Adolescent soft drink consumption, television viewing and habit strength. Investigating clustering effects in the Theory of Planned Behaviour.

Clustering refers to the co-occurrence of behaviour and may be particularly relevant in light of the present obesity epidemic. Since evidence regarding clustering of motivational and habitual constructs within the framework of the Theory of Planned Behaviour (TPB) is limited, clustering effects of TPB cognitions and habit strength regarding soft drink consumption and television viewing were studied in a sample of Dutch adolescents (n = 312; mean age = 14.62; SD = 1.62) using cross-sectional data. Results showed that not only soft drink consumption and television viewing cluster (r = .42), but also their intentional (r = .36) and habitual (r = .37) constructs. Furthermore, unmediated effects were found between habit strength and its respective behaviour, whereas habit strength was associated with its clustered behaviour through decreased perceptions of controllability. Our findings suggest that interventions that aim to change habitual soft drink consumption and television viewing may need to incorporate an environmental component, as well as explore the potential usefulness of synergistic effects of incorporating multiple clustered behaviours, as well as their corresponding beliefs and habits in health behaviour change interventions.