The Reasoned Action Approach and the Theories of Reasoned Action and Planned Behavior

The authors comprehensively review research on the link between attitudes and behavior. They introduce the constructs of subjective norms and intentions, and outline the importance of correspondence in terms of target and action for precision in attitude-behavior relations. by subscription or purchase. This article reports two tests of the predictions of the theory of planned behavior, and provides a template for subsequent research designs and Measurement of theory constructs. It also demonstrates that the theory of planned behavior accounts for a greater amount of variance in behavior than the theory of reasoned action. Available online by subscription or purchase. This article reports a study in which relations between sets of salient behavioral beliefs and attitudes, control beliefs, and perceived behavioral control are tested using ‘partial’ correlations. Findings indicate that attitudes and perceived behavioral control tend to be uniquely associated with a small number of beliefs. Available online by subscription or purchase. the This article reports a test of predictions of the reasoned action approach in six health risk and six health protection behaviors. Instrumental and experiential attitudes, descriptive norms, and capacity predicted intentions for both risk and protection behaviors, while injunctive norms predicted intentions only for protection behaviors. Available online by subscription or purchase. behavior: and The authors report an effective comparison of the theory of planned behavior and the reasoned action approach, and demonstrate that the latter was superior in accounting for variance in intention and behavior. They also report a unique simulation analysis to show that large-sized changes in the theoretical constructs are necessary for small-to-moderate sized changes in intentions and behavior. Available online by subscription or purchase. higher-order normative behavioural the theory This article reports a test of the theory of planned behavior while simultaneously differentiating between affective and instrumental attitudes, descriptive and injunctive norms, and perceived control and self-efficacy. Results support the theory, and demonstrate the differentiated components are subsumed by higher order factors. Available online by subscription or The author reports a study using innovative designs to test the proposed directional and reciprocal effects of attitudes on behavior in the theory of reasoned action, including whether attitudes and subjective norms cause intentions, and whether effects of intentions on behavior met Tested the predictive validity of the theory of planned behavior for condom use over a one-year period using a ‘panel’ design in which all study measures, including behavior, were measured at both time points. The research demonstrated that constructs demonstrated considerable change over the year, and that past intentions and behavior were significant predictors of subsequent intentions. Available online by subscription or purchase. This article reports a meta-analytic comparison of the theories of reasoned action and planned behavior, and is the first to provide a meta-analytic test of the unique effects of self-efficacy and past behavior as additional predictors in the theory. A meta-analysis research the theory of planned behavior health behavior adopting prospective designs. Notable in examining effects of model relationships across different domains of health behavior risk behaviors, detection behaviors, physical activity, dietary behaviors, safe sex behaviors, and abstinence behaviors, as well as examining theory predictions controlling past behavior. meta-analysis studies testing predictions the action approach averaged effects This article provides the first meta-analysis of the theory of reasoned action. It provides a lucid introduction to the theory and its predictions, a quantitative summary of the research applying the theory across multiple behaviors, and the extent to which researchers have overstepped the boundary conditions of theory and the consequences of doing so. Available online by subscription or purchase. This article reports research to indicate that the stronger the relationship between past behavior and behavior, the weaker the intention-behavior relationship, findings which have been interpreted as the influence of habits or nonconscious processes on behavior. Available online by subscription or purchase. meta-analysis the size of the intention-behavior relationship on intenders,’ The authors apply meta-analysis to test the moderating role of multiple properties of the constructs from the theories (accessibility, temporal stability, direct experience, involvement, certainty, ambivalence, and affective-cognitive consistency) in moderating relations between theory constructs and behavior. Intention stability was found to be the most consistent moderator, and moderated all relations in the theory. Available online by subscription or purchase. This article reports research examining the effect of temporal stability and accessibility— measured by response latencies toward attitude stimuli—of theory constructs on relations between attitudes and behavior. Stability, but not accessibility, moderated the attitude– behavior relationship. Available online by subscription or purchase. This addresses the key issue of scale correspondence as a key boundary condition likely to affect relations among constructs in the theory of planned behavior. A study testing effects of variations in scale correspondence on intention-behavior relations is reported. Results indicate that violations of correspondence tended to attenuate intention-behavior relations. Available online by subscription or purchase. The authors use a unique ‘think-aloud’ technique to examine how individuals respond to scaled measures of the theory constructs. Content analysis of responses identify numerous problems including the potential for measures to introduce new thoughts, similar to the question-behavior effect, and the variability in opinions of salient others when responding to subjective norms questions. Available online by subscription or purchase. authors raise important issues relating to the interpretation of expectancy-value models of constructs from the theory of planned behavior, such as the types of response scale used and the testing of expectancy and value interactions. They propose some potential alternative scaling procedures as solutions. Available online by subscription or purchase. perceived controllability This article outlines the key conceptual developments in extending the theory of planned behavior, particularly the Measurement of beliefs and the inclusion of affective, control, and personal normative beliefs in the theory. Available online by subscription or purchase. The separate the perceived behavioral control construct into beliefs about controllability and beliefs about agency or capacity, which are aligned with the self-efficacy construct. Each of the components is shown to have independent effects on and behavior. Available online by subscription purchase. This article reports a series of experimental studies that corroborate the distinction between attitudes and perceived behavioral control in the theory of planned behavior, and further supports the independent effects of these constructs in predicting behavior. Available online by subscription or purchase. has extended the normative component of the of behavior to self-identity. Self-identity reflects individuals’ typically performs the behavior of interest, this analysis demonstrates that self-identity predicts intentions independent of subjective norms and other constructs the theory. meta-analysis of theory of planned behavior studies that included anticipated affect regret, and moral as predictors of and behavior alongside the theory constructs. Affective attitudes and moral norms by across studies. The authors present evidence which supports expanding the theory of planned behavior to encompass group-related from social identity theory. They demonstrate that individuals’ beliefs that the behavior is consistent with group norms predicted but only among individuals that identified with the group. Available online by subscription or purchase. This analysis tested whether intentions based on particular variables within the theory such as instrumental and affective attitudes; anticipated affective reactions; and injunctive, descriptive, and moral norms moderated the relationship between intentions and behavior. The research demonstrated that only individuals who based their intentions on affective attitudes had stronger relations between intentions and behavior. Available online by subscription or purchase. effects of the extroversion, conscientiousness, and neuroticism traits from the five-factor model of personality on behavior through the social cognitive constructs in the theory, but also found direct effects of extroversion on behavior. Available by subscription purchase. type of person A unique within-participants design was used to identify individuals whose intentions are based on perceived behavioral control rather than attitudes and subjective norms. This suggests the importance of tailoring interventions to target particular constructs in the theory for effective behavior change. Available online by subscription or purchase. The authors use a within-participants design to identify normatively-controlled individuals, whose intentions tend to be predominately determined by subjective norms. The research provides evidence that individual differences may explain observed variation in the effects of normative and personal beliefs on intentions and behavior in the theory. Available online by subscription or purchase. The authors show that past behavior moderates the effect of intentions on exercise behavior, providing illustration that routine exercising reduces the effects of intention, and, therefore, reasoned processes, on decisions to exercise. Available by or purchase. Influential meta-analysis demonstrating that effects of intentions on behavior vary depending on whether the behavior has been performed frequently in the past and whether it has been performed in stable, unchanging contexts. The researchers suggest that past behavior provides information on the extent to which behaviors are habitual. Available online. Paradoxical effects of experience: Past behavior both strengthens and weakens the intention–behavior relationship. Researchers demonstrate that the moderating effects of past behavior on intention–behavior relations are curvilinear. Effects of intentions are weaker at low and high levels of past behavior, suggesting that experience with the behavior has a stabilizing effect on intentions, but reduces effects of intentions as the behavior becomes more habitual. subscription or purchase. The researchers integrate predictions from social identity theory into the theory of planned behavior in the context of sustainable agricultural processes. Results indicated that individuals who strongly identified with groups using sustainable practices made decisions based on group norms. Available online by subscription purchase. The authors provide a wide-ranging commentary on the theories applied to health behavior, with the reasoned action approach as an example. They cover the importance of clarifying the theoretical domain for theories, prioritizing utility over generalizability, modifying the theory on the basis of performance across multiple studies, and adopting a consensus approach to theory development. Available online by subscription or purchase. Systematic review interventions aimed at changing health behavior based on the theory of planned behavior. Findings indicate that the theory constructs are usually used as process and outcome variables rather than as a basis for interventions, and that only half of the interventions reported change in intentions, and two-thirds change in behavior, with typically small effect sizes. Available online by subscription or purchase. A meta-analysis of experimental studies targeting change in each of the constructs from the theory of planned behavior is reported. Interventions changed each of the target constructs and, importantly, led to changes in behavior. online by subscription or purchase. The author presents a full experimental test of the theory of planned behavior, manipulating each theory construct individually and in combination. Only the manipulation of control beliefs resulted in behavior change, and other than an effect of the behavioral belief manipulation on attitudes, no other effects were found. Available online by subscription or purchase. theory planned meta-analyzed. Results revealed overall effects of the interventions on changes in the theory constructs and behavior, and that persuasion, planning, skills information provision methods changed individual theory interventions the theory of planned behavior sexual risk-taking behavior among heterosexuals. Results demonstrated effects of interventions on theory constructs and risk-taking behaviors, effects were small and highly variable across studies. online by subscription or purchase.


