A dyadic approach to the Theory of Planned Behaviour: examining parent and teenager eating behaviours


  • K. Joyal-Desmarais
  • R. Lenne
  • L. Auster-Gussman
  • C. Huelsnitz
  • W. Johnson
  • M. Panos
  • J. Simpson
  • A. Rothman


Background: The Theory of Planned Behaviour (TPB) provides an intrapersonal framework for understanding how a person’s beliefs influence behaviour. We situate the TPB in a dyadic framework and examine how teenagers’ and parents’ beliefs about eating may influence not only their own behaviour (“actor effectsâ€), but also each other’s behaviour (“partner effectsâ€). Methods: Our sample consisted of 1646 parent-teen dyads from the Family Life, Activity, Sun, Health, and Eating (FLASHE) study conducted by the National Cancer Institute. Each person reported on their consumption of: (1) fruits/vegetables, and; (2) junk foods/sugary drinks. Additionally, each person reported on their attitude, subjective norm, and perceived behavioural control (PBC) for both types of behaviour (a measure of behavioural intention was not completed). Findings: Dyadic path analyses indicated actor effects, such that each individual’s beliefs (attitude, norm, PBC) significantly predicted their own eating behaviour (β=0.061-0.308, p<.05). Furthermore, teenager and parent beliefs significantly predicted each other’s fruit/vegetable consumption, and the magnitude of these partner effects was similar from teen-to-parent (β=0.092-0.107, p<.05), as from parent-to-teen (β=0.083-0.098, p<.05). For junk food/sugary drink consumption, parents appeared to have a greater impact on their teen’s behaviour than vice versa. Discussion: By approaching TPB variables from a dyadic perspective, we were able to show that a person’s behaviour is associated with both their own beliefs and the beliefs held by an important other (i.e., a parent/child). These findings may help expand our understanding of the determinants of people’s behaviour and lead to the identification of new intervention strategies.