THEORY OF PLANNED BEHAVIOUR AND HEALTH BEHAVIOUR

1-. General background

TPB is an extension of the earlier TRA. Both models imply that people´s attitudes are formed after careful consideration of available information.

The TRA origins are in Fishbein´s work on the psychological processes by which attitudes cause behaviour and in an analysis of the failure to predict behaviour from individual’s attitudes. The TRA used an expectancy-value framework to explain the relationship between beliefs and attitudes, and interposed a new variable, behavioural intention, between attitudes and behaviour

The principle of compatibility: (Ajzen 1988). This principle holds that each attitude and behaviour has the four elements of action, target, context and time, and states that correspondence between attitudes and behaviour will be greatest when both are measured at the same degree of specificity with respect to each element. Hence, any behaviour consists of:

(a) An action (or behaviour)(b) Performed on or toward a target or object(c) In a particular context(d) At a specified time or occasion.

Attitudes and behaviour will be most strongly related when both are assessed at the same level of specificity with regard to these four elements. Thus, general attitudes should predict general classes of behaviours and specific attitudes should predict specific behaviours.

2-. Description of the model

The TRA suggests that the proximal determinant (or cause) of volitional behaviour is one´s behavioural intention to engage in that behaviour. Behavioural intention represents a person´s motivation in the sense of her or his conscious plan, decision or self-instruction to exert effort to perform the target behaviour. Attitudes towards a specific behaviour impact on performance of the behaviour via intentions. Thus in the TRA the issue of how the unobservable attitude is transformed into observable action is clarified by interposing another psychological event: the formation of an intention between the attitude and the behaviour. However, the theory is less clear about the factors that lead attitudes to be translated into intentions. One possibility is that it is the anticipated opportunity to perform the behaviour that promotes the formation of an intention. The TRA includes a second determinant of intention: subjective norm represents the perceived social pressure from others to perform the target behaviour. The TRA restricts itself to the prediction of volitional behaviours.

The TPB was developed to broaden the applicability of the TRA beyond purely volitional behaviours by incorporating explicit consideration of perceptions of control over performance of the behaviour as an additional predictor of behaviour. Considerations of perceptions of control, or perceived behavioural control (PBC), are important because they extend the applicability of the theory beyond easily performed, volitional behaviours to those complex goals and behaviours which are dependent upon performance of a complex series of other behaviours. It is this lack of actual control which attenuates the power of intentions to predict

behaviour. However, given the myriad of problems defining and measuring actual control, PBC have tended to be employed. This inclusion of PBC in the TPB provides information about the potential constraints on action as perceived by the actor, and explains why intentions do no always predict behaviour. TPB describes behaviour as:

B = w₁BI + w₂PBC (1)

Where B is behaviour, BI is behavioural intention, PBC is perceived behavioural control, and w₁ and w₂ are regression weights.

The link between intention and behaviour reflects the fact that people tend to engage in behaviours they intend to perform. However, the link between PBC and behaviour is more complex, PBC is held to exert both direct and interactive (with behavioural intentions) effects on behaviour. This is based on the following rationale: that however strongly held, the implementation of an intention into action is at least partially determined by personal and environmental barriers. Therefore, in situations where prediction of behaviour from intention is likely to be hindered by the level of actual control (i.e. volitional), PBC should (a) facilitate the implementation of behavioural intentions into action and (b) predict behaviour directly. PBC will predict behaviour directly to the extent that the measure matches actual control.

Determinants of intention

In the TRA, attitudes are one predictor of behavioural intention. Ajzen define an attitude as “a learned disposition to respond in a consistently favourable or unfavourable manner with respect to a given object”. Applying the principle of compatibility, the relevant attitudes are those toward performance of the behaviour, assessed at a similar level of specificity to that used in the assessment of behaviour.

The TRA also specifies subjective norm as the other determinant of intentions, they consist of a person´s beliefs about whether significant others think he/she should engage in the behaviour. Subjective norms are assumed to assess the social pressures individuals feel to perform or not perform a particular behaviour from salient referents.

The TPB incorporates a third predictor of intentions, PBC, which is the individual´s perception of the extent to with performance of the behaviour, is easy or difficult.