Introduction
Since the inception of the theory of reasoned action in late 1970s by Martin Fishbein and Icek Ajzen, the theories of reasoned action and planned behavior and, in its more recent incarnation, the reasoned action approach, have been among the most influential approaches to predicting and understanding intentional behavior. The theories have been widely applied across multiple behaviors, contexts, and populations. With their roots in attitude theory and the social cognitive tradition, the theories focus on individuals' beliefs with respect to future performance of a given behavior. The theory of reasoned action was the earliest version of the theory. The central construct of the theory is intention, a motivational construct that is considered the most proximal determinant of behavior. Intention reflects the extent to which an individual is likely to plan to do, and invest effort in pursuing, a given behavior. Intention is conceptualized as a function of two belief-based constructs: attitudes and subjective norms. Attitudes are positive or negative evaluations of performing the behavior in future, while subjective norms reflect beliefs that significant others would want them to perform the behavior. The theory of reasoned action demonstrated effectiveness in predicting variability in people's behavior across many contexts, populations, and behaviors. Ajzen modified the theory of reasoned action to account for behaviors that were not under the complete control of the individual. The theory of planned behavior introduced perceived behavioral control as an additional predictor of intentions. In circumstances where individuals' perceptions of control closely reflect actual control, perceived behavioral control would determine the strength of the Intention-Behavior Relationship. When their perceived behavioral control was high, individuals would be more likely to act on their intentions. Ajzen also proposed that when perceived behavioral control closely reflects actual control, it will directly predict behavior. Fishbein and Ajzen proposed the reasoned action approach as a further development in their theory based on research. The reasoned action approach extends the theory of planned behavior by differentiating between different subcomponents of the attitude, subjective norm, and perceived behavioral control constructs in the theory of planned behavior. The popularity of the theories is due to their relative simplicity and flexibility, as well as their effectiveness in accounting for substantive variance in behavior. The theories have also served as the basis for extended theories that encompass new constructs toward developing more comprehensive explanations of behavior, and to test salient processes that determine action such as the relationship between intentions and behavior. This annotated bibliography outlines key books, chapters, and articles that chart the progress of these theories from their origins and development to their application and extension. The list of readings offered in this bibliography is not exhaustive, but aims to provide readers with a representative overview of the origins of the theories, key theoretical are also met with reciprocal effects of behavior on intentions. Available online by subscription or purchase.
Reinecke, J., P. Schmidt, and I. Ajzen. 1996. Application of the theory of planned behavior to adolescents' condom use: A panel study. Journal of Applied Social Psychology 26.9: 749-772. DOI: 10.1111DOI: 10. /j.1559DOI: 10. -1816DOI: 10. .1996 Tested the predictive validity of the theory of planned behavior for condom use over a oneyear period using a 'panel' design in which all study measures, including behavior, were measured at both time points. The research demonstrated that constructs demonstrated considerable change over the year, and that past intentions and behavior were significant predictors of subsequent intentions. Available online by subscription or purchase.

