Combining self-affirmation, theory of planned behaviour messages, and implementation intentions to reduce students’ alcohol consumption

Abstract

Background. Messages based on the theory of planned behaviour (TPB) may fail to reduce students’ alcohol consumption because they are derogated/dismissed or because positive intentions are not translated into behaviour. Self-affirmation (the process of reflecting on cherished values) may decrease defensive processing of messages and implementation intentions may help people translate positive intentions into behaviour. Methods: One month before starting university, students (N=2,951) completed measures of their typical weekly alcohol consumption and were randomly assigned to condition in a 2 (self-affirmation) × 2 (TPB-based messages) × 2 (implementation intention) between-participants factorial design. Participants then completed measures of TPB variables towards binge drinking. Alcohol consumption was assessed six months later. Findings. Participants who received the TPB messages had significantly lower (i.e. less positive) scores on all TPB measures. Self-affirmed participants had significantly more positive attitudes, norms and intentions towards binge drinking. Participants who received the TPB messages consumed fewer units of alcohol and engaged in binge drinking less frequently at six-month follow-up; furthermore, these effects were mediated by TPB variables. All other main effects and interactions were non-significant. Discussion. The findings support the use of interventions based on the TPB to change students’ alcohol consumption. In contrast, the findings add to those of recent studies that have questioned the use of self-affirmation to reduce alcohol consumption in university students. The non-significant effect of forming implementation intentions may have been due to participants having limited knowledge and experience of the pressures to drink alcohol prior to starting university.