Have you ever wondered what makes human beings react in the way they do? Imagine how powerful you would become if you had the ability to accurately predict how people would react in different scenarios.

With this ability, you would most likely end up a rich car salesman who knows just what to say and do to make customers buy.

Human beings are curious by nature and we will always have a tendency to look for the reason behind why people act the way they do. When your set foot into a car yard looking to buy a car, you are bombarded with a number of options. Sometimes, you might even find two closely similar cars on display. After all has been said and done, you will only pick one car.

The same is true about work assignments. When you are given a task, you will usually have different possible approaches that you can take. However, you will only end up picking one approach.

What could have motivated you to react to the stimulus in the way you did? What could have driven you to choose a specific car from dozens of cars in the yard? What influenced your decision-making process that you went through to arrive at a final decision?

Certainly, one of the most difficult things to get a firm and full handle on is human behavior. It certainly doesn’t help that individuals are unique in their own ways, and that they cannot be boxed in categories especially when it comes to behavior. Not all people react in the same way, or behave in the same manner, even under the exact same circumstances. There are various factors at play, and these are what psychologists and thinkers have been trying to study and make sense of in the past few decades.

Studies on human behavior have resulted in a multitude of theories and assumptions, with psychologists and researchers postulating this or that. Some of them make sense, others made enough of an impact to still be considered valid today, and there are others that have already been generally accepted as fact.

In this discussion, we will take a look at one of these assumptions, known as the Theory of Planned Behavior, or TPB.


Before we can fully proceed to understanding the Theory of Planned Behavior, it is important to retrace the earlier steps that led to its development. There were several earlier theories that contributed to the development of the TPB, and the two most recognizable ones were the Information Integration Theory and the Theory of Reasoned Action.

The Information Integration Theory

After a series of experiments, Norman Anderson first introduced the Information Integration Theory in 1971. In his theory, Anderson tried to explore and describe how the mixing or combination (integration) of new information with existing thoughts or cognitions results in the formation and/or changes in one’s attitudes. In short, before an individual can make a final or overall judgment, he will still undergo a process of integrating information, derived from various sources, in aid of arriving at that judgment.

Anderson’s theory holds that a persuasive message is composed of ideas, which are relevant pieces or bits of information, with each bit defined by two qualities:

  • Value, or the favorable or unfavorable evaluation of the bit of information
  • Weight, or the perceived importance of the bit of information

This is described further in the proposed three functions in the integration process:

  1. Valuation, or setting value and weight on the information derived from various sources, with respect to multiple stimuli;
  2. Integration, or mixing or combining new information with existing information into one psychological response; and
  3. Response, or the translation of the impression from the integration into an overall observable response or behavior.

Basically, it describes how one piece of information can be viewed and perceived differently by two individuals, based on the differences of their value and weight. As an illustration, let us take a look at two female employees talking about the maternity leave and benefits package offered by the company they work for, and why they have differing attitudes toward it.

Let’s call the first employee Mary. Mary is newly-wed, with plans of starting a family very soon. Let’s call the second employee Ashley. Unlike Mary, Ashley is committed to being single and prioritizing her career over building a family. For Mary, the package is definitely a good idea, since it is in line with her personal goals. It allows her to start a family and get back to her career. As a result, the package has a positive value.

Ashley, on the other hand, does not think the same. The package has negative value because of her opinion that the package merely encourages women to take a long break from work. From her perspective, this long break might derail any career opportunity that might present itself in the interim.

Clearly, the package holds more weight for Mary, since it is something that matters to her (specifically her plans to have children while remaining an employee of the company). It does not hold as much weight for Ashley, since it does not directly affect any of her immediate personal and career plans.

Although Ashley may start out looking unfavorably at the maternity package and its implications, the situation is not going to stay that way forever. When she obtains or learns new and positive pieces of information, a change of heart is likely to occur.

For example, she may not like the idea of giving up career opportunities in order to get pregnant and have a child. With that said, it’s likely that she is not entirely against the idea of having a child. Her only concern is allowing her career to suffer at the expense of motherhood. What was initially an uncaring attitude about putting family over career may be made lighter or more positive when she starts to know more about the joys of motherhood.

In essence, everybody is allowed to have an unfavorable or favorable attitude about something. However, these attitudes are not set in stone. They, too, can change, thanks to the integration of new information with already existing information. In fact, this integration can completely erase the old attitude and give rise to a new and totally different one, so don’t be surprised when Ashley is suddenly the first to take the package.

A really awesome in-depth presentation on the Integrated Information Theory of Consciousness.

The Theory of Reasoned Action

It was in 1980 when Martin Fishbein and Icek Ajzen developed and introduced the Theory of Reasoned Action, mainly as an enhancement of Anderson’s Information Integration Theory.

