The Theory of Planned Behaviour (TPB) has received considerable attention in the literature. The present study is a quantitative integration and review of that research. From a database of 185 independent studies published up to the end of 1997, the TPB accounted for 27% and 39% of the variance in behaviour and intention, respectively. The perceived behavioural control (PBC) construct accounted for significant amounts of variance in intention and behaviour, independent of theory of reasoned action variables. When behaviour measures were self-reports, the TPB accounted for 11% more of the variance in behaviour than when behaviour measures were objective or observed (R2s = .31 and .21, respectively). Attitude, subjective norm and PBC account for significantly more of the variance in individuals' desires than intentions or self-predictions, but intentions and self-predictions were better predictors of behaviour. The subjective norm construct is generally found to be a weak predictor of intentions. This is partly attributable to a combination of poor measurement and the need for expansion of the normative component. The discussion focuses on ways in which current TPB research can be taken forward in the light of the present review.

/pdf/efficacy-of-the-theory-of-planned-behaviour-a-meta-analytic-32gm69pazu.pdf

Efficacy of the Theory of Planned Behaviour: a meta-analytic review.

Conceptual and methodological ambiguities surrounding the concept of perceived behavioral control are clarified. It is shown that perceived control over performance of a behavior, though comprised of separable components that reflect beliefs about self-efficacy and about controllability, can nevertheless be considered a unitary latent variable in a hierarchical factor model. It is further argued that there is no necessary correspondence between self-efficacy and internal control factors, or between controllability and external control factors. Self-efficacy and controllability can reflect internal as well as external factors and the extent to which they reflect one or the other is an empirical question. Finally, a case is made that measures of perceived behavioral control need to incorporate self-efficacy as well as controllability items that are carefully selected to ensure high internal consistency.

Summary and Conclusions
Perceived control over performance of a behavior can account for consider- able variance in intentions and actions. However, ambiguities surrounding the concept of perceived behavioral control have tended to create uncertainties and to impede progress. The present article attempted to clarify conceptual ambiguities and resolve issues related to the operationalization of perceived behavioral control. Recent research has demonstrated that the overarching concept of perceived behavioral control, as commonly assessed, is comprised of two components: self-efficacy (dealing largely with the ease or difficulty of performing a behavior) and controllability (the extent to which performance is up to the actor). Contrary to a widely accepted view, it was argued that self-efficacy expectations do not necessarily correspond to beliefs about internal control factors, and that controllability expectations have no necessary basis in the perceived operation of external factors. Instead, it was suggested that self-efficacy and controllability may both reflect beliefs about the presence of internal as well as external factors. Rather than making a priori assumptions about the internal or external locus of self-efficacy and controllability, this issue is best treated as an empirical question.

Also of theoretical significance, the present article tried to dispel the notion that self-efficacy and controllability are incompatible with, or independent of, each other. Although factor analyses of perceived behavioral control items provide clear and consistent evidence for the distinction, there is sufficient commonality between self-efficacy and controllability to suggest a two-level hierarchical model. In this model, perceived behavioral control is the overarching, superordinate construct that is comprised of two lower-level components: self-efficacy and controllability. This view of the control component in the theory of planned behavior implies that measures of perceived behavioral control should contain items that assess self-efficacy as well as controllability. Depending on the purpose of the investigation, a decision can be made to aggregate over all items, treating perceived behavioral control as a unitary factor, or to distinguish between self-efficacy and controllability by entering separate indices into the prediction equation.

Perceived Behavioral Control, Self-Efficacy, Locus of Control, and the Theory of Planned Behavior

This paper describes and reviews the theory of planned behavior (TPB). The focus is on evidence supporting the further extension of the TPB in various ways. Empirical and theoretical evidence to support the addition of 6 variables to the TPB is reviewed: belief salience measures, past behaviodhabit, perceived behavioral control (PBC) vs. selfefficacy, moral norms, self-identity, and affective beliefs. In each case there appears to be growing empirical evidence to support their addition to the TPB and some understanding of the processes by which they may be related to other TPB variables, intentions, and behavior. Two avenues for expansion of the TPB are presented. First, the possibility of incorporating the TPB into a dual-process model of attitude-behavior relationships is reviewed. Second, the expansion of the TPB to include consideration of the volitional processes determining how goal intentions may lead to goal achievement is discussed.

Extending the Theory of Planned Behavior: A Review and Avenues for Further Research

The predictive power of the Ajzen, Triandis, and Schwartz models are compared in the context of car use for university routes. Two hundred fifty-four students filled out a questionnaire designed to measure the components of the three models. In the prediction of intention to use a car, results indicated that one variable from the Trinandis model—role beliefs—increased the explanatory power offered by the components of the Ajzen model. In the prediction of self-reported car use, one variable of the Triandis model—car use habit—significantly increased the predictive power of the Ajzen model. The central variable of the Schwartz model—personal norm—exerted no significant effect either on intention or on behavior. The implications of the findings for interventions to reduce the car use of students for university routes are discussed.

Incentives, Morality, Or Habit? Predicting Students’ Car Use for University Routes With the Models of Ajzen, Schwartz, and Triandis:

Predicting intentions to purchase organic food: The role of affective and moral attitudes in the Theory of Planned Behaviour

The cross-cultural validity of Fishbein and Ajzens theory of reasoned action Ajzens theory of planned behavior and Triandis theory of interpersonal behavior was tested and theories applied to understanding the intention to use a condom for each episode of sexual intercourse with a new partner in the Latin American English-speaking Caribbean and South Asian Canadian communities. The approximately 350 participants of mean age 26.8-31.0 years in each of the three groups were recruited from multiple ethnocultural venues. While there were approximately equal numbers of men and women represented in the Latin American and English-speaking Caribbean groups no South Asian woman participated. Cross-cultural validity was found among the three theories. However the theories of Ajzen and Triandis performed better than the theory of Fishbein and Ajzen. The authors recommend that role beliefs and moral norm be added to Ajzens model in the effort to maximize its predictive and explanatory ability.

Alix Adrien

Papers

Cross‐Cultural Testing of Three Social Cognitive Theories: An Application to Condom Use1