Pupil Response in Visual Tracking Tasks: The Impacts of Task Load, Familiarity, and Gaze Position

Abstract

Pupil size is a significant biosignal for human behavior monitoring and can reveal much underlying information. This study explored the effects of task load, task familiarity, and gaze position on pupil response during learning a visual tracking task. We hypothesized that pupil size would increase with task load, up to a certain level before decreasing, decrease with task familiarity, and increase more when focusing on areas preceding the target than other areas. Fifteen participants were recruited for an arrow tracking learning task with incremental task load. Pupil size data were collected using a Tobii Pro Nano eye tracker. A 2 × 3 × 5 three-way factorial repeated measures ANOVA was conducted using R (version 4.2.1) to evaluate the main and interactive effects of key variables on adjusted pupil size. The association between individuals’ cognitive load, assessed by NASA-TLX, and pupil size was further analyzed using a linear mixed-effect model. We found that task repetition resulted in a reduction in pupil size; however, this effect was found to diminish as the task load increased. The main effect of task load approached statistical significance, but different trends were observed in trial 1 and trial 2. No significant difference in pupil size was detected among the three gaze positions. The relationship between pupil size and cognitive load overall followed an inverted U curve. Our study showed how pupil size changes as a function of task load, task familiarity, and gaze scanning. This finding provides sensory evidence that could improve educational outcomes.

Early Eye Disengagement Is Regulated by Task Complexity and Task Repetition in Visual Tracking Task

“…The repeated trials might also reduce the uncertainty about moving trajectories, which would facilitate the anticipation of the upcoming path before the arrow (target). Moreover, these results are supported by previous findings on EEDT in surgical settings, in which experienced surgeons performed more EEDT [8,13].…”

“…Prior to the experiment, each participant provided informed written consent. This study utilized the same experimental setting as our prior work [13], with both projects stemming from the same research initiative and using the same group of participants' eye-tracking datasets. While the previous publication focused on aspects of pupil variation, the current analysis focuses on a different aspect of EEDT, a gaze-based eye movement.…”