What is the theory of planned behavior in simple terms?

Whether you do something can be predicted from your intention, which depends on whether you think the behavior is good, whether people around you want you to do it, and whether you feel able to do it.

How does it differ from the theory of reasoned action?

The theory of reasoned action explained intention with attitudes and subjective norms only; the theory of planned behavior adds perceived behavioral control, how easy you feel the behavior is.

Theory of Planned Behavior

🧠 Psychology By CampusDown Wiki Editorial Team Last updated October 26, 2026

The theory of planned behavior is a social psychological theory holding that behavioral intention is the most direct predictor of behavior, and that intention is shaped by three factors: attitude toward the behavior, subjective norms and perceived behavioral control. It was proposed by Icek Ajzen.

Contents

1. From reasoned action to planned behavior
2. Components and measurement
3. The intention–behavior gap and critiques
4. FAQ
5. References

From reasoned action to planned behavior

Responding to findings that attitudes predict behavior only weakly, Martin Fishbein and Icek Ajzen (1975) proposed the theory of reasoned action (TRA). In it the immediate cause of behavior is behavioral intention, which is determined by a person's attitude toward the behavior and by subjective norms, the perceived wishes of important others. But TRA fit best for behaviors under full volitional control. Ajzen (1985, 1991) added perceived behavioral control (PBC), how easy or difficult a person feels the behavior is, to complete the theory of planned behavior. The concept is close to Albert Bandura's (1977) self-efficacy. PBC affects behavior indirectly through intention and directly to the extent that it reflects actual control.

Components and measurement

Each factor rests on underlying beliefs. Attitude derives from beliefs about a behavior's outcomes weighted by their evaluation (behavioral beliefs); subjective norm from the expectations of specific referents weighted by motivation to comply (normative beliefs); and PBC from beliefs about factors that facilitate or impede the behavior and their power (control beliefs). Researchers define the target behavior precisely in terms of target, action, context and time, and measure each factor with seven-point questionnaire items; predictive power is higher when this principle of compatibility is respected. TPB has been applied in thousands of studies of smoking cessation, exercise, condom use, green consumption, technology adoption and entrepreneurial intention. In Armitage and Conner's (2001) meta-analysis of 185 studies, TPB explained about 39 percent of the variance in intention and 27 percent in behavior.

The intention–behavior gap and critiques

The biggest problem is the intention–behavior gap: intentions often fail to translate into action. Sheeran (2002) reported that a large share of people with intentions do not act on them, and Webb and Sheeran (2006) showed experimentally that a medium change in intention produces only a small change in behavior. Peter Gollwitzer (1999) proposed implementation intentions, "when, where and how" plans, to narrow the gap. Wood and Neal (2007) noted that once behavior becomes habitual, situational cues rather than intentions drive it. Sniehotta et al. (2014) argued it was "time to retire" TPB because it fails to explain behavior change, while Ajzen (2015) replied that the theory remains valid and misapplication is the problem. Fishbein and Ajzen (2010) integrated the work into the reasoned action approach, and alongside motivation theories it remains a basic framework for designing behavior-change interventions.

FAQ

What is the theory of planned behavior in simple terms?: Whether you do something can be predicted from your intention, which depends on whether you think the behavior is good, whether people around you want you to do it, and whether you feel able to do it.
How does it differ from the theory of reasoned action?: The theory of reasoned action explained intention with attitudes and subjective norms only; the theory of planned behavior adds perceived behavioral control, how easy you feel the behavior is.

Sources reviewed: 2026-10-26

References

Ajzen, I. (1991). The theory of planned behavior. Organizational Behavior and Human Decision Processes, 50(2), 179–211.
Ajzen, I. (1985). From intentions to actions: A theory of planned behavior. In J. Kuhl & J. Beckmann (Eds.), Action Control (pp. 11–39). Berlin: Springer.
Fishbein, M., & Ajzen, I. (1975). Belief, Attitude, Intention, and Behavior. Reading, MA: Addison-Wesley.
Ajzen, I., & Fishbein, M. (1980). Understanding Attitudes and Predicting Social Behavior. Englewood Cliffs, NJ: Prentice-Hall.
Fishbein, M., & Ajzen, I. (2010). Predicting and Changing Behavior: The Reasoned Action Approach. New York: Psychology Press.
Armitage, C. J., & Conner, M. (2001). Efficacy of the theory of planned behaviour: A meta-analytic review. British Journal of Social Psychology, 40(4), 471–499.
Bandura, A. (1977). Self-efficacy: Toward a unifying theory of behavioral change. Psychological Review, 84(2), 191–215.
Sheeran, P. (2002). Intention–behavior relations: A conceptual and empirical review. European Review of Social Psychology, 12(1), 1–36.
Webb, T. L., & Sheeran, P. (2006). Does changing behavioral intentions engender behavior change? Psychological Bulletin, 132(2), 249–268.
Gollwitzer, P. M. (1999). Implementation intentions. American Psychologist, 54(7), 493–503.
Sniehotta, F. F., Presseau, J., & Araújo-Soares, V. (2014). Time to retire the theory of planned behaviour. Health Psychology Review, 8(1), 1–7.
Ajzen, I. (2015). The theory of planned behaviour is alive and well. Health Psychology Review, 9(2), 131–137.
Wood, W., & Neal, D. T. (2007). A new look at habits and the habit-goal interface. Psychological Review, 114(4), 843–863.

Reports and materials that use this theory (Korean)

There are no materials dedicated to this theory yet, but you can search related reports in the CampusDown library (Korean).

Find more reports · Search '계획된 행동이론' on CampusDown →

Motivation TheoriesMotivation theories compared: content theories (Maslow, Alderfer, Herzberg, McClelland), process theories (Vroom's expectancy, Adams's equity, Locke's goal setting) and Deci and Ryan's self-determination theory.🧠 Psychology Achievement Motivation TheoryAchievement motivation theory explained: McClelland's needs for achievement, affiliation and power, measuring them with the TAT, what high achievers prefer, Atkinson's expectancy-value model with the motive to avoid failure, and uses in school and work.🧠 Psychology Rational Choice TheoryWhat rational choice theory is, its core assumptions, applications to voting, collective action, the family and educational inequality, Coleman's social theory, Simon's bounded rationality, behavioral economics, and Green and Shapiro's critique.👥 Sociology Social identity theorySocial identity theory explained: Henri Tajfel's question after the Holocaust, the minimal group experiments, the three steps of categorization, identification, and comparison, how low-status groups respond, and uses in politics, fandom, and branding.🧠 Psychology Yerkes–Dodson LawWhat the Yerkes–Dodson law is: the 1908 mouse discrimination study, the inverted-U, optimal arousal by task difficulty, Hebb and Easterbrook, sport psychology models, norepinephrine research, and critiques of its popular distortion.🧠 Psychology

Latest ArticlesView all ›

New guides for college study and assignments (Korean)

This article was last updated on October 26, 2026. It is based on widely recognized original works and textbooks; when citing it in a paper, please check the original sources listed in the references.