Behavioural Models

THE THEORY OF PLANNED BEHAVIOUR

            The theory of planned behaviour (TPB) started as the theory of reasoned action in 1980 to predict an individual’s intention to engage in a behaviour at a specific time and place. The theory was intended to explain all behaviours over which
people have the ability to exert self-control. The key component to this model is behaviour intent; behaviour intentions are influenced by the likelihood that the behaviour will have the expected outcome and the subjective evaluation of the risks and benefits of that outcome.

            The TPB has been used successfully to predict and explain a wide range of health behaviours and intentions including smoking, drinking, health services utilization, breastfeeding, and substance use, among others. The theory of planned behaviour states that behavioural achievements depends on both motivation (intention) and ability (behavioural control). It distinguishes between three types of beliefs: behavioural; normative; and control. TPB comprises of six constructs that collectively represents a person’s actual control over behaviour.

     1.      Attitude: This refers to the degree to which a person has a favourable and un-favourable evaluation of the behaviour of interest. It entails a consideration of the outcomes of performing the behaviour.

    2.      Behavioural intention: This refers to the motivational factor that influences a given behaviour where the stronger the intention to perform the behaviour, the more likely the behaviour will be performed.

    3.      Subjective norms: This refers to the belief whether most people approve or disapprove of the behaviour. It relates to a person’s beliefs about whether peers and people of importance to the person think he or she should engage in the behaviour.

     4.      Social norms: This refers to the customary codes of behaviour in a group or people or a larger cultural context. Social norms are considered normative, or standard, in a group of people.

     5.      Perceived power: This refers to the perceived presence of factors that may facilitate or impede performance of behaviour. Perceived power contributes to a person’s perceived behavioural control over each of those factors.

    6.      Perceived behavioural control: This refers to a person’s perception of the ease or difficulty of performing the behaviour of interest. Perceived behavioural control varies across situations and actions, which results in a person having varying perceptions of behavioural control depending on the situation. This construct of the theory was added later, and created the shift from the theory of reasoned action to the theory of planned behaviour.

LIMITATION OF THE THEORY OF PLANNED ACTION

            There are several limitations of this theory, and it includes the following:

1.      It assumes the person has acquired the opportunities and resources to be successful I performing the desired behaviour, regardless of the intention.

2.      It does not account for other variables that affects behavioural intention, such as fear, threat, mood or past experience.

3.      While it does consider normative influence, it still does not take into account environmental or economic factors that may influences a person’s intention to perform a behaviour.

4.      It assumes behaviour is the result of linear decision making process, and does not consider that it can change over time.

5.      While the added construct of perceived behavioural control was an important addition to the theory, it doesn’t say anything about the actual control over behaviour.

6.      The time frame between the “intent” and “behavioural action” is not addressed by the theory.

The theory of planned behaviour has shown more utility in public health than the health belief model, but it is still limiting in its inability to consider environmental and economic influence. Over the past several years, researches have used some constructs of the TPB and added other components from behavioural theory to make it a more integrated model. This has been in response tom some of the limitations o0t theory of planned behaviour in addressing public health problems.

REFERENCE

Modules/DB/SB721-Models/SB721-Models3.html

THE THEORY OF REASONED ACTION

The theory of reasoned action is a model for the prediction of behavioural intention spanning predictions of attitude and predictions of behaviour. The subsequent separation of behavioural intention from behaviour allows for explanation of limiting factors on attitudinal influence (Ajzen, 1980). This theory was developed by Martin Fishbein and Icek Ajzen (1975, 1980), derived from the previous research that started out as the theory of attitude, which led to the study of attitude and behaviour.

The theory of reasoned action, derived from a psychological setting, basically has three componential construct which are:

      1.      Behavioural intention (BI)

      2.      Attitude (A)

      3.      Subjective norm (SN)

The theory suggests that a person’s behavioural intention depends on the person’s attitude about the behaviour and subjective norms (BI = A + SN). That is if a person intends to do a behaviour then it is likely that the person will do it.

Accordingly, behavioural intention measures a person’s relative strength of intention to perform a behaviour while attitude consist of the beliefs about the consequences of performing the behaviour multiplied by his or her evaluation of these consequences (Fishbein & Ajzen 1975) and subjective norms is seen as a combination of perceived expectations from relevant individuals or groups along with the intention to comply with these expectations. In a simple term, a person’s volitional behaviour is predicted on how he thinks other people would view him if he performed the behaviour. A person’s attitude combined with subjective norms forms his behavioural intention.

PROCESS

As a process, an expanded theory of reasoned action [TRA] flow model can be expressed as follows:

LIMITATIONS AND EXTENSION

   1.   Goals versus behaviours: Distinction between a goal intention [an ultimate accomplishment such as losing 10 pounds] and a behavioural intention [taking a diet pill].

    2.     Choice among alternatives: The presence of choice may dramatically change the nature of the intention formation process and the role of the intentions in the performances of behaviour.

     3.      Intention versus estimates: there are certain times when what one intends to do and what one actually expects are different.

             With this Sheppard et al. (1988) concluded that the model has strong predictive utility, even when utilized to investigate situations that do not fall within the boundary conditions originally specified for the model. That is not to say, however, that further modifications and refinements are unnecessary, especially when the model is extended to goal and choice domains. Hence in its review and modification process, it has been extended by Ajzen himself into the theory of planned behaviour (TPB).

REFERENCES

·        Ajzen, I., Albarracin, D., & Hornik, R. (2007). Prediction and change of health behaviour: Applying the theory of reasoned action approach. Mahwah, NJ: Lawrence Erlbaum.

·        Ajzen, I. & Fishbein, M. (1980). Understanding attitudes and predicting social behaviour. Englewood Cliffs, NJ: prentice-Hall.

·        FIshbein, M. & Ajzen, I. (1975). Belief attitude, intention, and behaviour: An introduction to theiry and reaearch. Reading, MA: Addison-Wesley.

·        Sheppard, B.H.; Hartwick, J. & Warshaw, P.R (1988). The theory of reasoned action: A meta-analysis of past research with recommendations for modifications and future research. Journal of Consumer Research, 15, 325-343.