The cognitive and motor determinants of the perception of effort.

Effort refers to the physical work or force exerted to achieve an outcome, which is dissociable from the subjective experience that accompanies this exertion, termed perceived effort. Previous decision-making studies have examined effort valuation, focussing on individual differences in effort and reward sensitivity when choosing an action. These studies measure anticipatory aspects effort and reward, rather than their experiential aspects. Yet, how individuals perceive effort has significant implications for mental health. Here, we address this gap using an effort psychophysics task in young, healthy adults (n = 76). Participants used a hand dynamometer to raise a visual "mercury" column to a target zone, aiming to match the required force for at least 3 s within a 7-s window to succeed. After each trial, participants rated their perceived effort on a 0-100 visual analogue scale. We estimated the contribution of force and task failure to perceived effort ratings using a robust regression model. Higher depressive symptoms were associated with a reduced influence of exerted force and an increased influence of task outcome (failure) on perceived effort. We identified additional key cognitive and motor contributors to the experience of effort, such as accumulated fatigue, expectations and force stability. The experience of effort thus arises from multiple interacting cognitive and motor contributors. Individual differences in the contribution of these factors to the experience of effort, such as force and failure are associated with depressive symptoms, underscoring the importance of considering experiential aspects of effort in mental health research.