Evidence Syntheses
Numerous meta-analyses of findings from research on the theories of reasoned action and planned behavior have been conducted. These quantitative syntheses have provided important information on the average size of effects among the key constructs in the theory and the variability across studies. Importantly, they have also presented opportunities to test key moderators of theory relations. Many meta-analyses have been conducted; some have been general in approach, while others have been confined to specific behavioral domains (e.g., exercise, alcohol consumption, condom use). Sheppard, et al. 1988 is the first meta-analysis of the theory of reasoned action, and uses it as a basis for recommending future modifications. Armitage and Conner 2001 is particularly noteworthy because it focuses on multiple behavioral domains and also examines relations between beliefs and direct measures of theory of planned behavior constructs. Meta-analyses have also been used to test predictions of the model across studies using the synthesized data, like Hagger, et al. 2002;Albarracín, et al. 2001;and McEachan, et al. 2011. By comparison, there are fewer tests of the reasoned action approach, and only relatively recently has there been sufficient data to facilitate a meta-analytic synthesis (see McEachan, et al. 2016). This article meta-analyzed research applying the theories of reasoned action and planned behavior to condom use, and provided a comparison of the theories as well as a first metaanalytic synthesis of the critical influence of past behavior in the theory. Available online by subscription or purchase.
A comprehensive meta-analysis of the theory of planned behavior across multiple behavioral domains, notable for its examination of relations among the belief-based measures of the theory constructs and the overarching 'direct' measures. Available online by subscription or purchase. Hagger, M. S., N. L. D. Chatzisarantis, and S. J. H. Biddle. 2002. A meta-analytic review of the theories of reasoned action and planned behavior in physical activity: Predictive validity and the contribution of additional variables. Journal of Sport and Exercise Psychology 24.1: 3-32. DOI: 10.1123/jsep.24.1.3 This article reports a meta-analytic comparison of the theories of reasoned action and planned behavior, and is the first to provide a meta-analytic test of the unique effects of self-efficacy and past behavior as additional predictors in the theory. This article reports a meta-analysis of studies testing predictions of the reasoned action approach across multiple health behaviors, and examines differences in the averaged effects between the theory constructs in health protection and health risk behaviors. This article provides the first meta-analysis of the theory of reasoned action. It provides a lucid introduction to the theory and its predictions, a quantitative summary of the research applying the theory across multiple behaviors, and the extent to which researchers have overstepped the boundary conditions of theory and the consequences of doing so. Available online by subscription or purchase.

Basic Processes and Moderators
The theories of reasoned action and planned behavior have provided a framework for exploring some basic processes that determine human behavior across multiple social contexts. An important effect in the theory of reasoned action is the link between attitudes and behavior, a classic topic of study within social psychology, and a focal topic of discussion by Fishbein and Ajzen in the readings discussed in General Overviews. Considerable attention has also been paid to the Intention-Behavior Relationship, arguably the cornerstone of the theories, and this subsection introduces a series of key readings on the subject. Researchers have also explored the role of Accessibility and Stability of the constructs from the theories, particularly intentions, as potential moderators of relations between their component constructs. This section outlines some examples of research articles that evaluate these moderator effects.

Intention-Behavior Relationship
Orbell and Sheeran 1998 is the first analysis to demonstrate that a substantive proportion of individuals who stated having an intention to act subsequently failed to participate in the intended behavior. This group was labeled the 'inclined abstainers.' Further support is provided by Rhodes and de Bruijn in an 'unsuccessful intenders' meta-analysis. Sheeran and Webb 2016 provides a useful overview of this 'intention-behavior' gap and salient contributing factors. Research has indicated a number of factors that might strengthen the intention-behavior relationship. A key hypothesis of the theory is that individuals with greater control over their behavior will be more likely to carry out their intentions. This moderating effect of perceived behavioral control on the intention behavior relationship has rarely been tested, but Steinmetz, et al. 2011 provides the most comprehensive treatment. An influential line of research on intention-behavior relations has focused on planning. Orbell, et al. 1997 pioneered this research within the theory of planned behavior, demonstrating that augmenting intentions with 'if-then' plans, known as 'implementation intentions,' improved intention enactment. In addition, Sheeran and Conner 2017 demonstrates that the extent to which predictors of intentions (e.g., attitudes, norms, perceived control) all support participating in the behavior, termed 'motivational coherence,' strengthens the intention-behavior relationship. Van Bree, et al. 2013 andNorman andConner 2006 demonstrate that people with strong habits, measured by self-report and past behavioral frequency, tend to exhibit weaker effects of intentions on behavior.
Norman, P., and M. T. Conner. 2006. The theory of planned behaviour and binge drinking: Assessing the moderating role of past behaviour within the theory of planned behaviour. British Journal of Health Psychology 11.1: 55-70.

DOI: 10.1348/135910705X43741
This article reports research to indicate that the stronger the relationship between past behavior and behavior, the weaker the intention-behavior relationship, findings which have been interpreted as the influence of habits or nonconscious processes on behavior. Available online by subscription or purchase.

