Theory of Planned Behavior

The theory of reasoned action and theory of planned behavior have been influential cognitive models for understanding and predicting social behavior across a variety of domains. Both focus on the question of how to determine the likelihood that an individual will engage in a specific behavior. The theory of reasoned action exam-ines determinants of volitional behavior, or behavior that falls under a person’s individual control, whereas the theory of planned behavior provides an extension of the previous model to examine determinants of behavior over which individuals do not exert complete control. The theory of reasoned action and theory of planned behavior arose in response to discrepant findings in the social psychological literature regarding the relationship between attitudes and behavior. During this time, contrary to the common assumption of attitudes guiding behavior, there was increasing evidence that people’s attitudes did not in fact predict their actions. The theories of reasoned action and planned behavior attempted to reconcile these findings by examining additional deter-minants of behavior and identifying specific conditions under which attitudes would guide behavior.

Theory of Reasoned Action

The theory of reasoned action was developed by Martin Fishbein and Icek Ajzen with the aim of identifying determinants of behavioral decisions that are volitional, or under an individual’s control. The theory posits that attitudes, subjective norms, and intentions combine to determine the likelihood of an individual performing a specific action.

Attitudes are the evaluative beliefs surrounding the target behavior (i.e., Does one feel positively or negatively toward engaging in this behavior?). They are based on behavior beliefs, which are beliefs about the outcomes associated with doing a behavior. Additionally, attitudes are determined by the person’s evaluations of the outcomes. Therefore, a positive attitude toward a behavior will occur when a person believes that a behavior results in a positive outcome and that outcome is one that is valued by the individual.

Subjective norms are perceived social pressure to perform a behavior. They are based on normative beliefs, which are beliefs about whether important others approve or disapprove of one engaging in a particular behavior. Additionally, the strength of the subjective norms is determined by how motivated a person is to comply with other people’s wishes. Thus, for subjective norms to be strong, an individual must not only believe that others approve of him or her engaging in a behavior but must also consider it important to comply with the wishes of others.

In this model, it is suggested that rather than having a direct influence on behavior, attitudes and subjective norms will influence behavior indirectly, through their impact on intentions, people’s motivations or willingness to engage in a particular action. Intentions are identified as the most immediate antecedent of behavior. If intentions to engage in a behavior are strong, it is more likely that an individual will actually perform the behavior; conversely, if intentions are weak, it is less likely that one will engage in the specified behavior.

In sum, the theory of reasoned action suggests a general sequence in which attitudes and subjective norms jointly determine behavioral intentions, which then determine actual behavior. If attitudes toward a behavior are favorable, an individual will have stronger intentions, consequently resulting in greater likelihood of engaging in the behavior. On the other hand, if attitudes are unfavorable, individuals will have weaker intentions to engage in the behavior and will therefore be less likely to carry out the behavior. Similarly, if subjective norms are high (others indicate approval of the behavior and one is motivated to comply with their wishes), an individual will express stronger intentions and will consequently be more likely to actually engage in the behavior; if subjective norms are low (others disapprove of the behavior and/or one does not care about complying with others’ wishes), an individual will have weaker intentions and be less likely to perform the behavior.

Application of the Theory of Reasoned Action

To provide an example, the theory of reasoned action could be used in an organizational setting to predict whether workers in a high-risk occupation will follow workplace safety regulations. The theory predicts that attitudes toward the safety regulations (beliefs about whether following these regulations is good or bad) and subjective norms toward the regulations (beliefs about whether important others would want one to follow the regulations) will both determine a worker’s intentions to engage in these safe behaviors in the workplace. For instance, if people believe that following regulations at work will keep them safe, and they value this outcome, they will have a positive attitude toward engaging in safe workplace behaviors. Further, if they believe that it is important to their families and coworkers that they engage in these safe behaviors, and they want to comply with the wishes of these important others, they will have strong subjective norms surrounding the behavior. These positive attitudes and subjective norms will then translate into intentions, or motivation and willingness to follow the safety regulations, which will then determine actual behavior.

Limitations of the Theory of Reasoned Action

One important limitation of the theory of reasoned action is that it does not consider impeding or facilitating factors that might influence one’s ability to engage in a behavior. The theory assumes that if a person is motivated to engage in a behavior, that particular action will be carried out. However, many behaviors require certain skills, resources, opportunities, or the cooperation of others to be carried out. For instance, individuals who are employed in high-risk jobs might have positive attitudes and subjective norms with regard to workplace safety (i.e., they are motivated to engage in behaviors that will keep them safe in the workplace); however, there may be external constraints, such as lack of funding, understaffing, or limited safety equipment, that exert a strong influence on their ability to carry out specific safety behaviors. Although the presence or absence of such factors should influence how easy or difficult it is for individuals to carry out behavior, the impact of these factors on behavior is not examined in the theory of reasoned action.

The Theory of Planned Behavior

The theory of planned behavior was developed by Ajzen as an extension of the theory of reasoned action to examine factors outside of one’s control that might also exert influence on intentions and behaviors. Specifically, the theory of planned behavior asserts that if a behavior is less volitional in nature, it is important to consider the degree to which various factors either impede or facilitate an individual’s ability to engage in that behavior. This determinant of behavior is referred to as perceived control, and it is examined in addition to the attitude, subjective norm, and intention components included in the theory of reasoned action. Perceived control is based on an individual’s perceptions of how likely facilitating or constraining factors are to occur and to what degree these factors will influence the ease or difficulty of engaging in the behavior. Greater perceptions of perceived control lead to stronger intentions, resulting in greater likelihood of actually engaging in the behavior; less perceived control leads to weaker intentions and a lower likelihood of engaging in the behavior. Moreover, unlike attitudes and subjective norms, which are proposed to influence behavior only indirectly through their influence on intentions, perceived control is thought to exert a direct influence on behavior, as well as an indirect influence through its impact on intentions.

In summary, the theory of planned behavior asserts that attitudes, subjective norms, and perceived control will combine to influence intentions, which will then determine behavior. The theory of planned behavior differs from the theory of reasoned action, in that it examines the role of perceived control and therefore applies to a wider array of behaviors that are not fully under an individual’s control. Additionally, in this model both intentions and perceived control exert a direct influence on behavior.

Predicting and Explaining Behavior

The theories of reasoned action and planned behavior have generated a large magnitude of research, the majority of which has focused on the prediction and explanation of behavior. Typically, researchers have measured attitudes, subjective norms, and perceived control in relation to a specific behavior and then used these constructs to either explain existing intentions and behavior or predict future intentions and behavior. Meta-analyses indicate that the theories of reasoned action and planned behavior constructs account for up to 40% of the variance in behavior and intentions. Moreover, inclusion of the perceived control construct accounts for significant variance beyond that accounted for by attitudes and subjective norms. Of these constructs, subjective norms appear to be the weakest predictor of intentions and behavior.

The theories of reasoned action and planned behavior have predicted behavior across many domains. In the context of the workplace, these theories have been applied to explain and predict behavior related to diversity training, workplace technology, occupational safety and health, occupational deviance, and career decision making. Although the primary body of research generated by these theories has focused on predicting and explaining existing behavior, more recent work has applied these models to develop interventions designed to modify behavior.


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