BI = w₃A + w₄SN + w₅PBC (2)

The equation indicates that intentions are a function of one´s evaluation of personally engaging in the behaviour, one´s perception that significant others think you should or should not perform the behaviour, and perceptions of one´s control over performance of the behaviour. Without the PBC component, equation 2 represents the TRA. It is worth noting that, unlike other variables, PBC has links with both intentions and behaviour component in the TPB. The PBC-intention link represents the fact that, in general, individuals are more disposed (i.e. intend) to engage in positively valued behaviour that are believed to be achievable.

Research indicates that there may be individual differences in the weights placed on the different components, with some individuals tending to base their intentions on attitudes and others on norms across behaviours. In addition, in situations where (for example) attitudes are strong, or where normative influences are powerful, PBC may be less predictive of intentions.

Determinants of attitudes

An attitude is a function of salient behavioural beliefs, which represent perceived consequences or other attributes of the behaviour. Following expectancy-value conceptualizations, consequences are composed of the multiplicative combination of the perceived likelihood that performance of the behaviour will lead to a particular outcome and the evaluation of that outcome.

A = ∑i=1

i=p

bi·ei (3)

bi is the behavioural belief that performing the behaviour leads to some consequence i (thus, bi is the subjective probability that the behaviour has the consequence i). ei is the evaluation of consequence i, and p is the number of salient consequences over which this values are summed.

Fishbein (1993) claims equation 3 is not a model of process but is a computational representation aimed to capture the output of a process that occurs automatically as a function of learning. This part of the model, the relationship between attitudes and beliefs is based on Fishbein´s summative model of attitudes. It is assumed that a person may possess a large number of beliefs about a particular behaviour, but that at any one time only some of these are likely to be salient. It is the salient beliefs which are assumed to determine a person´s attitude.

Determinants of subjective norm

Subjective norm is a function of normative beliefs, which represent perceptions of specific significant other´s preferences about whether one should or should not engage in behaviour, multiplied by the person´s motivation to comply with that referent´s expectation.

SN = ∑j=1

j=q

nbj·mcj (4)

It should be noted that the distinction between behavioural beliefs and normative beliefs is somewhat arbitrary, and there is often considerable correlation between the two.

Determinants of perceived behavioural control

Judgements of perceived behavioural control are influenced by beliefs concerning whether one has access to the necessary resources and opportunities to perform the behaviour successfully, weighted by the perceived power of each factor. The perceptions of factors likely to facilitate or inhibit the performance of the behaviour are referred to as control beliefs. These factors include both internal (information, personal deficiencies, skills, abilities,

Behavioural Beliefs

Normative Beliefs

Control Beliefs

Attitude

Subjective norm

PBC

Intention Behaviour

Actual Behavioural control

External variablesDemographic (age, sex, occupation, socioeconomic status, religion, education)

Personality traits (extraversion, agreeableness, conscientiousness, neuroticism, openness)

Enviromental influences (access, physical environment)

emotions) and external (opportunities, dependence on others, barriers) control factors. Ajzen (1991) has suggested that each control factor is weighted by its perceived power to facilitate or inhibit performance of the behaviour.

PBC = ∑k=1

k=r

ck·pk (5)

Commentary

Behaviour is determined by intention to engage in the behaviour and perceptions of control over performance of the behaviour.Intention is determined by attitude towards the behaviour, subjective norms and perceived behavioural controlAttitude is determined by perceptions of the likelihood of salient outcomes and their evaluation. Subjective norm is determined by normative beliefs and motivation to comply with salient referents.PBC is determined by the perceived presence or absence of requisite resources and opportunities and the perceived power of these factors to facilitate or inhibit performance of the behaviour. Actual control influences the impact of PBC on intention and behaviour.

3-. Summary of research

Key issues raised in reviews of the TPB

The majority of studies have demonstrated that the background factors influence intentions and behaviour indirectly by their effects on behavioural, normative or control beliefs. One common criticism of the TRA/TPB has been that it assumes that all behaviour is rational and fails to take account of other non-cognitive or irrational determinants of human behaviour. This criticism highlights potential problems with the way in which typical TRA/TPB studies are conducted. In particular, differences may exist between the contemplation of a behaviour (e.g. when filling in a TPB questionnaire) and its actual performance in a real-life context. It may be particularly difficult for individuals to correctly anticipate the strong emotions that drive their

behaviour in real life. This would lead to problems with incorporating emotional factors within typical TRA/TPB applications.