DOI: 10.1177/0146167297239004
This article indicates how the formation of 'if-then' plans, or 'implementation intentions,' increases the likelihood of individuals acting on their intentions. The authors show that these 'post-intentional' plans aid individuals' recall of their intentions. Available online by subscription or purchase.
Orbell, S., and P. Sheeran. 1998. "Inclined abstainers": A problem for predicting healthrelated behaviour. British Journal of Social Psychology 37.2: 151-165. DOI: 10.1111DOI: 10. /j.2044DOI: 10. -8309.1998 Reports research demonstrating that a substantive proportion of individuals who state an intention to participate in health-related behavior fail to do so. An influential article that provided the impetus for subsequent research on the 'intention-behavior gap.' Available online by subscription or purchase. This article introduces the construct of 'motivational coherence.' Individuals whose direct antecedents of intentions from the theory of planned behavior (attitudes, subjective norms, and perceived behavioral control) were all aligned toward doing the behavior had stronger intention-behavior relations. Available online by subscription or purchase. Sheeran, P., and T. L. Webb. 2016. The intention-behavior gap. Social and Personality Psychology Compass 10.9: 503-518. DOI: 10.1111/spc3.12265 This article provides a comprehensive contemporary summary of research on the 'intentionbehavior gap' including origins and conceptual bases, summarizes the effect of candidate moderating factors, and identifies strategies that assist people to follow-through on their intentions. Available online by subscription or purchase.

Rhodes
Steinmetz, H., E. Davidov, and P. Schmidt. 2011. Three approaches to estimate latent interaction effects: Intention and perceived behavioral control in the theory of planned behavior. Methodological Innovations Online 6.1: 95-110. DOI: 10.4256/mio.2010.0030 Provides the most comprehensive treatment of the rarely tested moderating effect of perceived behavioral control on the intention-behavior relationship, demonstrating that higher levels of perceived behavioral control lead to stronger effects of intentions on behavior. Available online. This article examines the effect of stability of constructs (intentions, attitudes, subjective norms, perceived behavioral control) from the theories of reasoned action and planned behavior on relations among theory constructs. More stable intentions were found to be related to stronger relations between intentions and behavior, intentions and attitudes, and intentions and past behavior. Available online by subscription or purchase. The authors apply meta-analysis to test the moderating role of multiple properties of the constructs from the theories (accessibility, temporal stability, direct experience, involvement, certainty, ambivalence, and affective-cognitive consistency) in moderating relations between theory constructs and behavior. Intention stability was found to be the most consistent moderator, and moderated all relations in the theory. Available online by subscription or purchase.
Doll, J., and I. Ajzen. 1992. Accessibility and stability of predictors in the theory of planned behavior. Journal of Personality and Social Psychology 63.5: 754-765. DOI: 10.1037/0022-3514.63.5.754 This article reports research examining the effect of temporal stability and accessibilitymeasured by response latencies toward attitude stimuli-of theory constructs on relations between attitudes and behavior. Stability, but not accessibility, moderated the attitudebehavior relationship. Available online by subscription or purchase.

Measurement
Social psychologists interested in testing the predictions of attitude and social cognitive theories have emphasized the importance of the validity of scaled self-report measures of theory constructs. These issues are extremely pertinent to studies testing predictions of the theories of reasoned action and planned behavior, and the reasoned action approach. There are also additional measurement issues that have been considered in research testing the theories, and their potential to affect the validity and interpretation of these tests. Ajzen 2006 is an online resource that provides a comprehensive, freely accessible guide to measuring constructs from the theories. This section also identifies some of the key readings that discuss these salient measurement issues including issues on the correspondence of measures, such as a test of effects of types of correspondence on theory effects in Courneya 1994, and the use of expectancy-value measures of the belief systems that underpin constructs from the theoriessuch as the critique of expectancy x value models of attitudes, norms, and control in the theory in French and Hankins 2003. In addition, Darker and French 2009 outlines how individuals respond to and interpret scaled questions used to measure theory constructs, while Wood, et al. 2016 demonstrates that responding to measures of theory constructs, like questions on intentions and attitudes, can affect behavior, which is known as the questionbehavior, or mere measurement, effect. Taken together these works highlight the salient issues and important consideration when measuring constructs from the theories. This article addresses the key issue of scale correspondence as a key boundary condition likely to affect relations among constructs in the theory of planned behavior. A study testing effects of variations in scale correspondence on intention-behavior relations is reported. Results indicate that violations of correspondence tended to attenuate intention-behavior relations. Available online by subscription or purchase. The authors raise important issues relating to the interpretation of expectancy-value models of constructs from the theory of planned behavior, such as the types of response scale used and the testing of expectancy and value interactions. They propose some potential alternative scaling procedures as solutions. Available online by subscription or purchase. Consistent with the extensive literature on the potential for observation to change the phenomenon studied, this meta-analysis demonstrates that completion of measures of intentions and constructs from the theory of planned behavior has positive, but small, effects on behavior. Available online

Extending the Theories
An important feature of the theories of reasoned action and planned behavior is their relative parsimony while simultaneously accounting for substantive variance in behavior across multiple contexts and populations. This simplicity and capacity to explain behavior notwithstanding, there is a general acknowledgement that the theories provide only partial explanations of behavior. There is tacit agreement of the need to extend the theories by including additional constructs or processes with the goal of developing more comprehensive explanations of behavior, with the caveat that such extensions come at the cost of reducing parsimony. Ajzen 1991 (cited under General Overviews) and Ajzen 2011 (cited under Overviews) argue that these costs should be balanced against the relative gains in explaining behavior. There is recognition that modification and extension of theories is inevitable for progress in understanding. The development of the theory of planned behavior and the reasoned action approach exemplifies this process as they both represent extensions of their predecessors. Overviews provides readings that chart the progress of the theories and summarize developments in theoretical and empirical research that have extended the theories. Subsequent sections provide examples of how theorists and researchers have extended the theories, particularly the theory of planned behavior, by Differentiating Constructs of the theory, augmenting the theory with Additional Constructs, including Personality and Individual Differences, accounting for Past Behavior and Habit, and developing Integrated Approaches that combine the theories with others.

