Predicting cognitive effort: role of mental energy, performance
feedback, arithmetic skill, and caffeine
Abstract
Effortful behavior sustains family life, makes careers, and improves
mental health. Effort is a motivational construct that is typically
distinguished from physical and mental energy in diagnostic systems.
However, overlapping neural substrates pertaining to the dopamine system
tie these constructs together. To shed light on this conflict, here we
assessed the individual contributions of mental energy, performance
feedback, arithmetic skill, and caffeine to effortful decision-making in
a novel, low-cost, high-throughput behavioral task that we designed to
measure known dopaminergic functions. In this task, participants chose
to expend high or low cognitive effort, solving arithmetic questions in
working memory, while taking into account the size of reward associated
with each choice, and also the likelihood of winning the reward. We
found that individuals high in mental energy chose to expend high
cognitive effort when the reward probability was high, but that low
energy individuals made fewer high effort choices even when the rewards
were likely. High energy individuals prioritized feedback from high
effort tasks, whereas low energy individuals responded to feedback from
low effort tasks. Arithmetic accuracy, a reward contingency, was
predicted by an index of arithmetic skill and caffeine consumption.
Shared variances between mental energy, arithmetic accuracy, and
cognitive effort point to overlapping substrates. Insights gained have
important implications for job and academic environments in which mental
effort is key to success.