Sustainable purchase intentions: The role of moral norm and social dominance orientation in the theory of planned behavior applied to the case of fair trade products

The fair trade business model represents a strategy to achieve some of the sustainable development goals. The studies reported in this paper examined the intention formation process concerning the purchase of food and non-food fair trade products. The theoretical framework is the theory of planned behavior (TPB), extended with an additional predictor, the moral norm, and an individual difference variable, the social dominance orientation (SDO). SDO is supposed to act as a background factor in the hypothesized TPB model and to be negatively associated with intention to buy fair trade products and its proximal antecedents (attitude, subjective norm, moral norm and perceived behavioral control). Considering the role of SDO within the TPB constitutes a novelty for the literature on socio-cognitive determinants of purchase intentions. Data were supplied by two convenience samples of Italian adults and analyzed via path analysis. The test of the original TPB provided further evidence for its efficacy. Moral norm showed a significant effect on intentions and its addition to the original TPB model led to an increase in the explained variance in intentions. Overall, SDO proved to be significantly and negatively associated with the intention's antecedents and showed the expected negative indirect effects on intention, mediated by its proximal predictors and moral norm. These findings help to improve the comprehension of the socio-psychological basis of behavioral intentions to engage in sustainable behaviors.