# Pupil dynamics reveal preparatory processes in the generation of pro-saccades and anti-saccades in open skill sports athletes

## TL;DR

The study shows that pupil size can reveal how athletes prepare for quick eye movements, indicating better cognitive control and efficiency compared to non-athletes.

## Contribution

The study introduces pupil dynamics as a novel physiological index for evaluating cognitive load and arousal in sports contexts.

## Key findings

- Athletes showed reduced pupil dilation compared to non-athletes during task preparation.
- Larger pupil dilation and smaller tonic pupil size were linked to faster saccade reaction times.
- Pupil dilation correlated with saccade peak velocity but not endpoint accuracy.

## Abstract

This study investigated pupil dynamics to establish a physiological index of mental processes associated with executive functioning, enabling objective evaluation of cognitive load during training to improve understanding of cognitive control in sport-specific contexts. Using video-based eye-tracking, we examined pupil and saccade responses in athletes (N = 40) and non-athletes (N = 40) performing an interleaved prosaccade and anti-saccade task. In this task, participants were instructed prior to target appearance to either make a reflexive saccade toward the target (pro-saccade) or inhibit that response and generate a voluntary saccade in the opposite direction (anti-saccade). Larger pupil dilation prior to target onset was observed during anti-saccade compared to pro-saccade preparation (p < 0.001, ηp2 = 0.153). Athletes showed reduced pupil dilation compared to non-athletes (p < 0.05, ηp2 = 0.049). In addition, trials with larger pupil dilation and smaller tonic pupil sizes were associated with faster saccade reaction times. Pupil dilation also positively correlated with saccade peak velocities but showed no association with saccade endpoint accuracy. These findings suggest that athletes may engage in more efficient motor preparation, as reflected by reduced pupil dilation. Moreover, phasic pupil dilation, indexing cognitive load, and tonic pupil size, associated with arousal level, both contributed to the control of saccade dynamics during goal-directed movements. Together, these results highlight the utility of pupil size as an objective and informative index for assessing both cognitive and arousal functions in sports science research.