Overviews
The issue of the sufficiency of the theory of planned behavior is explicitly discussed in Ajzen 2011, which outlines the potential value of extending the theory through the inclusion of Additional Constructs and processes that account for unique variance in behavior, or moderate relations between factors. The review articles Conner and Armitage 1998 and Manstead and Parker 1995 focus on the conceptual and empirical bases for adding key constructs in the theories including belief salience, self-efficacy, anticipated regret and moral norms, self-identity, and affective beliefs. In this article Ajzen identifies salient issues in the development of the theory of planned behavior in health contexts, and outlines the prerequisite conditions for additional variables to be included in the theory. Available online by subscription or purchase.
Conner, M., and C. J. Armitage. 1998. Extending the Theory of Planned Behavior: A review and avenues for further research. Journal of Applied Social Psychology 28.15: 1429-1464. DOI: 10.1111DOI: 10. /j.1559DOI: 10. -1816DOI: 10. .1998 This article outlines the conceptual and empirical bases for extending the theory of planned behavior. The inclusion of belief salience, Past Behavior and Habit, moral norms, selfidentity, and affective beliefs is considered, as well as making distinctions between perceived controllability and self-efficacy. Available online by subscription or purchase. This article outlines the key conceptual developments in extending the theory of planned behavior, particularly the Measurement of beliefs and the inclusion of affective, control, and personal normative beliefs in the theory. Available online by subscription or purchase.

Differentiating Constructs
Theorists have recognized that the core constructs of the theories of reasoned action and planned behavior should be both conceptually and empirically distinct, and that the constructs themselves could be differentiated into multiple distinct components. Researchers therefore have sought to design studies to test these distinctions, and whether these distinctions have value in accounting for unique variance in intentions and behavior, an important prerequisite for adding constructs. For example, Miniard and Cohen 1981 and Trafimow and Fishbein 1995 test whether people have the capacity to distinguish between attitudes and norms, and Trafimow and Duran 1998 tests whether people can differentiate attitudes and perceived behavioral control. The research supports these distinctions, providing confirmation for attitudes, subjective norms, and perceived behavioral control as distinct constructs. There have been further demonstrations that the constructs within the theory can be differentiated, such as Trafimow and Sheeran 1998, which makes the distinction between the affective and cognitive components of attitudes; Sheeran and Orbell 1999, which differentiates between descriptive and injunctive norms; and Terry and O'Leary 1995 which makes the distinction between perceived controllability and self-efficacy. These distinctions have paved the way for the broader reasoned action approach, which explicitly makes these distinctions clear while at the same time retaining the overarching constructs. The authors offer a critique of the conceptual and empirical basis of distinguishing between the behavioral and normative sets of beliefs that underpin the attitude and subjective norm constructs in the theory of reasoned action. Their study highlights the empirical consequences of strong relations between the constructs in predicting intention. Available online by subscription or purchase. Sheeran, P., and S. Orbell. 1999. Augmenting the theory of planned behavior: Roles for anticipated regret and descriptive norms. Journal of Applied Social Psychology 29.10: 2107-2142. DOI: 10.1111DOI: 10. /j.1559DOI: 10. -1816DOI: 10. .1999 The subjective norms construct encapsulates beliefs in the expectations of significant others. This article expands the normative component of the theory to include descriptive norms, which reflects beliefs in what significant others themselves do, and demonstrates its uniqueness in the prediction of behavior within the theory. Available online by subscription or purchase.
Terry, D. J., and J. E. O'Leary. 1995. The theory of planned behaviour: The effects of perceived behavioural control and self-efficacy. British Journal of Social Psychology 34.2: 199-220. DOI: 10.1111DOI: 10. /j.2044DOI: 10. -8309.1995 The authors separate the perceived behavioral control construct into beliefs about controllability and beliefs about agency or capacity, which are aligned with the self-efficacy construct. Each of the components is shown to have independent effects on intentions and behavior. Available online by subscription or purchase. Trafimow, D., and A. Duran. 1998. Some tests of the distinction between attitude and perceived behavioural control. British Journal of Social Psychology 37.1: 1-14. DOI: 10.1111DOI: 10. /j.2044DOI: 10. -8309.1998 This article reports a series of experimental studies that corroborate the distinction between attitudes and perceived behavioral control in the theory of planned behavior, and further supports the independent effects of these constructs in predicting behavior. Available online by subscription or purchase. This article reports experimental evidence for distinct affective and cognitive attitude components in the theory of planned behavior. The research indicates that people hold both cognitive beliefs, which reflect the instrumentality of the behavior, and affective beliefs, which reflect their emotive evaluation of the behavior. Available online by subscription or purchase.

Additional Constructs
Numerous extensions of the theories of reasoned action and planned behavior have been proposed, including additional constructs alongside the traditional predictors of intentions and behavior in the theory. These extensions have been advocated by numerous researchers and are consistent with the suggestion in Ajzen 1991 (cited under General Overviews) that the theory is open to the inclusion of additional variables provided they account for additional variance in intentions or behavior once the traditional theory constructs had been accounted for. The theory therefore serves as a flexible framework to explore the effects of multiple social cognitive constructs on intentional behavior. Many of the additional constructs included in the theories have focused on broadening the content of the additional predictors. This study demonstrates the importance of incorporating moral norms-that is, whether or not doing the behavior is consistent with the individuals' moral beliefs-into the theory of planned behavior. The intention-behavior relation was stronger among people with high moral norms who construed the behavior in moral terms. Available online by subscription or purchase. The authors demonstrate the importance of segregating the affective and cognitive components of attitudes across fourteen behaviors. Affective attitudes predicted behavior directly as well as indirectly through intentions for nine behaviors. The authors argue that decisions to act may be based on emotion independent of intentions in some behaviors. Available online by subscription or purchase. This meta-analysis summarizes research that has extended the normative component of the theory of planned behavior to encompass self-identity. Self-identity reflects individuals' beliefs that they identify as someone who typically performs the behavior of interest, and this analysis demonstrates that self-identity predicts intentions independent of subjective norms and other constructs in the theory. Available online by subscription or purchase. The authors meta-analyze research including descriptive norms as an additional predictor in the theory of planned behavior, and demonstrate across studies that descriptive norms accounts for unique variance in intentions beyond effects of subjective norms. Available online by subscription or purchase. The authors present evidence which supports expanding the theory of planned behavior to encompass group-related perceptions from social identity theory. They demonstrate that individuals' beliefs that the behavior is consistent with group norms predicted intentions, but only among individuals that identified with the group. Available online by subscription or purchase.

