Theories of reasoned action and planned behavior

We tend to say first of all we need to change their attitudes to change their behaviors. How far is it true?

This post delves into the researchers’ quest finding answers to this question.

In the 1960s, Fishbein and Ajzen reviewed published research and concluded the relationship between attitudes and behavior is not straightforward. They suggested the intention to perform the behavior determines whether to engage or not in a particular behavior.

Theory of Reasoned Action

That was the basis for their first theory: The Theory of Reasoned Action (TRA). They published it in 1967.

What it says is this; 

  • Our action depends on the intent of either doing it or not doing it.
  • Having an intent depends upon two determinants; not only the presence of a positive attitude towards the behavior but the presence of subjective norms (social pressure) matters too. 
  • A positive attitude includes two aspects: whether it is believed to be enjoyable or not enjoyable and beneficial or harmful.
  • The social pressure needs to be perceived; it may experience in two ways: telling by your significant other and seeing that they themselves are doing that.
  • Stronger the perceptions, the more likely stronger the intentions are.
A simplified form of the Theory of Reasoned Action in a diagram

Let us see how it applies in real life. 

Think that someone wants to carry out self-examination of the breast. She might do that if she has any intention of doing that. It is a fairly simple straightforward explanation.

What is challenging is to find out an explanation of how that intent is developed. According to the Theory of Reasoned Action, the intent depends on the presence of a favorable attitude towards that behavior and whether they feel any sort of social pressure (perceived social pressure) to engage in this behavior. Below, you can see its application in a nutshell.

Theory of Reasoned Action in action

Moreover, Wikipedia gives a very good account of the theory including its applications in communication, consumer behavior, and health behavior.

Theory of Planned Behavior

With time, Ajzen found the theory’s inadequacy in explaining some behaviors that are not under our control. As a result, he added another variable to the equation: perceived ability to perform the behavior as a determinant of the intent and re-named it as the “Theory of Planned Behavior”.

This theory is an extension of the theory of reasoned action. Both these are not exactly considered as behavior change theories but theories that help us to understand and predict the desired behavior. However, these two assist us in framing messages and developing health education materials too.

What it says: 

  • The third variable – perceived control over the performance of the behavior– was added to the previous theory. That is the only difference.  In the example below, if someone believes she has the ability to perform the task, she is more likely to engage in breast self-examination. It also includes the perceived ability to overcome barriers: economic, social, geographic, or even cultural.
  • The stronger the beliefs the stronger the intention of engaging in the behaviors are.
  • However, Ajzen in his seminal paper published in 1991cautions about the possible feedback effects of the behavior on the antecedent variables. (This is not shown in the diagram).
  • The perceived behavior control may have a direct influence on the behavior bypassing the intent of doing the behavior.
  • Although it is not shown in the diagram, attitudes towards the behavior, perceived social pressure, and perceived ability to engage in the behavior can influence each other according to the Ajzen’s 1991 paper.
Theory of Planned Behavior with an example

The following video clip explains the theory with an example.

Now, the most important question is this?

How can we use these theories for our benefit?

A review published in 1995 has concluded the efficiency of the theory varies depending on the type of behavior it was applied. They have found that two-third of the explained variation could be attributed to the intention of engaging in the desired behavior. This is a very important finding for us; in other words, most of our probability of engaging in a particular behavior depends on the degree of motivation. However, for addictive and screening behaviors, perceived behavioral control carried to have more control than the intention of doing the behavior.

Author: Prasantha De Silva

A specialist in Community Medicine board-certified in Sri Lanka and a research analyst in Canada

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