Impulsive and/or planned behaviour: can impulsivity contribute to the predictive utility of the theory of planned behaviour?

This prospective study tested the prediction that impulsivity would contribute to the prediction of behaviour over and above key variables from an extended theory of planned behaviour (TPB) model. At Time 1, participants completed a questionnaire including measures of TPB constructs related to the avoidance of high-calorie snacks, in addition to measures of impulsivity and dietary restraint. At Time 2, participants (N=315) completed a questionnaire assessing their snacking behaviour over the previous 2 weeks. Results revealed that impulsivity significantly contributed to the prediction of behaviour over and above TPB constructs, with those higher in impulsivity being more likely to snack. This relationship was not moderated by behavioural intention. It is concluded that impulsivity might profitably be included alongside TPB variables when predicting behaviours that are not adequately characterized by careful, analytic, compensatory decision-making strategies.