Personality and Individual Differences
The constructs from the theories of reasoned action and planned behavior, as well as the reasoned action approach, are operationalized as social cognitive beliefs about future participation in a given behavior. They are, therefore, subject to change and modification over time. However, theorists have been interested in the role of individual difference constructs, particularly personality traits, in determining behavior and how they relate to the social cognitive determinants of intentions and behavior in these theories. As individual difference and personality constructs reflect relatively stable, enduring factors that are likely to affect multiple behaviors and operate across multiple constructs, their effects are likely to be modest compared to those that are more proximal and dependent on situational and contextual factors, such as belief-based constructs. Researchers have extended the theories to incorporate traits. Traits have typically been treated as distal determinants of intentions and behavior mediated by the social cognitive constructs in the theory. Traits therefore serve as intrapersonal sources of information for the social cognitive beliefs. Furthermore, direct effects of traits on behavior independent of the social cognitive constructs seem to indicate decisions made independent of cognition. There are also suggestions that particular traits moderate effects among theory constructs, and, therefore act as 'biases' to decision making. Conner and Abraham 2001;Courneya, et al. 1999;and Hoyt, et al. 2009 incorporate traits from the five-factor model of personality, particularly conscientiousness and extroversion, as predictors of the theory of planned behavior constructs. Alongside this research, researchers have also demonstrated how generalized tendencies for intentions to be determined by particular constructs from the theory influence predictions in the theory. For example, Trafimow and Finlay 1996 demonstrates that individuals that base their intentions on subjective norms had stronger effects of subjective norms on intentions in the theory. Conscientiousness is found to be a consistent distal predictor of behavior through the theory's constructs and intentions, for health protection and exercise behaviors. A direct effect of conscientiousness was also found for exercise behavior. Available online by subscription or purchase. The authors demonstrate that the activity and self-discipline facets of conscientiousness and extroversion from the five-factor model of personality predicted behavior through the social cognitive constructs. Individuals low in the anxiety facet of neuroticism exhibited weaker intention-behavior relations. Available online by subscription or purchase. A unique within-participants design was used to identify individuals whose intentions are based on perceived behavioral control rather than attitudes and subjective norms. This suggests the importance of tailoring interventions to target particular constructs in the theory for effective behavior change. Available online by subscription or purchase. Trafimow, D., and K. A. Finlay. 1996. The importance of subjective norms for a minority of people: Between-subjects and within-subjects effects. Personality and Social Psychology Bulletin 22.8: 820-828. DOI: 10.1177/0146167296228005

Conner
The authors use a within-participants design to identify normatively-controlled individuals, whose intentions tend to be predominately determined by subjective norms. The research provides evidence that individual differences may explain observed variation in the effects of normative and personal beliefs on intentions and behavior in the theory. Available online by subscription or purchase.

Past Behavior and Habit
The theories of reasoned action and planned behavior, and the reasoned action approach, are all focused on predicting people's future behavior. Tests of the theory typically measure behavior at a later point in time, which should correspond with the time frame referred to in measures of the theory constructs. Inclusion of measures of past behavioral frequency as predictors of subsequent behavior alongside other theory measures enables evaluation of extent to which the theory constructs account for effects of past behavior on subsequent behavior-a test of the sufficiency of the theory. Research such as the meta-analysis Hagger, et al. 2018 demonstrates substantial effects of past behavior on subsequent behavior, and also shown that effects among the theory constructs, particularly the Intention-Behavior Relationship, are reduced in size. Ajzen 2002 suggests that attenuation of model effects could capture the extent to which individuals have formed similar beliefs in the past. Simultaneous effects of theory constructs and past behavior on the theory may indicate different 'pathways' to behavior: a reasoned pathway reflected by the effects of the theory constructs and intentions, and a 'habitual' or 'nonconscious' pathway represented by past behavior effects. Research has suggested that features of the behavior may determine relative strength of intentions and past behavior. Ouellette and Wood 1998, for example, demonstrates that behaviors which individuals have high opportunity to perform, and tend to be performed in stable contexts, are likely to become habitual and less dependent on intentions. Therefore the extent to which individuals' behavior is determined by their past behavior-and, therefore, the sufficiency of the theory-largely depends on the type of behavior, the frequency with which it has been previously performed, and whether it has been performed regularly in stable contexts. Consistent with this research, other studies have shown that past behavior moderates effects of theory variables on behavior, particularly the intention-behavior relationship. For example, Norman, et al. 2000 finds stronger intention-behavior effects with higher past behavior, suggesting greater habitual control over behavior. However, moderator effects have been inconsistent, and Sheeran, et al. 2017 suggests that moderating effects of past behavior in the intention-behavior relationship may be due to a stabilizing effect on intentions in the early stages of behavioral participation, but an attenuating effect after it has been performed regularly. Finally, research such van Bree, et al. 2015 demonstrates that the effects of past behavior have been shown to be mediated by habit. Importantly, some types of behavior are less subject to past behavior and habitual effects. For example, Bamberg, et al. 2003 demonstrates that past behavior has a modest effect on behavior over time even though the behavior has been repeated frequently.
Researchers demonstrate that the moderating effects of past behavior on intention-behavior relations are curvilinear. Effects of intentions are weaker at low and high levels of past behavior, suggesting that experience with the behavior has a stabilizing effect on intentions, but reduces effects of intentions as the behavior becomes more habitual. Available online by subscription or purchase. Research demonstrating that the effect of past behavior on subsequent behavior in the theory of planned behavior is partially mediated by self-reported habit, indicating that the residual effect of past behavior may be partially attributable to habit.

