Self-Determination Theory (SDT) is an empirically based, organismic and humanistic theory of human motivation and personality development. The theory originally developed in the 1980s by Edward Deci and Richard Ryan and since then has been developed and researched all around the world.
The theory focuses on people's inherent growth tendencies and innate psychological needs and differentiates between types of motivation along a continuum from controlled to autonomous. SDT stress the role of the social-contextual factors as supporting or thwarting people's psychological needs and growth tendencies.
Ryan, R. M., & Deci, E. L. (2017). Self-Determination Theory. Basic psychological needs in motivation, development, and wellness. New York-London: The Guilford Press.