4-. Developments

Multiple component view of the TPB

Components of intentions:

Intentions capture the motivational factors that influence behaviour, how hard people are willing to try, how much effort they would exert to perform the behaviour or the self-instructions individuals give themselves to act. Warshaw and Davis (1985) made the distinction between measures of behavioural intentions and self-predictions. Sheppard et al´s (1988) meta-analysis indicated the latter to be more predictive of behaviour. Beyond this, Bagozzi (1992) has suggested that attitudes may first be translated into desires which then develop into intentions to act, which direct action. The meta-analysis of Armitage and Conner found that intentions and self-predictions were stronger predictors of behaviour than desires when PBC was included as a predictor. Ajzen and Fishbein (2005) also argue that willingness to perform behaviour, personal norm with respect to the behaviour or identification with the behaviour are each closely related to intention.

Components of attitudes:

In the TRA/TPB attitudes towards behaviours are measured by semantic differential scales. However, research on attitudes towards objects has used such measures to distinguish between affective and cognitive measures of attitudes, with the suggestion that the former are more closely related to behaviour. It is now recognized that similar components of an attitude towards a behaviour can be distinguished in the TRA/TPB. In particular, it has been noted that an attitude may contain instrumental (e.g. desirable-undesirable, valuable-worthless) as well as experiential or affective (e.g. Pleasant-unpleasant, interesting-boring) aspects.

This is problematic because some research has indicated that intentions may be more closely related to affective than cognitive measures of attitudes. Ajzen and Fishbein (2005) indicated that appropriate attitude measures for use in the TPB should contain items representing the instrumental and affective or experiential components of attitudes. The two components do tend to be correlated with one another but can be discriminated based on their underlying belief systems, their different functions and empirical differences. However, in order to maintain the parsimony of the TPB is has also been suggested that it is useful to distinguish between a higher order construct of attitude and these differentiated components of attitude at a lower order. Thus, in relation to instrumental and experiential attitudes, a higher order construct of attitude is invoked to explain the shared variance between these two components.

Two forms of such models have been recently proposed. In the first, the higher order constructs are “caused” by their lower order components. In the second, it is the higher order construct which “causes” the lower order components.

In the TRA/TPB attitudes are held to be determined by underlying salient behavioural beliefs. It is assumed that a person may possess a large number of beliefs about a particular behaviour, but that at any one time only some of these are likely to be salient. It is the salient beliefs which are assumed to determine a person´s attitude.

Towriss (1984) noted that while the theory would suggest the use of individually salient beliefs, respondents are normally presented with modal salient beliefs based on pilot work. This procedure has a number of disadvantages. First, procedures for sampling “behavioural beliefs” about specific behaviours may sample an excessively cognitive subset (i.e. Instrumental beliefs) of the influences that actually play on people´s attitudes, and fail to elicit beliefs which are more difficult to articulate (affective or moral influences), yet potentially important influences on attitude formations. A second problem is that the TPB is primarily concerned with individuals ‘beliefs. The supplying of beliefs by researcher may not adequately capture the beliefs salient to the individual. Another problem related to the use of modal beliefs concerns the relative importance of beliefs. A number of authors have suggested that the prediction of attitudes might be improved by adding a measure of importance or relevance of the attribute to the attitude towards the behaviour. (population stratified by key beliefs).

Components of norms:

Armitage and Conner (2001) noted that subjective norms were the weakest predictor of intentions in the TPB. Similarly , Sheppard et al (1988) and Van den Putte (1991) noted that subjective norms were weak predictors of intentions across the TRA.

However, at least partly, this appeared to be attributable to the use of single item measures with lower reliability. Where studies employed reliable multi-item measures subjective norms were significantly stronger predictors of intentions, although still weaker than attitudes or PBC. Another explanation of the weak predictive power of normative measures in the TRA/TPB is the conceptualization of norms used. Cialdini et al (1991) call the normative beliefs used in the TRA/TPB injunctive social norms as they concern the social approval of others which motivates action through social reward/punishment, and distinguish them from descriptive social norms which describe perceptions of what others do.

Most recently, Fishbein (1993) and Ajzen and Fishbein (2005) suggested that both subjective norms and descriptive norms be considered indicators of the same underlying concept, social pressure. Similarly to attitudes one might conceive of social pressure as a higher order factor with injunctive and descriptive norms lower order measures. However, it is unclear whether a formative model with injunctive and descriptive norms producing overall social pressure or a reflective model with social pressure producing injunctive and descriptive norms is more appropriate.

