The most recent addition was that of a third factor, perceived behavioral control. Perceived behavioral control refers to the degree to which a person believes that he or she can perform a given behavior. Perceived behavioral control involves the perception of the individual's own ability to perform the behavior. In other words, perceived behavioral control is behavior- or goal-specific. That perception varies by environmental circumstances and the behavior involved. The theory of planned behavior suggests that people are much more likely to intend to enact certain behaviors when they feel that they can enact them successfully.