FUNCTIONAL-SIGNIFICANCE OF PSYCHOLOGICAL VARIABLES THAT ARE INCLUDED IN THE THEORY OF PLANNED BEHAVIOR - A SELF-DETERMINATION THEORY APPROACH TO THE STUDY OF ATTITUDES, SUBJECTIVE NORMS, PERCEPTIONS OF CONTROLAND INTENTIONS

The Theory of Planned Behaviour was proposed by Ajzen (1985) in an att empt to expand the applicability of the Theory of Reasoned Action (TRA ) to situations where behaviour is not under complete volitional contr ol. However, recent research does not address the issue of the stabili ty of intentions, yet this is considered a boundary condition of the T RA on theoretical grounds. Therefore, the purposes of the present arti cle were, first, to make a theoretical approach to the study of the st ability of behavioural intentions by discussing assumptions underlying self-determination theory. Second, because, according to self-determi nation theory (Deci & Ryan, 1985), stability of intentions is related to the functional significance of psychological events, investigation of the functional significance of attitudes, subjective norms and perc eived behavioural control was attempted through a study dealing with l eisure-time physical activity. Because investigation of functional sig nificance requires instruments assessing behavioral regulations, instr ument development took place. Results partially supported the validity of behavioural regulations with respect to leisure-time physical acti vity. Furthermore, subjective norms were found to represent only the c ontrolling dimension of functional significance. Attitudes and perceiv ed behavioural control were found to represent both the controlling an d informational dimensions of functional significance. Results are dis cussed in relation to assumptions underlying the Theories of Reasoned Action and Planned Behaviour and the Theory of Trying. Implications fo r theory development are made. (C) 1998 John Wiley & Sons, Ltd.