A further distinction in relation to the normative component of the TPB has been made by researchers applying a social identity theory/self-categorization approach. For example, Terry

and Hogg (1996) demonstrated that group norm measures were more predictive of intentions when they employed a measure of group identification (e.g. I identify with my friends with regard to smoking”) rather than motivation to comply. Group norms have been operationalized as either what members of the group are perceived to do (e.g. “Most of my friends smoke”; i.e. Descriptive norms) or to think (i.e. “Most of my friends think smoking is a good thing to do”, sometimes referred to as group attitude). Studies using this approach tend to report interactive effects between group norms and group identification rather than main effects.

In particular, for referent groups not defined by the behaviour an interactive model between group attitude (or descriptive norm) and group identification may be appropriate.

There has also been a work examining normative beliefs. It should be noted that the distinction between behavioural beliefs and normative beliefs is somewhat arbitrary, and there is often found to be considerable correlation between the two. However, there is some merit in maintaining a distinction between the determinant of behaviour that are attributes of the person and those which are attributes of the social environment.

Other researchers have suggested that rather than the way normative influences is tapped; it is measurement of compliance with this pressure which needs attention. There has been debate about the most appropriate level of specificity to use in the wording of the motivation to comply item. For example, should motivation to comply be in general, specifying a group of behaviour or be specific to the behaviour in question (the principle of compatibility might suggest this last alternative?). Alternatively, as we noted earlier in relation to social identity theory, a measure of group identification rather than motivation to comply might be more appropriate.

Components of PBC:

The difference between the TRA and the TPB lies in the control component (i.e. PBC) of the TPB. Meta-analytic evidence has generally supported the power of PBC to explain additional variance in intentions and behaviour after controlling for the component of the TRA. The overlap in definition of PBC with Bandura´s definition of self-efficacy is striking. Ajzen (1991) argued that the PBC and self-efficacy constructs were synonymous and more recently “quite similar”. There is controversy surrounding the nature and measurement of PBC which has a number of threats. A first thread concerns disparities in the definitions and operationalizations used with respect to PBC and the possibility that it represents a multidimensional construct. A second threat has questioned the discriminant validity of some operationalizations of the PBC as distinct from other components of the TPB.

Early definitions of the PBC construct were intended to encompass perceptions of factors that were both internal (e.g. Knowledge, skills, willpower) and external (e.g. time availability, cooperation of others) to the individual.

The items used to tap PBC included both perceptions of difficulty and perceptions of control over the behaviour. In the majority of early applications of the TPB studies tended to employ “mixed” measures of PBC that included both components. However, more recently opinion

appears to have coalesced around the idea of PBC being a multidimensional construct consisting of two separate but related components. In particular, Ajzen argues that PBC can be considered as a second-order construct that consists of two components which he labels perceived self-efficacy and perceived controllability.

Self-efficacy component of PBC, Ajzen has suggested that this component can be tapped by two types of items: first, the perceived difficulty of the behaviour; second, the perceived confidence the individual has to perform the behaviour.

A second threat to research with the PBC construct has focused on discriminant validity. Fishbeing and colleagues note two problems with employing perceived difficulty items to tap PBC: first, there is no necessary association between individual´s perceptions of how difficult a behaviour is held to be and how much they perceive control over performing it; second, easy-difficult items overlap conceptually and empirically with semantic differential items designed to tap affective attitudes.

This review of existing research suggests at least three possibilities in relation to measuring PBC within the TPB. First, the use of formative research within a behavioural domain can result in the appropriate selection of items with a unidimensional structure. Second, measures can explicitly tap the two components of PBC identified by Ajzen: perceived self-efficacy and perceived controllability. Third, measures of PBC could be selected which explicitly avoid perceived difficulty items because of concerns about overlap with affective attitudes. Another issue in relation to the PBC component of the TPB is the assessment of underlying control beliefs. These beliefs are assumed to be based upon various forms of previous experience with the behaviour. Control beliefs are tapped by items assessing the frequency with which a facilitator or inhibitor of the behaviour occurs, e.g. “I can climb in an area that has good weather”(likely-unlikely) weighted by its perceived power to facilitate or inhibit performance of the behaviour, e.g “Good weather makes mountain climbing...”(easier-more difficult) with both items scored as bipolar items.

