Theory of planned behavior
The theory of planned behavior is a psychological theory that links beliefs to behavior. The theory maintains that three core components, namely, attitude, subjective norms, and perceived behavioral control, together shape an individual's [|behavioral intentions]. In turn, a tenet of TPB is that behavioral intention is the most proximal determinant of human social behavior.
The theory was elaborated by Icek Ajzen for the purpose of improving the predictive power of the theory of reasoned action. Ajzen's idea was to include perceived behavioral control in TPB. Perceived behavior control was not a component of TRA. TPB has been applied to studies of the relations among beliefs, attitudes, behavioral intentions, and behaviors in various human domains. These domains include, but are not limited to, advertising, public relations, advertising campaigns, healthcare, sport management consumer/household finance, and sustainability.
History
Extension from the theory of reasoned action
Icek Ajzen proposed TPB in his chapter "From intentions to actions: A theory of planned behavior." TPB developed out of TRA, a theory first proposed in 1980 by Martin Fishbein and Ajzen. TRA was in turn grounded in various theories bearing on attitude and attitude change, including learning theories, expectancy-value theories, attribution theory, and consistency theories. According to TRA, if an individual evaluates a suggested behavior as positive, and if he or she believes significant others want the person to perform the behavior, the intention to perform the behavior will be greater and the individual will be more likely to perform the behavior. Attitudes and subjective norms are highly correlated with behavioral intention; behavioral intention is correlated with actual behavior.Research, however, shows that behavioral intention does not always lead to actual behavior. Because behavioral intention cannot be the exclusive determinant of behavior where an individual's control over the behavior is incomplete, Ajzen introduced TPB by adding to TRA the component "perceived behavioral control". In this way he extended TRA to better predict actual behavior.
Perceived behavioral control refers to the degree to which a person believes that he or she can perform a given behavior. Perceived behavioral control involves the perception of the individual's own ability to perform the behavior. In other words, perceived behavioral control is behavior- or goal-specific. That perception varies by environmental circumstances and the behavior involved. The theory of planned behavior suggests that people are much more likely to intend to enact certain behaviors when they feel that they can enact them successfully.
The theory has thus improved upon TRA.
Extension of self-efficacy
Along with attitudes and subjective norms, TPB adds the concept of perceived behavioral control, which grew out of self-efficacy theory. Bandura proposed self-efficacy construct in 1977, in connection to social cognitive theory. Self-efficacy refers to a person's expectation or confidence that he or she can master a behavior or accomplish a goal; an individual has different levels of self-efficacy depending on the behavior or intent. Bandura distinguished two distinct types of goal-related expectations: self-efficacy and outcome expectancy. He defined self-efficacy as the conviction that one can successfully execute the behavior required to produce the outcome in question. Outcome expectancy refers to a person's estimation that a given behavior will lead to certain outcomes. Bandura advanced the view that self-efficacy is the most important precondition for behavioral change, since it is key to the initiation of coping behavior.Previous investigations have shown that a person's behavior is strongly influenced by the individual's confidence in his or her ability to perform that behavior. As self-efficacy contributes to explanations of various relationships among beliefs, attitudes, intentions, and behavior, TPB has been widely applied in health-related fields such as helping preadolescents to engage in more physical activity, thereby improving their mental health, and getting adults to exercise more.
Key concepts
Normative beliefs and subjective norms
- Normative belief: an individual's perception of social normative pressures, or the beliefs of relevant others bearing on what behaviors should or should not be performed.
- Subjective norm: an individual's perception about the particular behavior, which is influenced by the judgment of significant others.
Control beliefs and perceived behavioral control
- Control beliefs: an individual's beliefs about the presence of factors that may facilitate or hinder performance of the behavior.
- Perceived behavioral control: an individual's perceived ease or difficulty of performing the particular behavior. The concept of perceived behavioral control is conceptually related to self-efficacy. It is assumed that perceived behavioral control is determined by the total set of accessible control beliefs.
Behavioral intention and behavior
- Behavioral intention: an individual's readiness to perform a given behavior. It is assumed to be an immediate antecedent of behavior. It is based on attitude toward the behavior, subjective norm, and perceived behavioral control, with each predictor weighted for its importance in relation to the behavior and population of interest.
- Behavior: an individual's observable response in a given situation with respect to a given target. Ajzen advanced the view that a behavior is a function of compatible intentions and perceptions of behavioral control. Perceived behavioral control is expected to moderate the effect of intention on behavior, such that a favorable intention produces the behavior only when perceived behavioral control is strong.
Conceptual / operational comparison
Perceived behavioral control vs. self-efficacy
Ajzen wrote that the role of perceived behavioral control in the theory of planned behavior derived from Bandura's concept of self-efficacy. More recently, Fishbein and Cappella advanced the view that self-efficacy is equivalent to perceived behavioral control in Ajzen's integrative model. Perceived behavioral control can be assessed with the help of items from a self-efficacy scale.In previous studies, the construction of measures of perceived behavioral control has had to be tailored to each particular health-related behavior. For example, for smoking, an item could read "I don't think I am addicted because I can really just not smoke and not crave for it" or "It would be really easy for me to quit."
The concept of self-efficacy is rooted in Bandura's social cognitive theory. It refers to the conviction that one can successfully execute the behavior required to attain a desired goal. The concept of self-efficacy is used as perceived behavioral control, which means the perception of the ease or difficulty of the particular behavior. It is linked to control beliefs, which refer to beliefs about the presence of factors that may facilitate or impede performance of the behavior.
Perceived behavioral control is usually measured with self-report instruments comprising items that begin with the stem, "I am sure I can...." Such instruments attempt to measure the individual's confidence that he or she can execute a given behavior.
Attitude toward behavior vs. outcome expectancy
The theory of planned behavior specifies the nature of the relationship between beliefs and attitudes. According to the theory, an individual's evaluation of, or attitude toward, a behavior is determined by his or her accessible beliefs about the behavior. The term belief in this theory refers to the subjective probability that the behavior will produce a certain outcome. Specifically, the evaluation of each outcome contributes to the attitude commensurately with the person's subjective probability that the behavior produces the outcome in question. A belief is accessible if available from long-term memory.The concept of outcome expectancy originated in the expectancy-value model. Outcome expectancy can be a belief, attitude, opinion, or expectation. According to the theory of planned behavior, an individual's positive evaluation of his or her performance of a particular behavior is similar to the concept of perceived benefits. A positive evaluation refers to a belief regarding the effectiveness of the proposed behavior in reducing the vulnerability to negative outcomes. By contrast, a negative self-evaluation refers to a belief regarding adverse consequences that can result from the enactment of the behavior.
Social influence
The concept of social influence has been assessed in both the theory of reasoned action and theory of planned behavior. Individuals' elaborative thoughts on subjective norms are perceptions of whether they are expected by their friends, their family, and society in general to perform a particular behavior. Social influence is measured by evaluating the attitudes of social groups. For example, in the case of smoking:- Subjective norms the individual attaches to the peer group include thoughts such as, "Most of my friends smoke" or "I feel ashamed of smoking in front of a group of friends who don't smoke";
- Subjective norms the individual attaches to the family include thoughts such as, "All of my family smokes, and it seems natural to start smoking" or "My parents were really mad at me when I started smoking"; and
- Subjective norms the individual attaches to society or the general culture include thoughts such as, "Everyone is against smoking" or "We just assume everyone is a nonsmoker."