Self-Determination Theory (SDT), formulated by Richard Ryan and Edward Deci, explains that human motivation is driven by three fundamental psychological needs: autonomy, competence, and relatedness. When these needs are met, individuals experience personal growth, intrinsic motivation, and overall well-being.

Autonomy is the need to feel in control of one's actions and decisions. For example, a student who chooses their research topic is likely to be more engaged and motivated than one who is assigned a topic. Autonomy fosters intrinsic motivation because individuals feel they act out of personal choice rather than under external pressure.

Competence is the need to feel capable and effective when facing challenges. A software engineer might feel motivated when solving complex coding problems, as the sense of mastery reinforces their confidence and skill development. When people feel competent, they are more likely to take on new challenges and invest in tasks that promote growth.

Relatedness refers to the need to connect and feel a sense of belonging. Employees are more motivated and satisfied in the workplace when they feel supported by colleagues and supervisors. This sense of belonging enhances emotional well-being and fosters collaboration.

SDT emphasizes that intrinsic motivation (engaging in activities for their inherent satisfaction) flourishes when these three needs are met. For instance, athletes who feel autonomous, competent, and connected to their fellow players are more likely to enjoy their sport and perform better than athletes who are solely driven by external rewards (e.g., money, fame). Conversely, when these needs are unmet, individuals may shift toward extrinsic motivation, focusing on external rewards like money or approval.

Research has demonstrated the universality of SDT, showing that across cultures, people who satisfy their needs for autonomy, competence, and relatedness report higher levels of happiness, personal growth, and well-being.