Integrated Approaches
Although the theories of reasoned action and planned behavior have been shown to be adequate in predicting behavior, substantial variance remains unexplained. There are also numerous limitations and boundary conditions of the theories, such as the residual effect of past behavior and inadequacy of the theory constructs to fully encompass all sets of beliefs that may determine behavior, such as the subjective norms construct. Although extending the theory to include Additional Constructs consistent with Ajzen 1991 (cited under General Overviews) has demonstrated utility, researchers have sought to use the theories as a basis for more comprehensive theories that draw from processes and constructs from other theoretical perspectives. Prominent integrated approaches have augmented the theories with individual difference and predisposing factors that serve as antecedents of the social cognitive constructs, and with additional components, such as planning and perceived barriers, that act as moderators of the intention-behavior relationship (de Vries, et al. 2005). There have also been attempts to include constructs and predictions from dual-process theories of behavior. The theories suggest that behavior is a function of reflective, reasoned decision making, as well as automatic, nonconscious processes that affect behavior beyond an individual's awareness. In the integrated approach, the social cognitive constructs and their effects from the theory of planned behavior and reasoned action approach represent reflective processes, and the theory is augmented to include constructs and predictions that represent nonconscious, automatic processes. Hagger, et al. 2017 typifies this approach in incorporating a measure of implicit attitudes toward behavior as an independent predictor of behavior in the theory of planned behavior. Research has also extended the theory to include broader perceptions beyond beliefs about behavior. Perugini and Conner 2000 presents an extended model of goal directed behavior, which not only differentiates between desires and intentions, but also incorporates constructs relating to the goals people pursue as a result of the behavior, such as goal feasibility. Consistent with suggestions that the subjective norms construct may be inadequate in accounting for normative influences on behavior, researchers have incorporated numerous additional constructs related to social and normative influences. Fielding, et al. 2008 takes this approach further and incorporates predictions from social identity theory, a prominent approach to group dynamics, into the theory of planned behavior. The research examined key processes relating to typical practices (group norms) and strength of identification with the group (group identification) on relations among theory of planned behavior constructs. A final example of an integrated approach is proposed by Montaño and Kasprzyk 2015 which draws from the theories of reasoned action and planned behavior to present an integrated model. The model accounts for more comprehensive sets of beliefs in the theories based on extensions, and serves as a precursor to the reasoned action approach. An integrated change model is proposed which incorporates constructs and processes from multiple social cognitive, individual difference, motivation, and stage models, with the theory of planned behavior at its root. Available online by subscription or purchase. The researchers integrate predictions from social identity theory into the theory of planned behavior in the context of sustainable agricultural processes. Results indicated that individuals who strongly identified with groups using sustainable practices made decisions based on group norms. Available online by subscription or purchase. The authors introduce and test a dual-process, dual-phase model in the context of sugar consumption. The model tests effects of implicit attitudes, representing nonconscious processes, and action planning, representing a volitional phase of action, on intentions and behavior alongside constructs from the theory of planned behavior. Available online by subscription or purchase. Montaño, D. E., and D. Kasprzyk. 2015. Theory of reasoned action, theory of planned behavior, and the integrated behavioral model. In Health behavior and health education: Theory, research, and practice. 5th ed. Edited by K. Glanz, B. K. Rimer, and K. Viswanath, 95-124. San Francisco: Jossey-Bass.
The authors describe the development of an integrated behavioral model resulting from a review of theories and apply it to prevention strategies in people with high HIV risk. The model includes constructs from the theory of planned behavior, with knowledge and skills to perform the behavior, salience of the behavior, environmental constraints, and habit as additional direct predictors of behavior. The authors introduce an extended model of goal-directed behavior, which not only distinguishes between desires and intentions, but also includes constructs relating to goal pursuit, particularly goal desires and goal feasibility. They demonstrate that goal desires are independent predictors of desire to perform the behavior, and that goal feasibility is a determinant of perceived control over the behavior.