Additional predictors

A number of additional constructs to be added have been suggested, we consider four additional constructs:

1-. Anticipated regret:

The traditional method for eliciting behavioural beliefs may fail to elicit affective outcomes associated with performance of the behaviour. Such anticipated affective reactions to the performance or non-performance of a behaviour may be important determinants of attitudes and intentions, especially in situations where the consequences of the behaviour are unpleasant or negatively affectively laden. Anticipated regret is a negative, cognitive-based emotion that is experienced when we realize or imagine that the present situation could have been better had we acted differently. Studies have demonstrated that regret is distinct from other component of the TPB. For regret to be further considered as an additional predictor of intentions we need research demonstrating independent effects for anticipated regret when controlling for both instrumental and experiential attitudes.

2-. Moral norms:

Cialdini et al (1991) distinguished between injunctive, descriptive and moral norms. The first two might usefully be considered components of a social norms construct. The latter are the individual´s perception of the moral correctness or incorrectness of performing a behaviour and take account of “...personal feeling of...responsibility to perform, or refuse to perform, a certain behaviour”. Moral norms might be expected to have an important influence on the performance of those behaviours with a moral or ethical dimension. Ajzen suggested that moral norms work in parallel with attitudes, subjective norms and PBC, and directly influence intentions. These findings imply that moral norm would be a useful addition to the TPB, at least for those behaviours where moral considerations are likely to be important.

3-. Self-identity:

It may be defined as the salient part of an actor´s self which relates to a particular behaviour. It reflects the extent to which an actor sees him or herself fulfilling the criteria for any societal role. Ajzen and Fishbein (2005) suggest self-identity might be best considered as an alternative measure of intentions.

4-. Past behaviours:

It is argued that many behaviours are determined by one´s previous behaviour rather than cognitions such as described in the TRA/TPB (Sutton 1994). The argument is based on the results of a number of studies showing past behaviour to be the best predictor for future behaviour. What is of particular interest is the contribution of past behaviour to the predictions of intentions and behaviour once the TPB variables are taken into account. Despite the strong effects of pas behaviour within the TPB we should be cautious in giving past behaviour the same status as other predictors in the TPB. It is clear that past behaviour cannot be used to explain future performance of an action (i.e. individuals do not perform a behaviour because they have performed in the past), although habit may be one way of conceptualizing this effect (Sutton 1994).

5-. Operationalization of the Model

The present text provides (a) some examples of measures applied to somewhat different behaviours within a common theme, and (b) the variation between research studies in the level of specificity and in adherence to the Target, Action, Context, Time (TACT) principle.

Behaviour:

Developing a clear conceptualization of the behaviour or behavioural categories we wish to predict. The principle of compatibility indicates that measures of behaviours and components of the TPB need to be formulated at the same level of specificity with regard to action, target, context and time. Specification of the action, target, context and time frame for the behaviour will greatly assist the specification of the TPB measures. Assessment of such a behaviour might involve simple self-reports or whether the behaviour was performed in the specified context over the appropriate time period (in this example, behaviour is assessed on the following day):

I walked for an hour in the countryside yesterday.Definitely did not 1 2 3 4 5 6 7 Definitely did

The reliability of self-report measures may be expected to vary as a function of the behaviour and context in question.Behavioural intention:

I intend to exercise at X health club at least four times each week during the next two weeks. Definitely do 1 2 3 4 5 6 7 Definitely do not

I make an effort to exercise at X health club at least four times each week during the next two weeks. Definitely do 1 2 3 4 5 6 7 Definitely do not

I try to exercise at X health club at least four times each week during the next two weeks.Definitely do 1 2 3 4 5 6 7 Definitely do not

Multiple-item measures are more appropriate than single-item measures because of increased reliability.

