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Theory of Reasoned Action/Theory of Planned Behavior

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by Holli Childs

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Definition and History of the Theory:

The Theory of Planned Behavior is a theory that uses beliefs and attitudes to predict an individual’s likelihood to engage in a certain behavior. It began as a simpler theory (the Theory of Reasoned Action), referring only behavioral and social beliefs that were the reasoning for individual actions in 1980, with psychologists Martin Fishbein and Icek Ajzen (1). It was originally called the theory of reasoned action. In 1985, Ajzen expanded on the theory to create the Theory of Planned Behavior by adding the perceived behavioral control and control beliefs constructs (2), as illustrated in Figure 1.

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Figure 1. The Theory of Planned Behavior.


The theory provides way to break down a public health problem to facilitate a population-based intervention. Each of the constructs provides an explanation of how a problem should be addressed in order to create the desired behavior change:


  • Behavioral Beliefs:  The probability that the behavior will lead to a certain outcome.
  • Attitude Toward the Behavior:  How positively or negatively the behavior is viewed.
  • Normative Beliefs:  The perceived expectations of close family, friends, or other influential relationships
  • Subjective Norm:  Perceived social pressure to either engage or not engage in the behavior.
  • Control Beliefs:  Perceived presence of factors that will either enhance or inhibit an individual’s ability to perform the behavior.
  • Perceived Behavioral Control:  Perceptions of an individual’s own capacity to perform the behavior.
  • Actual Behavioral Control:  The extent to which an individual has the necessary skills, resources, and other prerequisites in order to perform the desired behavior (3).

Each of these factors lead to an individual’s intention to perform the behavior, which then ultimately leads to the desired behavior.


Applications of the Theory

A perfect example of an intervention that addresses each of these constructs is Alcoholics Anonymous (AA) and other addiction recovery groups. Even though AA was formed before the model was proposed, it can still be applied. AA revolves around the desired behavior to stop drinking (4). Usually, an individual experiences something that makes them see the negative impact drinking has on their physical, emotional, or mental health. Sometimes on their own, and sometimes with the encouragement of family and friends, the individual joins AA (4). At that point, AA becomes a support group, influencing the normative and control beliefs of the individual by creating the social pressure to not engage in drinking. The stories of others create a positive attitude toward the behavior, and help enhance ones perception of their ability to ultimately quit drinking (4).


The theory of planned behavior has also been applied to condom use. With the implications of condom use in reducing the spread of HIV in many populations, it is very useful to apply the model to increase the beliefs and attitudes of the risk reduction that results from the use of condoms around the world to increase condom use and decrease HIV transmission (5-6). As a model for global health interventions, it can continue to be useful in any setting that is dependent on the behavior of individuals to create change.


Limitations to Using the Theory:

The theory of planned behavior does not consider economic and environmental influences on behavior (7). It is important to consider these factors before implementing or evaluating an intervention based on the model. For example, if condoms are not accessible to the population of interest, an intervention utilizing this model would be ineffective. It also assumes a linear decision making process that does not change over time (7). This assumes that the beliefs or social surroundings of the individual will never change. For example, if an intervention is based on influencing an individual’s decision whether or not to use condoms, if their perception of the risk changes over time, their beliefs around using condoms will also change. Because these changes occur, interventions may need to be modified and adapted to address the changing beliefs and surroundings of the individual and the population in which they reside.


Works Cited

(1) Ajzen I. TBP Diagram [Internet]. [cited 2015 Mar 13]. Available from: http://people.umass.edu/aizen/tpb.diag.html#null-link


(2) The Theory of Planned Behavior [Internet]. Behavioral Change Models. Available from: http://sphweb.bumc.bu.edu/otlt/MPH-Modules/SB/SB721-Models/SB721-Models3.html


(3) Value Based Management.net [Internet]. TPB Ajzen. 2014. Available from: http://www.valuebasedmanagement.net/methods_ajzen_theory_planned_behaviour.html

DRAFT: This module has unpublished changes.