Anticipatory energization revealed by pupil and brain activity guides human effort-based decision making

Abstract

17An organism's behavioral success is determined by its ability to mobilize resources to overcome 18 challenges. This ability involves the noradrenergic system, indicated by the finding that pupil-size 19 increases proportionally with currently exerted effort. However, humans can deliberate in advance 20 whether to engage in effort in the future. It remains unclear how effort is represented in such an 21 anticipatory fashion during decision-making. We investigated this by measuring pupil responses while 22 participants decided whether to accept or reject rewards that required effort execution after the 23 experiment. We found a faster rate of pupillary dilation in decisions to accept high-effort rewards. This 24 was accompanied by stronger fMRI activity in anterior cingulate cortex (ACC) and anterior insula: When 25 accepting high-effort rewards, individuals with faster pupil dilation showed larger activity in these areas. 26Our results identify a brain process instantiating anticipatory arousal when humans prepare for a 27 physical challenge, potentially reflecting simulated energization. 28 30 31Should I go to the gym tonight or should I skip training? The ability to select actions by considering their 32 costs and benefits is crucial for survival in most animals 1 . Relatively unique to humans, however, is 33 the remarkable ability to take such choices in a purely anticipatory fashion, deciding about potential 34 future actions for which the potential benefits and costs are out of sight 2 . This ability is important for 35 planning as it allows us to deliberate for sequences of actions whether the effort of overcoming all 36 subsequent costs will be worth the associated rewards. 37Indeed, humans constantly simulate future rewards to make decisions. Cues associated with 38 reward trigger more vivid imagination of future events than neutral ones do 3 . There is also evidence 39 that we make better decisions by thinking about future events so vividly as if we were experiencing the 40 pleasure of the imagined rewards 4,5 . A decision to go to the gym might result from a mental simulation 41 of rewarding experiences such as the thrill from getting yelled at by that energetic spinning instructor 42 or the relaxing shower after the workout. Overwhelming evidence shows that both experienced and 43 anticipated rewards are signalled by activity in the dopaminergic (DA) system 6 , which also comprises 44 the core brain reward circuitry including the ventral striatum and ventromedial prefrontal cortex (vmPFC 45 7 ). These reward signals are thought to reflect learned associations between reward cues and 46 reinforcers 6 . But what is remarkable from this wealth of research is the consensus that DA not only 47 signals experienced but also purely anticipated rewards, confirming its pivotal role in decision making. 48By contrast, very little is known about how simulation of physical effort could guide choice. Here 49 two possible scenarios have been proposed. First, a prevailing idea from the effort discounting literature...

Learning progress mediates the link between cognitive effort and task engagement

“…Importantly, the current study tested the relationship between task difficulty and pupil size during a cue period and not during task performance. As such, pupil size tracked the average accuracy of the upcoming task, consistent with previous accounts (Kurniawan, Grueschow & Ruff, 2021) which dissociated the time of effort anticipation from that of effort exertion in an instrumental effort paradigm and showed that pupil size tracked the anticipation of the upcoming effort level of the task in a voluntary choice paradigm. Moreover, these increases in pupil dilation were stronger when the participants accepted to exert the effort option versus not, suggesting that pupil size might be associated with the energization required to perform an upcoming action.…”

Pupil dilation predicts individual success in emotion regulation and dietary self-control

“…pupil constriction in response to brightness changes, whereas the sympathetic pathway controls dilation in response to arousal (Loewenfeld, 1958). Arousal could for example be caused by emotionally salient stimuli, but also be recruited in order to meet cognitive demands (Aston-Jones & Cohen, 2005;Eldar, Cohen, & Niv, 2013, 2016Mather, Clewett, Sakaki, & Harley, 2016;Verguts & Notebaert, 2009) or in order to mobilize effort (Kurniawan, Grueschow, & Ruff, 2020;Varazzani et al, 2015;Walton & Bouret, 2019). Previous studies have also reported that pupil diameter increases when individuals regulate their emotions (Johnstone, van Reekum, Urry, Kalin, & Davidson, 2007;Kinner et al, 2017;Richey et al, 2015;Urry, 2009;Urry et al, 2006;.…”