Health Behaviour and Behaviour change 2

Theory of Reasoned Action (TRA) (Fishbein, 1967)

  • Core Constructs:

    • Subjective Norms: The perceived social pressure to engage or not engage in a behavior.

    • Beliefs: An individual's beliefs about the outcomes of the behavior.

    • Behavioral Intention: The likelihood of an individual performing a behavior, which is shaped by subjective norms and attitudes.

Theory of Planned Behavior (TPB) (Ajzen, 1985)

  • Expansion of TRA: Introduces Perceived Behavioral Control to account for the influence of external factors.

  • Key Constructs:

    • Attitude Toward the Behavior: Personal evaluation of the behavior's outcomes (pros and cons).

    • Subjective Norms: Social influence or perceived expectations from significant others.

    • Perceived Behavioral Control (PBC): The perceived ease or difficulty of performing the behavior, which accounts for external factors that may hinder or facilitate action.

    • Behavioral Intention: The intention to engage in the behavior, which mediates between beliefs and actual behavior.

  • Questions to Guide TPB Constructs:

    • What do I believe about the behavior (attitude)?

    • What would significant others think of me doing it (subjective norm)?

    • Is it feasible for me to do it (perceived behavioral control)?

    • How strong is my intention to do it?

  • Pros and Cons:

    • Pros: Parsimonious, incorporates measurable constructs, supported by evidence (e.g., McEachan et al., 2011).

    • Cons: Does not address environmental factors, assumes rational behavior, based on self-report data with potential errors, intention does not always lead to behavior (intention-behavior gap, Armitage & Conner, 2001).

Transtheoretical Model (TTM) or Stages of Change Model (Prochaska & DiClemente, 1984)

  • Core Idea: Change occurs in stages, and people may cycle through these stages multiple times before achieving permanent change.

  • Stages:

    1. Precontemplation: No intention to change within the next 6 months.

    2. Contemplation: Aware of the behavior and considering change within the next 6 months.

    3. Preparation (Determination): Ready to act within the next 30 days, planning steps to change.

    4. Action: Actively changing behavior and modifying habits.

    5. Maintenance: Sustained behavior change for over 6 months.

    6. Termination: No desire to return to old behaviors; behavior change is now permanent.

    7. Relapse: Return to previous behaviors; may involve recycling through earlier stages.

  • Key Concepts:

    • Decisional Balance: Weighing the pros and cons of change varies depending on the stage.

    • Stage-Matched Interventions: Tailoring interventions to match the individual's current stage can improve outcomes (e.g., smoking cessation).

  • Strengths:

    • Intuitive and easy to understand.

    • Effective in clinical settings, especially for addictions and behavioral changes.

  • Criticisms:

    • Lacks Social Context: Does not consider external social influences, such as drinking for social reasons (Marks et al., 2000).

    • Stage Classification: Not everyone fits into distinct stages (Budd & Rollnick, 1996).

    • Inconsistent Evidence: Limited and mixed evidence on effectiveness for substance use changes (Sutton, 2001).

Comparison and Use:

  • TRA is more suitable for analyzing intentions and the immediate factors affecting behavior but does not include external control factors.

  • TPB improves upon TRA by adding Perceived Behavioral Control, which is critical when there are barriers to behavior change (e.g., accessibility issues, skills).

  • TTM is useful for understanding behavior change as a process and tailoring interventions to the individual's readiness to change.