PREPRINT_From-Pupil-to-Performance_DoekemeijerCabooter

Response inhibition is key to flexible behavior, and while its mechanistic process dynamics are increasingly better understood, there are indications for important neuromodulatory influences that are thus far mostly considered in animal and pharmaceutical work. Specifically, such work has indicated a tight link between response inhibition and norepinephrine (NE) levels in the brain. In the present work, we used pre-trial pupil measures as established proxies of tonic NE levels to investigate the link with response inhibition using the stop-signal task. We did so in two healthy student samples, one performing in a standard stop-signal task, and one in a variant in which half of the experiment, stop-signals were to be ignored. Our results showed that (1) (faster) GoRT was predicted by (larger) pretrial pupil measures, which was stronger in the stop context induced by the standard stop-signal task; (2) (lower) stopping success was predicted by (larger) pretrial pupil measures, which may be explained by a faster go response working against successful inhibition; (3) (shorter) stop-signal reaction times (SSRT) were also associated with (larger) pretrial pupil measures, but somewhat less consistently. Taken together, our findings show a clear pattern that pre-trial pupil measures predict response speed on go trials, in particular in a stopping context, and a slightly less clear relationship with measures of response inhibition. Our results therefore support a link between fluctuating tonic NE levels and the process dynamics in response inhibition, but in a fashion that is less exclusive to core inhibition processes than might have been expected.