The enhancement comes in the inclusion of another factor into the equation: “behavioral intent” (or “behavioral intention”) and how, along with an individual’s pre-existing attitudes, these intentions can predict or even ultimately predict his responses or behaviors. In short, a person’s behavior will be affected or influenced, not only by his attitude or perceptions, but also by his expectations, or the anticipated outcomes that the behavior is likely to provide or lead to.

The Theory of Reasoned Action, or TRA, theory posits that behavioral intention is shaped by three elements or factors:

  1. The individual’s attitude, or personal opinion, on whether a specific behavior is good or bad, positive or negative, favorable or otherwise. The attitude must be specific, since this specificity will allow the prediction in the resulting behavior.
  2. The prevailing subjective norms, or the social pressure arising from other people’s expectations, as seen from the individual’s point of view. This, in turn, has two components:
    • The individual’s normative beliefs, or what he perceives to be what other people want or expect; and
    • The individual’s motivation, or need, to comply with what other people want or expect.
  3. The perceived behavioral control of the individual, or his perception of his ability to perform a specific behavior.

It is said that the “best predictor of behavior is intention”. To be more specific, we are referring to behavioral intention when we simply say intention, or the “cognitive indication of the readiness of an individual to perform a specific behavior”.

Thus, behavioral intention is seen as the precursor immediately leading up to the actual behavior, meaning a person will react or decide, depending on the behavioral intention formed or developed.

This relationship between the intention and the actual behavior is influenced by three conditions.

  • The behavioral intention must be specific, in order to predict a specific behavior;
  • The intention must remain constant or stable from the time it is given or measured until the time of actual performance of the behavior; and
  • The individual has full control on whether to perform the behavior or not, indicating complete volitional control, so that behavior is 100% voluntary.

In the Information Integrity Theory, an individual’s actions are influenced by his attitudes and perceptions. The TRA recognizes the reality that, although his attitudes indicate a specific behavior, his perceived social norms may contradict it, suggesting an entirely different response or behavior. This combination, which could mean reinforcement or contradiction, as the case may be, will be used to predict his behavioral intention.

Let’s face it: an intention is just an intention. It won’t always end up as an action. How many times have you intended to wake up early but you still snoozed when the alarm went off? This nature of an intention also happens to be the major argument against this theory.

Here comes another example: You have every intention to quit smoking and you have a commitment to completely abstain from the act and shun cigarettes. However, this intention alone is not enough proof that you will actually do it.

This means that the implementation of these intention is usually not 100%.Some behaviors are not totally voluntary. This gave rise to another way of looking at things, and that is the TPB.


The Theory of Planned Behavior (TPB) is seen as an improvement to the TRA, often mentioned and discussed with it. This makes sense, since the TPB reinforces and adds to the assumptions in the TRA.

The TPB maintains what TRA postulated about human behavior being governed by one’s attitudes and behavioral intentions characterized by the presence of social norms and the exercise of volitional control. However, it incorporates several modifications that allows for greater accuracy and reliability in understanding one’s attitudes and predicting his deliberate, planned, and resulting actual behavior.

Core Assumptions of TPB

Rational thinking finally enters the picture in this theory were, when employed, results in rational considerations that, in turn, influence and govern the choices, decisions, and behaviors of an individual.

The Theory of Planned Behavior upholds the key assumptions contained in the Theory of Reasoned Action, with certain modifications of its own.

  1. Deriving from the suppositions in TRA, the intentions of the individual largely reflects his personal attitudes, or their perception on the extent of favorability of an act. This will also be influenced by his perceived and cognitive beliefs about the act.
  2. Again, just like in TRA, the subjective norms that the individual is exposed or privy to will also have an impact on his intentions. This is in recognition of man being, by nature, a social creature, so that he will no doubt care about what others think or belief. More often than not, if society demonstrates general favorability toward an act, it is highly likely that the individual will think the same, his intentions largely shaped by the extent of approval (and disapproval) by family, friends, co-workers, or pretty much any person he trusts.
  3. The intentions and the resulting behaviors of the individual are affected by their perceived behavioral control, or what they think and believe to be their ability to actually perform or engage in the said behaviors. Succeeding literature on TPB led to the identification of the two clear facets of this perceived behavioral control:
    • Internal control: This is basically how the individual perceives his own control to be like. It focuses on how the individual sees himself as being in control when it comes to performing the specific behavior in question, and this mostly has a lot to do with the sufficiency of his knowledge, skills and abilities, and the amount of discipline he wields while performing the behavior.
    • External control: Other external factors also have a way of shaping how an individual behaves. For example, the acceptance or approval of family, friends, and peers is likely to influence a person into developing a positive attitude toward a behavior, bolstering his intention to see the specific action to the end. Time is also another factor that is external, but will no doubt impact one’s level of behavioral control.

The TPB is more cognizant of how it is highly probably for one’s intention to be completely different with behavior is deliberately planned and carried out. This is mostly traced to the divergence of the level of perceived behavioral control with that of the actual control exercised or employed.

We will understand this further as we take a look at the TPB Model or TPB Diagram.

