What is the main difference between the theory of reasoned action and the theory of planned Behaviour?

By Charlotte Nickerson, published June 15, 2022 | Fact Checked by Saul Mcleod, PhD

The Theory of Reasoned Action, often considered in tandem with the Theory of Planned Behavior, is a cognitive theory and mathematical model that helps psychologists understand human behavior in specific contexts, such as whether or not people will take up healthy habits.

Key Takeaways

• The theory of reasoned action is a mathematical model that allows scientists to predict behavioral intentions as a function of attitudes and subjective norms.
• The theory of reasoned action was first proposed by the psychologists' Martin Fishbein and Icek Ajzen as an improvement of the information integration theory, another model of human behavior.
• The three most important components of the theory of reasoned action are beliefs, attitudes, and intentions.
• Beliefs usually describe the probability that a person thinks some action will cause a certain outcome; attitudes concern whether or not someone thinks that outcome is favorable or unfavorable; and intention, the way that someone intends to behave in response to beliefs and attitudes.
• Fishbein and Ajzen proposed a hierarchy for the theory of reasoned action. They believed that attitude, subjective norms, and perceived behavior control all contribute to intention, which leads to some extent to behavior. The behavioral, normative, and control beliefs underlying these are influenced by external variables such as demographics and personality.
• Another improvement that Fishbein and Ajzen (1975) made to the theory of reasoned action is the inclusion of two new elements in predicting behavioral intent: attitude, and the expectations of other people.

Theoretical Origins

The Theory of Reasoned Action, which is often extended to the Theory of Planned Behavior, is a cognitive theory that helps psychologists understand human behavior in specific contexts.

Most notably, the Theory of Reasoned Action has been used to assist in predicting and explaining several health behaviors (LaCaille, 2020).

The theory of reasoned action was developed by the psychologists Martin Fishbein and Icek Ajzen in 1975, originally as an improvement to the information integration theory.

Fishbein and Ajzen formulated the theory after attempting to determine the differences between attitude and behavior. The theory of reasoned action differs from information integration theory for a few reasons. The first of these is the idea of behavioral attention.

Additionally, the theory of reasoned action acknowledges that there are factors that can limit the influence of attitude on behavior.

The Theory of Reasoned Action has four main terms: Belief, Attitude, Subjective Norms, and Intention (Fishbein and Ajzen, 1975):

Subjective norms are the sum of all of the important people in someone's life and whether they think those people would want them to perform the behavior.

For example, someone may think of whether their spouse, doctor, or mother wants them to exercise. All in all, intentions are a function of attitude and subjective norms.

Psychologists define two types of subjective norms: injunctive norms, and descriptive norms. Injunctive norms describe what people think other people think they should do.

Someone who feels an injunction to carry out an action, such as eating acai bowls, does so because they think other people think that they should eat them.

Descriptive norms, meanwhile, are someone's perception of what other people think they should do, though the truth may be different.

For example, consider someone thinking about whether or not to wear a surgical mask. Their injunctive norm may be that they believe that most experts want them to wear a mask, as do their doctors and family members.

However, a descriptive norm describes someone's belief about what other people actually do.

If someone believes that not many people wear masks, the descriptive norm that few people wear masks influences their decision about whether they should do so.

Subjective norms are a function of the normative beliefs of a society, and the motivation for someone to comply across each important person in someone's life.

These important others can include, say, someone's friends, partner, children, parents, and personal trainer. Each of these people have two psychological values (Fishbein and Ajzen, 1975):

1. Normative Belief (NB): Whether or not someone believes that the other wants them to carry out an action.

   For example, whether or not someone thinks their doctor wants them to exercise. These beliefs can have different strengths; a -3, for example, could mean that someone believes their doctor is certain that they do not want them to exercise, while a +3 could mean that they are certain that their significant other wants them to exercise.

2. Motivation to Comply (MC): Motivation to comply describes how much someone wants to do what the significant other wants them to do.

   For example, someone may have a tendency to not want to do what their mother wants them to do, or to do what their children want them to do. Like Normative Belief, Motivation to Comply can have different levels of strength.

Each of these terms are often treated by behavioral scientists as factors in an equation intended to predict human behavior. As such, they are all related — factors that ultimately contribute to behavior.

Fishbein and Ajzen (1975), who originated the theory of reasoned action, created a diagram to describe the relationship between the main components of their model.

Attitudes, norms, and perceived control each lead to intentions — the readiness to do a behavior. These intentions can then lead, albeit imperfectly, to behaviors.

After Fishbein and Ajzen's (1975) original behaviors, other scientists have attempted to better group and explain the  background factors that lead to the behavioral, normative, and control beliefs that lead to attitude, subjective norms, and perceived behavioral control, respectively. These environmental factors could include:

• Personal factors: traits, locus of control, emotions, and health concerns.
• Demographic factors: Age, gender, race, ethnicity, education, income, and religion.
• Environmental factors: diagnosis, stress, and media exposure.

