Crystal Smit

An Integrated Model 3 49 behavioral predictors. Therefore, this study expands the social norms construct in the theory of planned behavior model by distinguishing between different types and sources of social norms. In addition, the study integrates insights from the social norms approach by adding direct relations between its constructs and individuals’ behaviors. A second possible explanation for the mixed evidence of theory of planned behavior in predicting dietary intake—thereby a promising way to integrate a different theoretical perspective—can be found in motivational theories of behavioral change. Notably, the theory of planned behavior does not incorporate an individual’s motivation to engage in a health-related behavior (Brown, Hagger, Morrissey, & Hamilton, 2018; Chatzisarantis, Hagger, Smith, & Sage, 2006). However, research based on self-determination theory shows that motivation, especially intrinsic motivation, is an essential determinant of behavioral change (Ryan et al., 2008), which is the tendency for individuals to engage in a behavior for their own sake, interest, or pleasure (Deci & Ryan, 1985). Intrinsic motivation to adopt healthier lifestyle patterns, such as healthy eating, fruit and vegetable consumption, and exercising, has been found to directly predict the actual adoption of these behaviors in the long term (e.g., Mata et al., 2009; Pelletier et al., 2004; Silva et al., 2011; Teixeira et al., 2015). Therefore, for this study, we posited a direct path between the motivational construct (i.e., intrinsic motivation) and actual dietary intake. Thus, the current state of knowledge indicates that there is a need for integrating different theoretical perspectives to determine which mechanism is the most predictive of dietary intake. As yet, it is uncertain how the main constructs in the three approaches compare to one another in predicting behavioral change. To this end, in the current study, we tested an integrated model, which is depicted in Figure 3.1. Based on theory of planned behavior research, the model tests the hypothesis that attitude, self-efficacy, and subjective norms predict behavioral intentions, which, in turn, predict subsequent changes in fruit, vegetable, and water consumption, either poorly or not at all. Based on social norms research,