Self-determination theory (SDT) is a theory of motivation developed by Edward Deci and Richard Ryan that focuses on supporting innate psychological needs for competence, autonomy and relatedness. SDT posits that these basic needs must be satisfied for people to experience optimal motivation and development, and that social and environmental factors can either support or thwart need satisfaction. According to SDT, when these needs are fulfilled people become self-determined to pursue and persist in activities out of interest or intrinsic motivation.