Attitudes:

Attitudes are a person´s evaluation of the target behaviour and are typically measured by using items such as:

My taking regular physical activity over the next 6 months would be:

Harmful 1 2 3 4 5 6 7 Beneficial Unpleasant 1 2 3 4 5 6 7 Pleasant Unenjoyable 1 2 3 4 5 6 7 Enjoyable Bad 1 2 3 4 5 6 7 Good Foolish 1 2 3 4 5 6 7 Wise

Semantic differential.Ajzen (2002c) has suggested that steps be taken to ensure that both instrumental (e.g. worthless-valuable; harmful-beneficial; unimportant-important) and experiential (e.g. unpleasant-pleasant; unenjoyable-enjoyable; unsatisfying-satisfying) items should be included within attitude measures. Measurement of instrumental and experiential components of attitudes allows the analysis of the lower and higher order components of attitudes.Alternatively, attitudes may be assessed by simply asking the respondent more direct questions about their attitudes:

My attitude towards my exercising at X health club is:

Extremely unfavourable 1 2 3 4 5 6 7 Extremely favourable Extremely negative 1 2 3 4 5 6 7 Extremely positive

Subjective norm

Early described as a “person´s...perception that most people who are important to him think he should or should not perform the behaviour in question” and a “person´s perception of the social pressures put on him to perform or not the behaviour in question”. There is a difference in these two definitions but the construct has traditionally been operationalized as the person´s subjective judgement concerning whether significant others would want him or her to perform the behaviour or not, using items such as:

Most people that are important to me think I:Should 1 2 3 4 5 6 7 Should not

take regular physical activity over the next 6 months

There are number of well known problems with the use of single items and additional items have been suggested to make a multi-item scale, although there is little reliability data on such measures:

People who are important to me would:Should 1 2 3 4 5 6 7 Should not

of my taking regular physical activity over the next 6 monthsMost people who are important to me want me to take regular physical activity over the next 6 months Should 1 2 3 4 5 6 7 Should not

Most recently it has been suggested that measures of subjective norm should include both injunctive normative influences (such as those given above which reflect significant others think the person should do) and descriptive normative influences (such the items that reflect what significant others are perceived to do with respect to the behaviour in question):

Most of my friends exercise regularly:Strongly disagree 1 2 3 4 5 6 7 Strongly agree

Most of my family members exercise regularly: Strongly disagree 1 2 3 4 5 6 7 Strongly agree

Measurement of injunctive and descriptive norm components of subjective norms would allow the analysis of lower and higher order components of norms.

Perceived behavioural control

PBC represents the overall control the individual perceives him or herself to have over performance of the behaviour:

How much control do you have over whether you exercise for at least 20 minutes, three times per week for the next fortnight?

No control 1 2 3 4 5 6 7 Complete controlI feel incomplete control of whether I exercise for at least 20 minutes, three times per week for the next fortnight.

Strongly disagree 1 2 3 4 5 6 7 Strongly agree

For me to exercise for at least 20 minutes, three times per week for the next fortnight will be:Very easy 1 2 3 4 5 6 7 Very difficult

I am confident that I can I exercise for at least 20 minutes, three times per week for the next fortnight:Strongly disagree 1 2 3 4 5 6 7 Strongly agree

The internal reliability of PBC items has frequently been found to be low, such that separate assessment of controllability (the first two items above) and self-efficacy (the second two items above) is now recommended. Measurement of controllability and self-efficacy components would allow the analysis of the lower and higher order components of PBC.

Problem of adequate measurement?

Depending on how people conceptualize the notion of “control” and the notion of “difficulty”.People may consider the performance of a behaviour to be “under their control” yet at the same time consider it to be difficult to carry out. Mixing unipolar and bipolar scales among PBC items may contribute to this problem.

Behavioural beliefs

In the TRA/TPB the relevant behavioural beliefs are those salient to the individual. However, most applications of these models employ modal salient beliefs derived from pilot studies.

Examples of belief strength and outcome evaluation items:

Belief strength assesses the subjective probability that a particular outcome will be a consequence of performing the behaviour. Outcome evaluations assess the overall evaluation of that outcome and are generally treated as bipolar and responded to on “bad-good” response formats. Belief strength and outcome evaluation are then multiplicatively combined and summed (equation 3) to give an indirect measure of attitude. The problem with such calculations with interval data has been noted by a number of authors, although no completely satisfactory solution has been found.

Belief strength:

My taking regular physical activity would make me feel healthier.Unlikely 1 2 3 4 5 6 7 Likely

My taking regular physical activity would make me lose weight.Unlikely 1 2 3 4 5 6 7 Likely

Outcome evaluation:Feeling healthier would be... Bad 1 2 3 4 5 6 7 GoodLosing weight would be... Bad 1 2 3 4 5 6 7 Good

Normative beliefsAs with behavioural beliefs, most studies employ modal rather than individually salient referent groups. Ajzen and Fishbein (1980) suggest that we ask about the groups or individuals

who would approve or disapprove of you performing the behaviour or who come to mind when thinking about the target behaviour. The most frequently mentioned (modal) referents are then incorporated in the final questionnaire. Typically two to six referent groups are included. Normative beliefs are a person´s perceptions of whether specific referents would want him or her to perform the behaviour under considerations. Motivation to comply is operationalized as the person´s willingness to comply with the expectations of the specific referents. The relevant normative belies and motivations to comply are then multiplicatively combined and summed (equation 4) to give an indirect measure of normative pressure.

