Abstract: Cognitive effort investment is a core decision-making process in which individuals dynamically allocate limited mental resources through cost-benefit trade-offs. Traditional research has primarily explained the generation and variation of effort from the perspective of objective task difficulty, yet accumulating evidence suggests that subjective experiences play a driving role in effort investment independently of objective factors. Following the framework of “objective difficulty – subjective experience – individual difference moderation”, the present review systematically synthesizes the theoretical and empirical process in the field of cognitive effort. First, it distinguishes theories concerning the origins of subjective cost, such as the opportunity-cost account and recent related developments, from theories of effort-allocation mechanisms, such as Motivational Intensity Theory and the Expected Value of Control theory. Second, it examines the boundary conditions and measurement limitations of objective task difficulty as a driver of effort investment, and introduces difficulty-calibration approaches based on individual ability. Third, it analyzes the independent contributions, interrelations, and cross-trial dynamics of three subjective dimensions: perceived difficulty, perceived effort, and emotional experience. On this basis, the review proposes a testable dual-path integration hypothesis, according to which Need for Cognition and growth mindset may moderate the dynamic influence of objective and subjective factors on effort investment through value evaluation and attributional interpretation, respectively. Finally, in response to current limitations such as confounded indicators and unclear mechanisms, the review outlines future directions including systematic dissociation of objective and subjective effects, multimodal assessment frameworks, and broader application contexts.

Key words: cognitive effort, subjective experience, objective difficulty, need for cognition, growth mindset.