“…While considerable experimental evidence linking locus coeruleus activity and pupil size has been reported (de Gee et al, ; Joshi et al, ; Murphy, O'Connell, O'Sullivan, Robertson, & Balsters, ; Rajkowski, Kubiak, & Aston‐Jones, ; Reimer et al, ; Varazzani et al, ), however, it is also possible that the cholinergic system exerts control over pupil size in visuo‐motor tasks (McGinley et al, ; Naber, Frässle, et al, ; Naber et al, ; Nelson & Mooney, ; Nieuwenhuis, de Geus, & Aston‐Jones, ; Reimer et al, ; Vinck et al, ). Changes in pupil size in response to task difficulty or explorative behavior in visual and auditory paradigms have previously been attributed to processes in the cholinergic, parasympathetic pathway including the Edinger‐Westphal nucleus rather than the adrenergic, sympathetic pathway (Steinhauer, Siegle, Condray, & Pless, ; Wang et al, ). Importantly, we also recently demonstrated that administration of choline supplementation, which likely boosts systemic cholinergic availability, both decreases resting pupil size and changes behavior toward a greater emphasis on accuracy rather than speed on precisely the same motor aiming task used presently (Naber et al, ).…”