Neighbors, Foster, and Fossos (2013) outlined several models of addiction. One of these was based on the Theory of Reasoned Action and its predecessor, the theory of Planned Behavior.

Neighbors, Foster, and Fossos argued that the construct of social norms is similar to the idea of injunctive norms put forth by other social norms.

As the psychologists explain it, if an adolescent believes that the important people in their life would disapprove if they smoked cigarettes, they should be less likely to intend to smoke cigarettes — and, subsequently, less likely to actually smoke cigarettes.

These subjective norms are distinct from the social norms that other theories put forth in two ways.

Firstly, they focus exclusively on the important others in someone's life as a reference group, and the behavior that is relevant to the theory is that of the perceiver, rather than behavior in general.

The question that the theory of reasoned action asks is not about the extent to which someone thinks the others that they care for approve or disapprove of smoking, but rather the extent to which someone thinks others approve or disapprove of their smoking and particular (Neighbors, Foster, and Fossos, 2013).

Although this may seem like a small distinction, there are cases where it is an important one.

For instance, as Neighbors, Foster, and Fossos (2013) note, parents who have moderate or favorable views on the legalization of marijuana may be less approving of marijuana use by their own daughter.

One of the most popular applications of the theory of reasoned action is to assess the probability that a group of people will follow a particular health behavior.

One study attempts to see if the theory of reasoned action would increase breakfast consumption among students in a secondary school in Iran (Hosseini et al., 2015).

To do so, the researchers implemented an informational program that intended to promote breakfast consumption.

Students then filled out a questionnaire before and after the intervention. The first part of this questionnaire concerned knowledge about breakfast consumption, and the second, components of the Theory of Reasoned Action's factors.

According to the data, subjective norms — whether or not someone believed others around them were consuming breakfast, and whether or not they thought the important others in their life wanted them to consume breakfast — were the best predictors of breakfast consumption (Hosseini et al., 2015).

Marketers have also used the theory of reasoned action to describe a wide variety of behaviors, such as the consumption of automobiles, banking services, computer software, coupons, detergents, and soft drinks.

The researchers Richard P. Bagozzi, Nancy Wong, Shuzo Abe, and Massimo Bergami sought to understand the theory in the context of different cultures by looking at fast food consumption in the United States, Italy, China, and Japan.

They found that predictions under the theory of reasoned action tended to vary based on the social setting — whether someone is eating alone or with others — and cultural orientation — whether someone lives in an individualistic or collectivist culture.

The researchers found that subjective norms tended to influence decisions when eating with friends, but not alone, regardless of the level of individualism or collectivism in one's culture.

However, the impact of attitudes, subjective norms, and past behavior on intentions were greater for Americans than Italians, or Chinese or Japanese people.

In general, there was more explainable variance in behavior for western than eastern cultures (Bagozzi, Wong, Abe, & Bergami, 2000)

Limitations

The theory of reasoned action has some limitations. One of these is a significant risk of confounding between attitudes and norms. This happens because attitudes can often be reframed as norms, and norms as attitudes.

For example, someone who has the attitude that kale is good for them may simply be reflecting a subjective norm of a group of influential friends, family, doctors, and social media influencers who believe that kale is healthy.

There are also practical constraints to the theory of planned behavior, such as the limited ability and time of researchers to accurately measure factors that contribute to the models in the theory, as well as environmental or organizational limits and unconscious habits that limit someone's freedom to act.

The theory of planned behavior attempts to resolve these limitations through the idea of perceived behavior control (LaCaille, 2020).

Theory of Reasoned Action vs. Theory of Planned Behavior

The theory of planned behavior is essentially a more current version of the theory of reasoned action.

The most important difference between the two is the idea of perceived behavior control — the belief that someone is actually capable of doing a behavior in question, such as exercising or eating healthier.

In the mathematical version of the theory of planned behavior, perceived behavior is a function of control beliefs — beliefs about whether certain factors will be an obstacle — and power of control factors — which is a measure of how powerful a factor is in either stopping someone from doing a behavior or enabling them to do so (Rossi & Armstrong, 1999).

Charlotte Nickerson is a member of the Class of 2024 at Harvard University. Coming from a research background in biology and archeology, Charlotte currently studies how digital and physical space shapes human beliefs, norms, and behaviors and how this can be used to create businesses with greater social impact.

Content is rigorously reviewed by a team of qualified and experienced fact checkers. Fact checkers review articles for factual accuracy, relevance, and timeliness. We rely on the most current and reputable sources, which are cited in the text and listed at the bottom of each article. Content is fact checked after it has been edited and before publication.

Nickerson, C. (2022, June 15). Theory of Reasoned Action . Simply Psychology. www.simplypsychology.org/theory-of-reasoned-action .html

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