Theory of Planned Behaviour
Extension of TRA (prediction of behaviour)
- theory that links one’s beliefs and behaviour
- suggests that people are much more likely to intend to enact certain behaviours when they feel that they can enact them successfully
- states that attitude, subjective norms, and perceived behavioural control, together shape an individual’s behavioural intentions and behaviours
- developed from Theory of Reasoned action (to improve power of this by adding perceived behavioural control)
- includes perceived behavioural control (TRA does not)
- TPB applied to studies of the relations among beliefs, attitudes & behavioural intentions
- in various fields like advertising, public relations, healthcare, sport management & sustainability
perceived behavioural control PBC
determinant of BI
self-efficacy & controllability
- the individuals perception of the extent of control that he/she has over the performance of the behaviour
self-efficacy
level of difficulty that is required to perform the behaviour
- or one’s belief in their own ability to succeed in performing the behaviour
controllability
the outside factors, and one’s belief that they personally have control over the performance of behaviour or if it is controlled by externally uncontrollable factors
–> high perceived behavioural control increases individual’s confidence in being capable of performing a specific behaviour
Theory of Reasoned Action
includes 2 key Determinants:
- behavioural intentions
- subjective norms
Principles of compatibility - any behaviour consists of
- action
- target
- context
- Time
–> restricted to prediction of volitional behaviour
Application of TPB
- protection behaviours (like sexual behaviours)
- risk behaviours: alcohol, substance use
- detection behaviours: physical activity
Function of TPB
B= w1BI+w2PBC
B: behaviour
BI: Behavioural intention
w1+w2: regression weights
Determinants of Behavioural Intention (BI)
Attitude
Subjective Norms (SN)
Perceived behavioural control PBC
Attitude (determinant of BI)
a learned disposition to respond in a consistently favourable or unfavourable manner with respect to an object
Subjective Norms (SN)
a persons beliefs of whether significant others think he/she should engage in the behaviour
Additional predictors to TPB
- components of intention: how much effort a person exerts
- components of attitudes: affective vs cognitive
- components of norms: injunctive (or prescriptive norm, how one should behave) vs descriptive (how most people usually behave)
- components of PBC: external (e.g. time cooperation with others) and internal (e.g. knowledge, skills, willpower)
4 more predictors:
- anticipated affective reactions (e.g. anticipated regret)
- moral norms
- self-identity
- past behaviour (e.g. experiences)
Belief integrated in TPB
- Behavioural beliefs ((dis)advantages of behaviour)
- normative beliefs (other people/groups to come to mind when thinking about behaviour, what do they think about the behaviour?)
- control beliefs (easy or difficult to perform behaviour)
behavioural beliefs
characteristics, qualities, attributes of object of the specific behaviour
(e.g. what do you see as pros and cons of behaviour x?)
normative beliefs
beliefs of what other people/groups would approve/disapprove when thinking about executing target behaviour
(e.g. are there any groups or people who come to mind when thinking about behaviour X?)
control beliefs
factors and conditions that facilitate or prevent to perform target behaviour
(e.g. what factors might prevent or help you to go jogging regularly?)
Integrated Behavioural Model IBM
extension of TRA & TPB
- as in these models, most important determinant of behaviour is INTENTION to perform the behaviour
IBM 4 other components that directly affect behaviour
- knowledge and skill
- no/few environmental contraints
- saliency (of behaviour)
- experience/habit of performing behaviour
Weaknesses of TRA (Sniehotta et al.)
- common-sense proportions not open to empirical falsification
- limited predictive validity (TPB)
- theory does not fully account for the variance in intentions
- TPB has an exclusive focus on rational reasoning
- TPB fails to provide an adequate basis for behavioural change interventions
- lack of support for the effectiveness of behaviour change interventions based on TPB
- retirement of TPB & alternative theoretical approach
TRA & TPB (Monatno article)
- focus on theoretical constructs concerned with individual motivational factors as determinants of the likelihood of performing specific behaviours
assumption:
best predictor of behaviour is intention (determined by attitudes & norms)
important components:
attitude + subjective norm + behavioural intention (=TRA) + Perceived Behavioural Control (TPB)
Behaviour Change Method
Interventions with help of TPB
Matrix of change objectives
- standardised method of combining & documenting all this information
- rows: performance objectives (sub-behaviours)
- columns: determinants
- in each cell: beliefs are listed for corresponding determinant/performance objective combination
What to change?
Interventions with help of TPB
- what behaviours do we want to change?
- -> they are influenced by environmental agents (teachers, parents, politicians)
- -> have set of preparatory sub-behaviours = performance objectives of an intervention
- -> achieving all performance objectives = effective intervention
e.g. if adolescent buys condoms, but does not carry them when needed, likelihood of safe intercourse is low → intervention should promote/address communication about
condoms instead of highlighting only advantages
How to identify what to change on the first place
interventions with help of TPB
- systematic reviews
- -> compile the available empirical evidence - interviews
- -> interview target population in qualitative study to find sub-behaviours and increased likelihood of effectivity of intervention - Survey (Quantitative data)
- -> conduct a survey in order to determine the relative importance od behavioural determinants & underlying beliefs
Intervention Characteristics
3 key features
- theoretical basis of the intervention (theory)
- behaviour change methods used (strategies to promote behavioural intentions)
- mode of delivery (2 aspects)
- intervention format: one-on-one or group basis
- source of the intervention: delivered by expert or non-expert
Characteristics of successful interventions
most successful in generating intention & behaviour change of treatment:
a) is based on protection motivation theory or the TRA/TPB
b) uses social encouragement & incentives for behaving or remaining in the program
c) is delivered by a health educator or research assistant
