Application of the Theory of Planned Behaviour to two dietary behaviours: Roles of perceived control and self-efficacy

Abstract

Objectives. This study examined the application of the Theory of Planned Behaviour (TPB) to two dietary behaviours with a particular focus on the roles of perceived control and self-efficacy as two components of the perceived behavioural control construct in the TPB. Methods. A total of 287 members of the general public completed questionnaires, one concerning the influence of TPB variables on intentions and behaviour for either eating five portions of fruit and vegetables per day (N = 144) or eating a low-fat diet (N = 143), and the second concerning actual eating behaviour one month later. In addition, the individual components of perceived behavioural control (perceived control and self-efficacy) and their determinant beliefs were examined. Results. For each behaviour, the TPB variables were found to be good predictors of intentions (fat intake, R2 = .637; fruit and vegetable intake, R2 = .572), although less good at predicting behaviour (fat intake, R2 = .185; fruit and vegetable intake, R2 = .321), with self-efficacy being consistently more predictive than perceived control. In addition, examination of their determinant beliefs revealed self-efficacy and perceived control to have difference bases. The conceptual and empirical distinctions between perceived control and self-efficacy are discussed.