Theory of Planned Behavior

Imagine that your friend is trying to start exercising more regularly. According to the Theory of Planned Behavior (TPB), her decision to engage in this new routine is influenced by three key factors: attitude, subjective norms, and perceived behavioral control. 

Let’s first examine her attitude. Her new positive feelings toward exercise might stem from an article she read about how regular workouts will improve her physical health, boost her mood, and help her regulate hormonal fluctuations. Obviously, these all sound great, so she’s excited and highly motivated to start the new workout program. 

How about subjective norms—how will the environment affect her behavior? Your shared social circle has also likely played a significant role in her decision. Maybe a lot of your friends are fitness-focused—posting their achievements on Strava, going to yoga in the park, and joining run clubs. She might feel encouraged (or even slightly pressured) to join along, knowing that her friends will support her fitness journey and cheer her on as she pursues her athletic goals.

Lastly, let’s consider her perceived behavioral control. Your friend’s actual ability to start a new behavior (in this case, going to the gym) will also influence her decision. Luckily, she lives close to a gym, has a flexible work schedule, can easily afford a membership, and has plenty of friends who can offer up training advice. With all of this, she now feels confident that she can start incorporating regular exercise into her week!

The Theory of Planned Behavior would suggest that your friend’s positive attitude towards exercising, the social encouragement she receives from her environment, and her confidence in overcoming any logistical barriers all align to form her intention to start working out. This theory builds on the Theory of Reasoned Action (TRA) by adding the concept of perceived behavioral control, which addresses factors outside of the individual's control that might influence behavior.

The core component of the Theory of Planned Behavior (TPB)

Attitudes toward the Behavior 

This refers to the individual's positive or negative evaluations of performing a specific behavior. If a person believes that the behavior will lead to favorable outcomes, then they’re more likely to have a positive attitude towards it—contributing to their willingness. For example, if you think that cycling to the office will get you there faster than driving, then you might be more motivated to cycle. 

Subjective Norms

Subjective norms refer to the social pressure to perform or not perform a particular behavior. Our comportment is influenced by what we believe others expect of us, this can mean the perceived expectations of our friends, family, and society as a whole. For example, you may work in an office with a big cycle culture—with many coworkers using this as their main transport to get to work. The presence of social and cultural pressure may contribute to your inclination to follow suit.

Perceived Behavioral Control

Perceived behavioral control is a key component that distinguishes the Theory of Planned Behavior from the Theory of Reasoned Action. It refers to an individual’s perception of how easy or difficult it will be to perform a specific behavior, based on their past experiences, anticipated obstacles, and available resources.²

This concept encompasses both internal factors, like confidence in one's abilities, and external factors, such as the presence of barriers or facilitators. For example, if you’re deciding between cycling or driving to work you might be more inclined to cycle if you realize your car is out of gas or if there’s a major traffic jam, as these obstacles make driving seem more difficult.

Together, these components shape an individual's intention to perform a behavior, which is the antecedent to the actual implementation. The stronger the intention, the more likely the behavior will be performed, provided that the individual has adequate control over the behavior. Even if someone has a strong intention to perform a certain action, they must feel genuinely capable of overcoming any obstacles that might arise. For example, no matter how much your friend may want to take up running, if she trips and breaks her leg she will have to put off achieving this goal.