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Attitudes and social norms are key social psychological concepts that have often been considered as independent determinants of human behavior. However, questions about the interplay between the two are somewhat of a blind spot in social psychology. In the present research, we test the hypothesis that when an important change in norms is involved, behavioral intentions will be shaped by a discrepancy between personal attitudes and the perceived group norm, that is the perception of other group members’ attitudes. This proposition is tested and supported across three studies in a context of the conversion to organic farming, a behavior indicative of a significant societal and behavioral change. Farmers who did convert to organic farming were those who perceive other farmers to hold less positive attitudes toward this environmentally‐friendly practice compared to their own (Study 1a & 1b, N = 1,023). Among conventional farmers, the intention to convert to organic farming is also predicted by a discrepancy between personal attitudes and the perceived group norm (Study 1b). Finally, among agricultural colleges’ students (Study 2, N = 280), the intention to become an organic farmer was influenced by an interaction between attitudes and perceived group norm and not only by independent effects of these two variables. The theoretical and practical implications of these findings for a better understanding of behavioral adaptation in times of social change are discussed.

In two studies about farming practices, the respondents who are particularly favorable to organic farming tend to have a higher intention to convert their farm to organic when they perceive other farmers as not very favorable to this practice. This intention can be considered as anticonformist, as it is in opposition to the general view of others. This article hypothesizes that this phenomenon can be explained by some biases on the perceptions of attitudes. It proposes an agent-based model which computes an intention based on the theory of reasoned action (TRA) and assumes some biases in the perception of others' attitudes according to the social judgment theory. It investigates the conditions on the model parameter values for which the simulations reproduce the features observed in the studies. The results show that perceptual biases are a possible explanation of anticonformist intentions.