SLTinfo logo

Theory of Planned Behavior

Explaining behavior

A useful social psychological model that can be used to assist our thinking when considering why people perform particular behaviors (e.g. an adult attending a speech therapy assessment, a parent taking the time to attend a meeting with a class teacher; a Head of Department implementing a policy change) is the Theory of Planned Behavior (Ajzen, 1985; Ajzen and Madden, 1986; Schifter and Ajzen, 1985). This model has been around for a long time now and, like most models, it is not without its critics. However, it does provide a useful framework, that sits nicely within the systems approach, for considering why people perform the behaviors they do. Figure 1 sets out a simplified model in diagrammatic form.

Theory of Planned Behavior

Figure 1. Simplified Theory of Planned Behavior (source: Ajzen, 1988)

Figure 1 indicates that a person’s intentions are a good predictor of their behavior. The stronger the intention to perform a particular behavior, the more likely the person is to perform that behavior. This, however, is not especially illuminating – to say that people do what they intend to do is not particularly instructive. We need to consider the determinants of behavioral intentions. We see from Figure 1 that intentions are a function of three determinants:

  1. beliefs
  2. salient referents
  3. perceived behavioral control

Behavioral beliefs

Behavioral beliefs link the behavior to certain outcomes. For example, a person may believe that reducing the amount of salt in their diet (the behavior) leads to a reduction in blood pressure and severely restricts the range of approved foods (the outcomes). Thus, the attitude towards the behavior is determined by the person’s evaluation of the outcomes associated with the behavior. The more positively the person evaluates the outcomes and believes that the behavior will achieve these outcomes then the more likely it is that the person will perform the behavior.

Salient referents

Salient referents are individuals or groups that the person believes will approve or disapprove of him or her performing the behavior. The important referents often include the person’s parents, spouse, partner, close friend, co-workers and, in some cases, people such as their doctor, accountant, and so on. As Ajzen (1988:121) explains: “Generally speaking, people who believe that most referents with whom they are motivated to comply think they should perform the behavior will perceive social pressure to do so.” The converse would also hold true, i.e. if I believe that most people with whom I am motivated to comply would disapprove of the behavior then I will perceive social pressure not to perform the behavior.

Perceived behavioral control

This refers to the perceived ease or difficulty of performing the behavior. The greater a person’s perceived behavioral control, the stronger should be their intention to perform the behavior. So, for example, if I consider that I have the necessary resources (e.g. time, means of transport) to attend a meeting with a class teacher then I am more likely to form an intention to perform the behavior…of meeting with the class teacher.

We see then that the three determinants of behavioral beliefs, salient referents and perceived behavioral control each contribute to the strength of a person’s intention to perform a behavior.

Of course, just because a person forms an intention to perform a behavior this does not invariably mean that the person will actually perform the behavior. For example, I may form the intention to meet with the class teacher but my car may unexpectedly get a punctured tire which prevents me traveling to the meeting. Also, the length of time that passes between forming the intention to perform the behavior and the actual time when the behavior is to be performed is potentially influential. If the duration between intention and timing of the behavior is short then it is more likely that the behavior will be performed. However, if the duration is long (perhaps several days or even weeks) then other factors may intervene that cause the person to reconsider and reshape their attitude towards the behavior. For example, a new revelation about a politician’s backhand dealings may cause me to adopt a different set of beliefs about that politician’s ability to realize the outcomes that are important to me and I may choose to vote (the behavior) for a different candidate, or not at all. Similarly, if I have an argument with my spouse this may reduce my desire to comply with their wishes and this may again influence my intention to perform a particular behavior for which I had earlier evaluated my spouse’s approval as important or necessary.


Imagine that you are a teacher in a local School who has conducted a SWOT Analysis of parent-partnership practices within the school. You have decided to hold an Open Event (coffee morning) in order to meet informally with the parents of children in your care, as a means of getting to know the parents and their hopes for their child’s educational success.

  1. Try to identify your beliefs about this particular action/behavior in terms of outcomes, e.g. holding a  coffee morning…

                    is a good way to meet parents

                    is a waste of time, as no one will attend

                    is time-consuming but it will pay off later

  1. Identify any salient referents with whom you feel motivated to comply, e.g. would you perceive any social pressure from the…

                    Head Teacher?

                    Head of Section?


                    children/young people?

                    Local Authority officers?

                    Government inspectors?

  1. How would you rate your perceived behavioral control?

                    Would you have complete control over setting up and implementing a coffee morning?
How easy is it for you to set up and run a coffee morning?
Do you have enough cups and saucers?

The more positively you have weighted the above three determinants then the stronger should be your intention to perform the behavior/hold a coffee morning.

  1. Now think of another behavior (e.g. implementing a particular policy across the whole school, participating in a twilight session, attending an LEA meeting) and see if you can apply the above model.

  2. Finally, think of a behavior that you expected another person to perform (e.g. a parent attending a meeting with you, the Head teacher following through on a promise to purchase a new desk for your classroom) but that they did not carry out. Using the Theory of Planned Behavior, see if you can pinpoint which determinants most affected this non-performance.


Ajzen, I. (1985) ‘From intentions to actions: a theory of planned behavior’ in Kuhl, J. and Beckmann, J. (eds) Action-control: From Cognition to Behavior Heidelberg: Springer.

Ajzen, I. (1988) Attitudes, Personality and Behavior Buckingham: Open University Press.

Ajzen, I. and Madden, T.J. (1986) ‘Prediction of goal-directed behavior: attitudes, intentions and perceived behavioral control’ Journal of Experimental Social Psychology 22, 453-474.

Schifter, D.B. and Ajzen, I. (1985) ‘Intention, perceived control, and weight loss: an application of the theory of planned behavior’ Journal of Personality and Social Psychology 49, 843-851.