purchasing one's preferred beer). At Time 1, respondents (N = 108) completed measures of attitudes, perceived behavioral control, subjective norm, self-identity, past behavior, and intentions. Behavior was assessed 1 week later. All predictors were positively related to intentions. Self-identity and past behavior interacted to influence intentions: Self-identity had a stronger influence on intentions at low, rather than high, levels of past behavior. Intentions and past behavior were predictive of Time 2 behavior. These findings emphasize the need to consider identity issues in the TPB.