Gaze behaviour during multiple object tracking is dependent on binocular vision integrity

Despite the critical importance of binocular vision integrity in daily activities, there exists limited understanding of how alterations in binocular vision integrity impact gaze behaviour during dynamic, complex psychomotor skills. This study aimed to measure how alterations in binocular vision integrity, created by Bangerter filters (BF), affect gaze behaviour during multiple object tracking (MOT).

During the experiment, 22 volunteers completed the MOT task under three different visual conditions. The first condition involved natural binocular viewing, while the second and third conditions used 0.4 and 0.2 neutral density BF, respectively, resulting in monocular blur in the sensorially dominant eye. During the MOT task, participants were instructed to track three of eight balls for 10 s, and the speed was adjusted using a staircase procedure. Throughout the task, the following gaze parameters were recorded: fixation duration, saccade duration, amplitude and frequency as well as blink rate.

During MOT execution, participants employed three gaze strategies regardless of viewing conditions: saccadic movements were predominant, followed by maintaining fixation on a central location throughout the trial and to a lesser extent, smooth pursuit eye movements. There was a significant effect of manipulating viewing conditions on the MOT scores (p = 0.046, η²  = 0.09). As the viewing conditions became more difficult, we observed a decrease in fixation duration (p = 0.004, η²  = 0.16) and blink rate (p < 0.001, η²  = 0.20) and an increase in saccadic amplitude (p < 0.001, η²  = 0.29).

The results support the notion that perceptual-cognitive skills depend on the integrity of binocular vision, underscoring the sensitivity of gaze behaviours to any impairment of binocular function.