Expanding the theory of planned behaviour: the role of social norms and group identification.

The purposes of the study were twofold. First, to explore the predictive power of the descriptive and group norms, when the effect of subjective norm had already been accounted for. Second, to investigate to what extent perceived group norm of a behaviourally relevant reference group would predict the intention to use contraception among those who identified strongly with the relevant reference group. The empirical data were generated from a sample of 354 sexually active female adolescents living in Addis Ababa, Ethiopia. The results revealed that subjective (injunctive) norm was the most important predictor of contraceptive intentions (β = .33, p<.001). In addition, descriptive norms (β = .20, p <.001) and (unexpectedly) group norm (β = .11, p <.035) exerted significant main effects upon intention. The study indicated that contraceptive intentions in Ethiopian adolescent girls were influenced more by 'social' (injunctive, descriptive) than 'personal' considerations (attitudes: β = .20, p <.001, and; PBC: β = .17, p<.001). However, none of the interaction terms between group identification and social influence variables were significant. Furthermore, collective-self did not emerge to have either a direct effect upon intention, or a moderation effect upon the social norms-intention relationships (as expected).