The TPB Model

Ajzen and Fishbein presented the Theory of Planned Behavior Model, or a diagram that simplifies the key concepts of the theory. That model is presented below.


© Wikipedia Commons ∣ Robert Orzanna

Here is another representation of the same model.

© http://www.gov.scot/Publications/2008/01/07105336/3

The above diagram clearly presents the key variables of TPB, and they are grouped into three.

Behavioral Beliefs

An individual’s behavioral beliefs serve as the link between his Behavior to the Outcome that the behavior is expected to produce or bring about.

It is a person’s behavioral beliefs that will have a direct influence on his attitude toward a behavior. If the expected outcome is something favorable, then there is no doubt that he will also have a positive attitude toward the behavior, increasing the likelihood of actual performance.

Essentially, the behavioral beliefs of the person will focus on the issue on whether a behavior is favorable or unfavorable.

Normative Beliefs

If decisions on actions and behaviors were made solely by the individual, predicting his responses is definitely going to be easy as pie. However, since there are other – internal and external – factors at play, that is not the case.

Normative beliefs involve the key people or characters around the individual, specifically their behavioral expectations as he perceives them to be. On top of that, it is also shaped in part by the level of importance that he places on these people’s expectations. Together, these determine the subjective norm that will play an important part in his decisions on whether to behave in a certain way or not.

For example, a person is trying to decide whether he should quit smoking or not. He knows that smoking is something that his spouse, children and the co-workers he is in close proximity with at the office every day, find distasteful or unfavorable.

The opinion of his family is very important to him, so he feels that he needs to acquiesce with their preference for him not to smoke. However, it is a different story at the workplace. He could not care less what his co-workers think about his smoking habit, and the absence of a company rule or policy on smoking at work does nothing to motivate him to comply with what his co-workers want or expect.

As a result, his response is likely to be selective when it comes to smoking. When he’s at home or in the company of his family, he will not smoke. When at work, or with his co-workers, that’s the only time he will feel comfortable about smoking.

Control Beliefs

You may perceive the presence of factors (called ‘control factors’) that will have an impact on how the performance of the action will go. These are the control beliefs, which will dictate your perceived behavioral control. Each control factor can be viewed individually, and your perception of the power of one control factor may be different from the power of the other control factors. If there is a high probability that the powerful control factor is present, you are very likely to carry out the action in line with the powerful factor.

Let’s go back to the smoking example.

One control factor is a company policy on smoking in the workplace. If there is no specific policy or if there is one but it is not enforced, you will perceive the control factor to be weak, with no power at all. If, in contrast, there is a “no smoking within company premises” policy in place, with corresponding sanctions for offenders, it becomes so powerful as to have an influence on your behavioral control, and playing a major role in your consideration on whether to stop smoking at the workplace or not.

When combined, all three beliefs will result in your behavioral intention which will inevitably, will lead to the behavior itself. There is a direct relationship between these three elements. If both the attitudes and subjective norms are positive and you strongly believe that you can perform a specific behavior, then it is bound to strengthen your intention and resolve to actually behave in that expected manner.

However, if you take a closer look at the model, you will find that your perceived behavioral control does not cease to be relevant once the intention has been developed, since it will still affect the behavior. This means that even after starting the action, there is still a possibility that your perception of your ability to actually carry it through can still affect performance.

Scope and Applications of TPB

The Theory of Planned Behavior has found an extensive scope, being used in various fields and industries, and in varied applications. Not surprisingly, it has become widely used in the field of behavioral and psychological research and evaluation studies.

Ajzen himself used the TPB in various researches, such as the one he co-wrote on the applicability of TPB to Leisure Choice, published in the Journal of Leisure Research (1992) and, earlier, in 1991, on the applicability of TPB in predicting leisure participation, published in Leisure Sciences.

Whether it’s a social issue or a health issue, TPB has found acceptable applicability. Political entities rely on its concepts to predict voting behavior of electorates. Health care facilities, pharmacological companies, and even governments employ the key concepts of TPB in studying and predicting human behavior on matters such as disease prevention, birth control, and family planning, to name a few.

Businesses and organizations also accepted the application of TPB, recognizing its input when it comes to organizational processes and decision-making processes. In fact, even marketers found a great use for TPB, incorporating it in predicting market consumption, as well as the behavior of customers and competitors.

What makes the TPB more acceptable than, say, the TRA, is how it is cognizant of factors or elements that are out of the person’s control or full volition. The predictability of intentions and behavior is definitely higher than TRA, or other prior theories on predicting and understanding human behavior.

Granted, the TPB is not without its limitations, and the main argument against it is how it puts no value or importance on emotion, which is seen by many as one of the key elements that determine or drive one’s behavior. No doubt, the continuous study on human behavior, particularly on planned and reasoned actions and decisions, will result in better and more encompassing theories in the future. For now, the TPB does a great job at it, which explains its wide usage in various fields and industries.

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