Abstract
An organism’s behavioral success is determined by its ability to mobilize resources to overcome challenges. This ability involves the noradrenergic system, indicated by the finding that pupil-size increases proportionally with currently exerted effort. However, humans can deliberate in advance whether to engage in effort in the future. It remains unclear how effort is represented in such an anticipatory fashion during decision-making. We investigated this by measuring pupil responses while participants decided whether to accept or reject rewards that required effort execution after the experiment. We found a faster rate of pupillary dilation in decisions to accept high-effort rewards. This was accompanied by stronger fMRI activity in anterior cingulate cortex (ACC) and anterior insula: When accepting high-effort rewards, individuals with faster pupil dilation showed larger activity in these areas. Our results identify a brain process instantiating anticipatory arousal when humans prepare for a physical challenge, potentially reflecting simulated energization.