Two challenges to a moral extension of the theory of planned behavior: moral norms and just world beliefs in conservationism

The present paper employs a new approach to testing the sufficiency of the theory of planned behavior (TPB) in understanding intentions to behave ecologically. Based on two panel surveys, we explore whether the TPB should be extended into the moral domain by applying an aggregated, more reliable, and thus, more valid version of the TPB. The sample used consisted of 895 randomly selected German-speaking Swiss. A year later, 823 people returned a second questionnaire. Structural equation analyses reveal that attitude, subjective norms, and perceived behavioral control jointly account for 81% and 80% of people's intention. This, in turn, predicts 51% and 48%, respectively, of people's behavior variance. The explanatory power of the TPB is not improved by adding moral norms or by including two Just World Belief scales.