Vikram Chib PhD.
Department of Biomedical Engineering
Johns Hopkins Medical Institutes
Kennedy Krieger Institute
“Subjective Valuation of Effort”
Our decisions are shaped not only by the rewards at stake, but also the effort required to obtain them. Moreover, the subjectivity of effort plays an integral role in driving choice – if a task feels very effortful one may not be willing to perform the work required to obtain reward, whereas if a task feels less effortful one may be more likely to persevere. Despite the ubiquity of such effort-based judgments in our daily lives, subjective valuation of effort has received limited investigation. In this talk I will present functional brain imaging data that was obtained while human subjects made decisions under uncertainty about prospective effort. Participants exhibited subjectivity in their decision-making, displaying increased sensitivity to changes in subjective effort as objective effort levels increased. Analysis of blood-oxygenation level dependent (BOLD) activity revealed that signals in the prefrontal cortex encoded the subjective valuation of prospective effort, and that fatigue induced changes in an individual’s physical state served to alter these representations. Furthermore, we found that functional connectivity between premotor cortex and prefrontal cortex was decreased in individuals that found effort to be especially costly, indicative of a mechanism by which motor cortical state served to modulate brain regions involved in effort-based choice. Taken together, these results provide new insights into the behavioral and neural mechanisms responsible for decision-making regarding effort.