Icek Ajzen’s Theory of Planned Behavior Explained


The theory of planned behavior links the beliefs of an individual to their behavior. It is an idea that was first proposed by Icek Ajzen, allowing for the predictability of reasoned actions when behavioral controls are in place. It is an idea that can be applied to any human interactions, from marketing campaigns to healthcare to religion.

First proposed in 1980 and the revised in 1985, Ajzen suggests that there is a 3-step process which people take to plan their behaviors.

1. An action is evaluated to determine if the behavior would be seen as positive.
2. There is an evaluation to determine if there is a significant group of other people who would want to have the behavior performed.
3. The higher intention or motivation of the behavior is evaluated to determine if a positive personal outcome can be achieved.

When there are positive responses in all three steps, then a person is more likely to decide to go through with their planned behavior. If a negative response is received, however, a person is more likely to decide to not go through with that behavior.

Adding the Concept of Perceived Behavioral Control

Newton’s Third Law of Motion states this: “For every action, there is an equal and opposite reaction.” Under the concept of perceived behavioral control, it would be more accurate to say that for every action, there is a planned and anticipated response which will occur.

Each person has certain expectations about behaviors that come from their upbringing, experiences, and personality.

These expectations can include the motivation behind a planned behavior, the performance of the behavior, or the feelings which initiate the decision to consider the behavior in the first place. People can expect either success or failure based on the planned behaviors that they are considering. Repetitive outcomes can enhance the expectations of success or failure, as well as the emotions which come with either outcome.

Outcome expectations can be separated into two categories: outcome expectancies and self-efficacy.

An outcome expectancy is the term given to the estimation that a specific planned behavior will lead to a certain conclusion. Self-efficacy is the conviction that a person has about themselves and their ability to produce such a conclusion. When combine, a definition of success for the planned behavior is obtained. Then, based on an ability to meet that definition, a person will either experience the thrill of victory or the agony of defeat.

Key Variables in the Theory of Planned Behavior

Ajzen recognized that people have two types of beliefs: normative and subjective. Normative beliefs are those that are independently developed and help to define a personal moral code. Subjective beliefs are the perceptions that can be influenced by the judgments or observations that others may provide.

Within each belief system, there are control beliefs and perceived behavioral controls. Control beliefs look at the factors which make it possible or impossible to perform a planned behavior. The presence of these factors may be real, perceived, or imaginary, but will still impact the final decision that an individual makes. Perceived behavioral controls are the individual’s observations about how easy or difficult it is to manipulate the factors which help or hurt the decision to pursue a planned behavior.

Then individuals have a final step: they can either intend to perform the behavior or they can response to the stimuli in their environment and perform the behavior. The intention to perform a planned behavior is an evaluation of a person’s readiness. Some people may never follow through with a planned behavior because the stimuli around them is more negative than positive. Others may be triggered by a small encouragement because they have perceived the stimuli to be more positive than negative.

How Social Influence Creates Planned Behaviors

Ajzen notes that people have two different attitudes toward behavior. One is based on a definition of behavior they give to it that comes from their own belief systems. A person might look at drinking alcohol as a “bad” behavior because their father is an alcoholic and is never home. Based on this definition, an individual’s planned behavior would be to never drink because they don’t want to be like their father.

The other definition of comes from the perspectives of an individual’s social groups and networks. A peer group might look at drinking alcoholic beverages as “fun.” That group might get together every weekend to have a party which includes alcohol. An invitation to join them and partake in drinking would be considered “good” because it would add definition to the social norms and expectations which also influence the individual.

In general terms, Ajzen notes that there are three specific influences that can affect the decision to act upon a specific definition of a planned behavior.

1. Subjective Social Group Norms.
If being part of a group which believes drinking alcohol is “normal” and “fun,” then an individual is more likely to participate in this behavior. If the group believes that drinking alcohol is “bad” and should be avoided, then they are more likely to participate in the planned behavior of avoidance instead.

2. Subjective Family Group Norms.
The family environment also encourages specific behaviors. If everyone in a family drinks alcohol occasionally, then it will seem natural to the individual to begin drinking. If the expectation is to avoid alcohol and there is a negative response to anyone who does drink, then an individual will be less likely to consume an alcoholic beverage.

3. Subjective Societal Norms.
Societies and cultures have certain expectations that are considered “good” and “bad.” If a person looks at alcoholic beverages and says, “Everyone is against drinking alcohol before the age of 21,” or assumes that anyone below the age of 21 isn’t drinking, then that individual will be less likely to drink. If society encourages the behavior, that individual is more likely to participate in that planned behavior.

These influences weigh on the decision that an individual must make. They must also look at their own personal belief systems and structures to determine if there is a benefit to the planned behavior. Each influence is weighed in importance and assigned either a positive or negative value. Then a final decision is made. If the value is on the positive side, the planned behavior will likely take place.

If the value is on the negative side, then the planned behavior will not likely take place.

Why Do Some People Choose Negative Values Over Positive Values?

Sometimes, it seems like people choose a negative value over a positive value. You might see a husband decide to start an affair or you might see a teen decide to start smoking. From your perspective, you see these as negative choices. The husband is clearly risking his marriage and the teen is clearly risking their health. Why would they choose something that has a negative value?In the theory of planned behavior, the individual’s evaluation of value is what makes up the core of planned behaviors. Society, family, and social groups might all tell a husband that cheating on a spouse is a bad decision or tell a teen that smoking is bad for their health. The individual perspective, however, might see the thrill of an affair has having more value, just like being accepted into a social group might have more value to the teen.

Even for people who choose a planned behavior that ends up being negative, there is generally an evaluation that there is a positive result will be achieved. A person might know that suicide has negative outcomes, but the value of not needing to deal with the issues of life has more value to them at the time of action – despite their knowledge that a negative outcome for others will be the result.

Beliefs and evaluations are sometimes the result of cognitive processing: “I want to feel alive again, so I’m going to have an affair.” Sometimes it is the result of environmental conditioning. “My father had an affair, so I’m a cheater too.” And sometimes it is the result of a thinking error. “I can love my spouse more because I’m in love with someone else.”

Emotions can sometimes come into play with the decision of a planned behavior as well. This is not a drawback to the predictability of a planned behavior. It is simply a reflection of the human condition.

It is true that emotions can make it seem like a planned behavior is “surprising” to others. A conservative minister decides to have an affair and people are shocked, but if a supervisor at the bowling alley makes the same decision, there is less shock value. Why? Because we make assumptions based on the various structures that we see in the lives of others. We make predictions about behaviors from our own evaluations of those structures instead of looking at the person.

Icek Ajzen’s theory of planned behavior is one example of how people look at decisions before they act. It is a way to determine how likely we each are to make positive or negative choices, as well as how likely others are to make a similar choice.