Theory of Planned Behavior

TPB added to TRA because TRA components may not be sufficient to explain behavior in which volitional control is reduced

  • Behavior
  • Perceived behavioral control
  • Control beliefs
  • Perceived power

Perceived behavioral control

Definition(s):

    • The extent to which a person feels able to enact the behavior
    • A function of an individual's control beliefs and perceived power with beliefs

Example:

    • Prospective study concerning exercise among pregnant women, baseline question: "For me to exercise during my second trimester of pregnancy will be"
    • Followed by a 7 point extremely difficult / extremely easy response scale

Control beliefs

Definition(s):

    • Beliefs about the presence of factors that may facilitate or impede performance of the behavior
    • Contributes to perceived behavioral control along with perceived power

Example:

    • Prospective study concerning exercise among pregnant women, baseline question: "If I wanted to, I can easily exercise during my second trimester of pregnancy"
    • Followed by a 7 point strongly agree / strongly disagree response scale

Perceived power

Definition(s):

    • Beliefs about the power of situational and internal factors to inhibit or facilitate the performing of the behavior
    • Contributes to perceived behavioral control along with control beliefs

Example:

    • Prospective study concerning exercise among pregnant women, baseline question: "How much control do you have over exercising during your second trimester of pregnancy?"
    • Followed by a 7 point very little control / complete control response scale