A psychosocial model of drinking amongst young people and the effects of brief interventions.

The Theory of Planned Behaviour (TPB) is an attitude-behaviour model that has received
considerable research attention for a plethora of health topics. However, it has received little
attention in the alcohol use arena among young people, particularly adolescents. The main aim of
the thesis is to test the 'augmented model of the TPB that encapsulates more theory driven
conceptualisations of the social norm component. The behaviour of interest is alcohol consumption.
The second aim of the thesis is to utilise and test the effectiveness of brief interventions. The
population of interest is young people - namely university undergraduates and adolescents. The
thesis is divided into two broad sections.
First, two studies that provide data to support the usefulness of the TPB as a predictor of
alcohol consumption intentions and behaviour are reported. Evidence is submitted supporting the
inclusion of wider conceptualisations of the social norm component to aid in the prediction of this
behaviour, as well as for the inclusion of past behaviour as an important determinant of future
behaviour. The data support the distinction between behavioural intentions and behavioural
willingness for younger and older adolescents.
Second, the effectiveness of brief intervention studies is reported. The primary aim of the
interventions was to reduce alcohol consumption in adolescents and undergraduates. A secondary
aim of the research was to utilise the augmented TPB as an evaluation tool to establish how
effective interventions work. The first intervention study examined the effect of personalised
feedback in reducing the number of weekly units consumed among university undergraduates,
whilst exploring the role of social cognition variables as moderators of efficacy. Although the
feedback intervention was effective at reducing behaviour, contrary to predictions, social cognition
variables did not moderate the intervention; however, past behaviour was shown to moderate the
relationship between condition and behaviour scores. The second intervention study examined the
effect of resistance skills training in reducing drinking behaviour among adolescents. It was shown
that none of the augmented TPB variables were mediators.
The conclusions that can be drawn from these studies and their implications for the existing
research literature are discussed.