A systematic review of effort discounting research in humans: Current knowledge, recommendations, and future directions

Effort is a ubiquitous feature in the decision-making literature. Increasing numbers of studies examine the effect of effort requirements on behavior using a discounting framework, assessing the process by which the subjective value of an outcome decreases as the effort required to obtain it increases. Therefore, a review of methodological approaches, findings, and issues is timely. Accordingly, in this systematic review, we identified research studies examining effort discounting to explore how choice architecture factors used in delay discounting and other experimental manipulations affected effort discounting, and the mathematical descriptors used to summarize the relationship between subjective value and effort requirements. Our analysis suggests an area ripe for future research and identifies important knowledge gaps. These gaps are attributable to the use of divergent definitions of effort, as well as highly heterogeneous methodologies, which limit our ability to generate strong conclusions about the intersection between effort and delay discounting processes.