Scientific uncertainty as a moderator of the relationship between descriptive norm and intentions to engage in cancer risk-reducing behaviors.

This study examined motivational factors underlying six behaviors with varying levels of scientific uncertainty with regard to their effectiveness in reducing cancer risk. Making use of considerable within-subjects variation, the authors examined the moderating role of the degree of scientific uncertainty about the effectiveness of cancer risk-reducing behaviors in shaping relationships between constructs in the Integrative Model of Behavioral Prediction (Fishbein & Yzer, 2003 ). Using cross-sectional data (n = 601), the descriptive norm-intention relationship was stronger for scientifically uncertain behaviors such as avoiding BPA plastics and using a hands-free mobile phone headset than for established behaviors (e.g., avoiding smoking, fruit and vegetable intake, exercise, and applying sunscreen). This pattern was partially explained by the mediating role of injunctive norms between descriptive norm and intentions, as predicted by the extended Theory of Normative Social Behavior (Rimal, 2008 ). For behaviors more clearly established as an effective means to reduce the risk of cancer, self-efficacy was significantly more predictive of intentions to perform such behaviors. The authors discuss practical implications of these findings and theoretical insights into better understanding the role of normative components in the adaptation of risk-reduction behaviors.