Abstract

Motivation science has gained increasing academic attention, emerging as a distinct field at the intersection of cognitive psychology and economics, particularly incentive theory. Beyond academia, motivation research has practical implications for self-regulation, mental health, and performance quality. While rewards or penalties drive many actions, some activities require no external incentives—they are pursued spontaneously and enjoyed for their own sake. Scholars explain this phenomenon differently: some argue that the goal of such actions is inherently tied to their execution, while others suggest they fulfil fundamental psychological needs. In this article, we explore intrinsic motivation by analyzing two key theories: self-determination theory (SDT) and the means-ends fusion model (MEF). Despite their different approaches – one focusing on activity content and the other on structure – we argue that they are complementary. We then examine the overjustification effect, which occurs when offering a reward for performance diminishes, rather than enhances, a person’s interest in the activity. By integrating insights from SDT, MEF, and behavioral decision-making, we propose an original explanation of this phenomenon. Finally, we discuss practical applications, particularly in education, and suggest ways to balance intrinsic motivation and external incentives to support long-term engagement and performance.