Theory of Planned Behavior

What is the Theory of Planned Behavior?

The theory of planned behavior (TPB) is a theory about the link between attitudes and behavior. It was proposed by Icek Ajzen (1980) as an extension of the theory of reasoned action.

Ajzen’s Theory of Planned Behavior (TPB) assumes that the best predictor of how we will behave is the strength of our intentions. According to TPB, the probability that individuals will exhibit behavior in harmony with an attitude they hold, depends on the strength of their behavioral intention, which is in turn influenced by three factors.

We’ll spend the remainder of this entry addressing these three critical factors.

1.   Attitude towards the behavior

Here we are talking about the attitude towards the behavior, not towards the object. For example, you might have a positive attitude about exercise, because you believe that it reduces tension. Exercise is the object of the attitude. But you might not like to sweat. And because you might not like to sweat, this attitude will make you lose interest in exercise.

TPB states that the attitude towards the behavior, which includes sweating, is a better predictor of your actions than your attitude about the exercise, because it affects your intentions.

2.   Subjective norms

The second factor, the subjective norms, refers to how you think your friends and family will evaluate your behavior. For example, you might think, ‘All my friends exercise, and they will think that it is appropriate that I do the same.’

In this case, you may exercise, despite your distaste for it, because your friends’ behavior defines exercise as the standard.

The relationship between the different aspects of this theory is shown in the Figure I, below.

diagram showing the theory of planned behavior
Figure I: The relationship between the different aspects of TPB

3.   Perceived behavioral control

The perceived behavioral control, the third factor, refers to a person’s belief that the behavior he or she is considering is easy or hard to accomplish. For example, a person will be more likely to engage in the health-related preventive behaviors, such as dental hygiene if he or she believes that it can be easily done.

In summary, the theory of planned behavior states that intention toward behavior, subjective norms, and perceived behavioral control, together shape an individual's behavioral intentions and behaviors.

The theory emphasizes that behavior follows from attitudes in a reasoned way. If a person thinks that a particular behavior associated with an attitude will lead to positive outcomes, that the other people would approve, and that the behavior can be exhibited readily, then the person will engage in the behavior.