Normative belief strength:

My friends think I should take regular physical activity.Unlikely 1 2 3 4 5 6 7 Likely

Health experts think I should take regular physical activity.Unlikely 1 2 3 4 5 6 7 Likely

Motivation to comply:

With regard to physical activity, I want to do what my friends think I should doStrongly agree 1 2 3 4 5 6 7 Strongly disagree

With regard to physical activity, I want to do what health experts think I should do Strongly agree 1 2 3 4 5 6 7 Strongly disagree

Control beliefs

Other studies have also used modal control beliefs derived from pilot studies. Ajzen and Driver (1992) suggests that individuals are asked to list the factors and conditions that make it easy or difficult to performs the target behaviour and the most frequently mentioned (modal) items are used in the final questionnaire. Control beliefs assess the presence or absence of facilitating or inhibiting factors are commonly scored on “never-frequently”, “false-true”, “unavailable-available”, or “Unlikely-likely” response formats. Perceived power items assess the power of the item to facilitate or inhibit performance of the behaviour. The relevant items are then multiplicatively combined and summed (equation 5) to give an indirect measure of the perceived behavioural control.

Control Beliefs:I have free time... Never 1 2 3 4 5 6 7 FrequentlyI am near sports facilities... Never 1 2 3 4 5 6 7 Frequently

Power:Having free time makes taking regular physical activity.

Less likely 1 2 3 4 5 6 7 More LikelyBeing near sports facilities makes taking regular physical activity. Less likely 1 2 3 4 5 6 7 More Likely

6-. Behavioural intentions

Generally speaking, there are two stages involved in using the TPB to develop an intervention. First, it is important to determine which variables should be targeted. Second, the message content must be identified. There are some main problems with interpreting these findings, first, many studies did not conduct an initial TPB study to identify appropriate target of intervention. Second, many studies did not test the effectiveness of interventions in changing targeted cognitions before examining impacts on intentions and behaviour.

What then should we make of the role of the TPB in behavioural change interventions? The theory of planned behaviour can provide general guideline...but it does not tell us what kind of intervention will be most effective. Thus, for example, the popularity of the Elaboration Likelihood Model as a model of persuasion could be used to supplement the TPB in intervention work.

There is evidence which indicates that a change in people´s beliefs can bring about changes in attitudes, intentions and/or behaviour lends some support to the basic causal sequence at the heart of the TPB. Objective behaviour measures are often difficult to obtain and the reliability of self-report measures merits critical scrutiny. What the TPB does offer is a theory of volitional behaviour which posits an explicit causal relationship between people´s beliefs and their subsequent actions. It is thus apparent that changes in those beliefs will lead to behavioural changes, all other things being held equal.

In relation to theory development the key issue is the light that intervention studies can throw on supposed causal relationships in the TPB. For such an aim, experimental designs which allow a focused manipulation of one construct and observation of the effects on other constructs are required.

7-. Future directions

Moderator variables: The role of moderator variables within TPB (i.e. variables that influence the magnitude of relationships between TPB constructs). A range of moderator variables have been examined in relation to the TPB. These can be broadly split into additional variables and properties of components of the TPB. The former include anticipated regret, moral norms and past behaviour. The latter include accessibility, direct experience, involvement, certainty, ambivalence, affective-cognitive consistency and temporal stability (to obtain accurate prediction of behaviour, intentions...must remain reasonably stable over time until the behaviour is performed”).

Conclusion:

In the broad social environment there will be a number of influences on people´s health and on their behaviour: any of these that do not impinge on people´s perceptions of control will not be accessible to analysis via the TPB. Health behaviours need to be understood not only in terms of people´s beliefs, values, perceived social pressure and perceived control but also in terms of the individual´s behaviour history and the broader social pressures that may be operating. While the TPB is concerned with proximal psychological influences on behaviour, we have to recognize the broader social structure within which these influences develop.