Critiques and Commentaries
The theories of reasoned action and planned behavior, as well as the reasoned action approach, have demonstrated utility in identifying the social cognitive determinants of behavior; accounted for considerable variance in behavior across multiple behaviors, contexts, and populations; demonstrated flexibility in accounting for other constructs and processes; and helped inform the development of behavior change interventions. There have, however, been numerous critiques of the theory. This section contains articles that have criticized the theory, and the accompanying responses to the critiques, as well as articles that offer different perspectives on the theory and its application. Prominent critiques of the theory are found in Ogden 2003, Weinstein 2007, and Sniehotta, et al. 2014. Ogden 2003 identifies problems with falsifiability of the theory and, recognizing that some of the effects in the model are often not found in empirical tests, asks what sort of data is needed to reject the theory. Weinstein 2007 suggests that correlational predictive studies, even those predicting behavior over time, offer very limited evidence to support the theory, and the lack of experimental data is important. Sniehotta, et al. 2014 acknowledges the contribution that the theory has made to advancing understanding of behavior, but also identifies a series of limitations including those raised by Ogden and Weinstein, as well as the lack of utility of the theory in informing interventions to change behavior. Sniehotta even goes as far as to suggest that the theory should be 'retired'. Ajzen and Fishbein 2004 and Ajzen 2015 respond directly to Ogden and Sniehotta's criticisms, along with numerous other theorists. The general consensus is that the theory, and empirical evidence for the theory, is evolving to address the shortcomings. Head and Noar 2014 raises important issues regarding how to progress theories such as the reasoned action approach, particularly on issues such as specifying theoretical domains, generalizability and utility, the validity of including of Additional Constructs, and how organizations should track change in theories to inform interventions. Trafimow 2009 and Trafimow 2012 present an interesting counterpoint to criticisms on falsifiability indicating that the theory of reasoned action stands up to 'reasonable standards' of falsification, and also outline the importance of considering auxiliary assumptions when testing the theory. Taken together, these perspectives epitomize taking a critical approach when evaluating theory, and identify how these debates have utility in raising questions regarding current thinking and setting the agenda for future theory development and directions for subsequent research.
Ajzen, I. 2015. The theory of planned behavior is alive and well, and not ready to retire. Health Psychology Review 9.2: 131-137. DOI: 10.1080DOI: 10. /17437199.2014 In this commentary, Ajzen responds directly to the critique of Sniehotta, et al. 2014 and provides suggestions on how the theory has been effective in predicting behavior, is not static but takes into account feedback and change in its focal constructs, and can be used successfully as a basis for behavior change interventions. Available online by subscription or purchase. In this critique, the author outlines problems with the theory, particularly with respect to its falsifiability, and proposes the theory is too general to be practicable, and that relations among constructs reflect analytic 'truths' that are correct by definition rather than through exploration. Available online by subscription or purchase. The authors provide a wide-ranging critique of the theory of planned behavior, claiming that it does not sufficiently account for effects of multiple extraneous factors and that it lacks utility in informing interventions. The authors advocate the generation of new theories that incorporate components free from assumptions and are testable experimentally. Available online by subscription or purchase. The author provides informative commentary on claims the theory of reasoned action is not falsifiable by demonstrating that the theory makes 'risky predictions,' which are likely to be wrong if the theory is wrong, such as the distinction between attitudes and subjective norms, and demonstrates how these have been confirmed experimentally. The author also comments on the importance of specifying auxiliary assumptions on which theory predictions are conditional when testing predictions. Available online by subscription or purchase. This article highlights the inherent limitations in correlational studies as a means to provide evidence to support social cognitive theories like the theories of reasoned action and planned behavior. The author highlights the importance of experimental and quasi-experimental research to confirm predictions among theory constructs and behavior. Available online by subscription or purchase.

Interventions and Behavior Change
Can the theories of reasoned action and planned behavior, and the reasoned action approach, inform campaigns and initiatives to change behavior? A key critique of the theories, outlined in the previous section, is their lack of utility as a basis for behavior change interventions. The lack of utility is also compounded by an evidence base rife with correlational designs in which intervention and experimental research is underrepresented. However, evidence is accumulating that manipulations and intervention strategies that target change in the constructs from the theories do affect change in behavior. This section contains studies that outline such applications of the theories to changing behavior. Hardeman, et al. 2002 suggests that some interventions based on the theory can be effective in changing intentions and behavior, but with small effect sizes, and studies do not often provide clear descriptions or explanations of how the theory was applied in developing the reported intervention. Ajzen and Manstead 2007 outlines conceptual and theoretical bases of how the theories can be used to inform interventions. Examples of primary research testing effects of theory-based interventions and field experiments and experiments in changing behavior, such as Montanaro and Bryan 2014;Montanaro, et al. 2018;and Sniehotta 2009, are outlined. This section also reports research that has synthesized experimental and intervention evidence on the theories applied to behavior change, such as Albarracín, et al. 2005;Sheeran, et al. 2016;Tyson, et al. 2014;and Webb and Sheeran 2006. Importantly, it also includes research reports that have identified the specific behavior change methods or strategies that have been useful in changing constructs from the theory. For example, the meta-analysis Steinmetz, et al. 2016 andthe experiment Montanaro, et al. 2018 identify persuasion, provision of information, and behavioral skills training as key theory-based behavior change strategies. Experimental and intervention research based on the theories have generally shown effects on changing the targeted constructs and behavior; such effects, however, are highly variable. The field is moving toward identifying and refining the specific methods that target change in the constructs, and testing their effectiveness in changing behavior. This article summarizes basic research on the theory of planned behavior as a basis for intervention design, and highlights the role of the theory in identifying the specific beliefs relevant to the behavior, context, and population that should be targeted in interventions. They also identify that the theory itself does not specify how the beliefs could be changed. Systematic review of interventions aimed at changing health behavior based on the theory of planned behavior. Findings indicate that the theory constructs are usually used as process and outcome variables rather than as a basis for interventions, and that only half of the interventions reported change in intentions, and two-thirds change in behavior, with typically small effect sizes. Available online by subscription or purchase.

DOI: 10.1037/a0033969
Important study demonstrating that an intervention based on the theory of planned behavior was effective in changing condom use relative to a control group and an intervention based on an alternative theory, the health behavior model. The study also demonstrated attitude and self-efficacy change concurrent with behavior change. Available online by subscription or purchase.
Montanaro, E. A., T. S. Kershaw, and A. D. Bryan. 2018. Dismantling the theory of planned behavior: Evaluating the relative effectiveness of attempts to uniquely change attitudes, norms, and perceived behavioral control. Journal of Behavioral Medicine 41.6: 757-770 DOI: 10.1007/s10865-018-9923-x The authors report an experiment testing whether interventions changing each construct from the theory of planned behavior were more effective in changing risky sexual behaviors independently, or in combination. The study demonstrated that although the intervention targeting all constructs was more effective in intention change, the individual constructs were more effective in changing behavior. Available online by subscription or purchase. The author presents a full experimental test of the theory of planned behavior, manipulating each theory construct individually and in combination. Only the manipulation of control beliefs resulted in behavior change, and other than an effect of the behavioral belief manipulation on attitudes, no other effects were found. Available online by subscription or purchase. Interventions based on the theory of planned behavior were meta-analyzed. Results revealed overall effects of the interventions on changes in the theory constructs and behavior, and that persuasion, planning, skills provision, and information provision methods changed individual theory constructs but not behavior. Available online by subscription or purchase. A meta-analysis of studies targeting change in behavioral intentions, mainly based on the theories of reasoned action and planned behavior, is presented. Results indicated that that interventions led to significant changes in intentions and behavior, but the changes in intentions were much larger than changes in behavior. Available online by subscription or purchase.