Use of refillable bottles by Italian students and non-student adults: testing an extended model of the theory of planned behavior

This study investigated the psychosocial determinants of using refillable bottles for Italian students and non-student adults. It tested the theory of planned behavior (TPB), integrated with past behavior and self-identity as a person who uses refillable bottles. So far, few studies exist on this specific behavior, which may have a relevant impact on plastic waste reduction and sustainability issues. The study adopted a two-wave prospective online survey design. At Time 1, measures of TPB core constructs (i.e., attitude, subjective norm, perceived behavioral control and intention), past behavior and self-identity were detected. At Time 2, the self-report target behavior of using refillable bottles was measured. The data were analyzed via structural equation modeling. The results confirmed that the extended TPB adequately explained and predicted both intention (73% of variance) and target behavior (68% of variance). At Time 1, attitude, perceived behavioral control and self-identity were associated with intention, which, in turn, was significantly linked to refillable bottle use at Time 2. Past behavior predicted intention at Time 1 and target behavior at Time 2, both directly and indirectly. A multi-group analysis showed that the effect of self-identity on intention was stronger in non-student adults than in the student sample. The results offer insights into designing interventions to promote the investigated pro-environmental behavior.