Experimental resources for the following paper: https://link.springer.com/article/10.3758/s13423-023-02283-5 Our senses adjust in order to fulfill perceptual needs. Previous studies showed a benefit of large (dilated) pupils for peripheral detection, and a benefit of small (constricted) pupils for foveal discrimination. Thus, one of the questions that arises is whether pupil size changes as a function of the focus of attention, which is smaller when attention is focused centrally, and larger when attention is diffusely distributed over the peripheral vision; that is, does the attentional breadth affect the size of the pupil? Even though some attempts were made to answer this question by manipulating attentional breadth, none of these studies simultaneously controlled for all potential confounds. In this study we aim to test the same prediction that pupil size increases with increased attentional breadth while carefully controlling for all potential confounds. To that aim, we focus on how pupil size changes as a function of the eccentricity of a to-be-attended stimulus. The experiment employs a visual discrimination task in which participants are presented with a rapidly presented stream of noise patches arranged into three concentric rings. Crucially, these rings occupy various eccentricities, such that a ‘near eccentricity’ ring is centered around the fixation dot, surrounded by a ‘medium eccentricity’ ring, which is in turn surrounded by a ‘far eccentricity’ ring. The target is either an increment or decrement of luminance, presented at a random location within one of the three rings; participants report whether the target is a luminance increment or decrement. Before the target appeared, a cue indicated at which of the rings the target is the most likely (80% validity) to appear. Participants covertly attended the cued ring while fixating a dot at the middle of the screen. We hypothesize that pupil size should increase with increasing cue eccentricity. This open science framework repository contains a study preregistration, the experiment, the data, and the analysis scripts.