Foundational knowledge - Traditional Theories and Models of Behavior Change
The theories most used in lifestyle interventions with good scientific results are Social Cognitive Theory (SCT), Theory of Planned Behavior (TPB), The Health Belief Model (HBM) and the Trans-Theoretical Model (TTM). Read the compilation in this book!
3. Theory of Planned Behavior (TPB)
Theory of Planned Behavior (TPB) intends to explain all behaviors over which people can employ self-control, and it is an extension of the Theory of Reasoned Action (TRA) (Ajzen, 1991). The key component of the model is behavioral intent. Behavioral intentions are shaped by the attitude about the likelihood of the behavior to have the expected outcome and by the subjective evaluation of the risks and benefits of the desired outcome (Ajzen, 1991). The TPB implies that achieving a specific behavior depends on motivation (intention) and ability (behavioral control). It makes the difference between three types of beliefs - behavioral, normative, and control. The TPB contains six constructs that collectively represent people’s actual control over the behavior.
- Attitudes refer to a person's degree to have a favorable or unfavorable evaluation of the behavior of interest. It requires the person to consider the outcomes of performing the behavior (Ajzen, 1991).
- Behavioral intention refers to the motivational factors that influence a given behavior. If the intention to perform the behavior is strong, the behavior will most likely be performed (Ajzen, 1991).
- Subjective norms refer to the thoughts about whether most people approve or disapprove of the behavior. It relates to a person's beliefs about whether peers and people of importance think they should engage in the behavior (Ajzen, 1991).
- Social norms refer to the specific behaviors of a group of people or a larger cultural context. Social norms are considered usually to dictate in a group of people (Ajzen, 1991).
- Perceived power refers to the perceived presence of factors that may facilitate or impede the performance of a behavior. Perceived power contributes to a how a person perceives behavioral control over each of those factors (Ajzen, 1991).
- Perceived behavioral control refers to a person's perception of how easy or difficult is to perform a specific behavior. Perceived behavioral control may vary across situations and actions, resulting in multiple perceptions of behavioral control depending on the situation (Ajzen, 1991).
Theory of Planned Behavior (Ajzen, 1991)
TPB and mHealth
TPB was successfully used for mHealth in preventing alcohol abuse (Kazemi et al., 2017), diabetes management (Samer & Al-Shami, 2020), dietary weight loss and physical activity (Salwen-Deremer et al., 2019), and coping with chronic diseases (Guido et al., 2018).