Although it is not always reflected in the discourse of contemporary psychology, the most proximal determinants of human behavior lie in
experience. It is the manner in which people interpret events and the perceived relations of those events to the actors' psychological needs that provide the
regnant causes of intentional actions (Ryan & Deci, 2004). In sum, it is typically people's feelings, beliefs, motives, and goals, and the perceived environment within which these feelings, beliefs, motives, and goals arise, that organize subsequent behavior. Yet oddly empirical psychology today still often finds suspect, or actively discounts, the importance of "subjective" phenomenon, when it is precisely subjective phenomenon that the discipline of psychology ought to lawfully explain. Self determination theory (SDT) has at its core the concept of basic, universal psychological needs for competence, autonomy, and relatedness. Unlike most other theories that use the concept of psychological needs to assess individual differences in motive strength, SDT proposes that these basic needs represent the necessary nutriments for healthy, full functioning. Thus, SDT specifies that these needs must be satisfied for individuals to experience optimal psychological development, performance, and well-being within any domain and across cultural contexts. As it has developed, SDT has used the concept of basic psychological needs to integrate a wide range of phenomena that have been encompassed by SDT's four mini-theories; namely, cognitive evaluation theory, organismic integration theory, causality orientations theory, and basic psychological needs theory. Moreover, the concept of basic psychological needs has been useful in extending SDT to a variety of new research areas, including subjective energy, mindfulness, and close relationships. Finally, the concept of needs has proven to be practically useful, as shown by SDT's applications in far-ranging domains: education, parenting, work, medicine, sport and exercise, politics, aging, and psychotherapy. SDT, in short, has aimed at providing a fuller understanding of what it is that people truly need for optimal living, and all that distracts from, or undermines, those needs being fulfilled. (PsycINFO Database Record (c) 2012 APA, all rights reserved)