the theory. Limitations Although the scope of TRA is wide, the theory still has its limitations and like any other theory, needs constant refinement and revision particularly when extending to choice and goals. The distinction between a goal intention and a behavioral intention concerns the capability to achieve one's intention, which involves multiple variables thus creating great uncertainty. Ajzen acknowledged that "some behaviors are more likely to present problems of controls than others, but we can never be absolutely certain that we will be in a position to carry out our intentions. Viewed in this light it becomes clear that strictly speaking every intention is a goal whose attainment is subject to some degree of uncertainty." According to Eagly and Chaiken, TRA does not take into account that certain conditions that enable the performance of a behavior are not available to individuals. Since the TRA focuses on behaviors that people decisively enact, the theory is limited in terms of being able to predict behaviors that require access to certain opportunities, skills, conditions, and/or resources. Additionally, certain intentions do not necessarily play a role in terms of connecting attitudes and behavior. According to a study conducted by Bagozzi and Yi, the performance of a behavior is not always preceded by a strong intent. In fact, attitudes and behaviors may not always be linked by intentions, particularly when the behavior does not require much cognitive effort. Development and investigation In 1979, H. C. Triandis proposed expanding TRA to include more components. These factors were habit, facilitating conditions, and affect. When a person performs a behavior in a routine manner they form a habit. Facilitating conditions are conditions that make completion of an action more or less difficult. Both of these conditions affect their behavior directly. On the other hand, affect is the emotional response a person has towards a behavior and this emotional response only affects behavioral intention rather than directly affecting behavior. This expanded version of TRA has been used to study behaviors like women's participation in mammography procedures. In 1985, Ajzen extended TRA to what he refers as the theory of planned behavior (TPB). This involves the addition of one major predictor—perceived behavioral control. This addition was introduced to account for times when people have the intention to conduct the behavior, but the actual behavior is thwarted because of subjective and objective reasons. In the theory of planned behavior, the