Researchers at Meta Reality Labs have tested eye tracking against traditional head tracking with controllers to asses UI/UX efficiencies with some interesting results.
Eye tracking interactions were evaluated using an eye tracking enabled Meta Quest 2 VR headset with 30 participants. Each participant went through 1098 targets using multiple conditions representative of AR/VR targeting and selecting tasks, including both traditional standards and those more aligned with AR/VR interactions today. The researchers circular white world-locked targets, and an eye tracking system with sub-1-degree mean accuracy errors running at approximately 90Hz.
In a targeting and button press selection task, the researchers compared completely unadjusted, cursor-less, eye tracking with controller and head tracking, which both had cursors. Across all inputs, the particpants were presented targets in a configuration similar to the ISO 9241-9 reciprocal selection task and another format with targets more evenly distributed near the center. ISO 9241-9 sets out the design requirements for non-keyboard input devices, addressing the needs of the fifth to ninety-fifth percentile of the population with design recommendations to accommodate the anthropometric (related to the measurements and proportions of the human body) characteristics of the population.
Targets were laid out either flat on a plane or tangent to a sphere and rotated toward the user. Eye tracking outperformed the head by 27.9% and performed comparably to the controller (5.63% decrease) in throughput. Eye tracking had improved subjective ratings relative to head in ease of use, adoption, and fatigue (66.4%, 89.8%, and 116.1% improvements, respectively) and had similar ratings relative to the controller (reduction by 4.2%, 8.9%, and 5.2% respectively). Eye tracking had a higher miss percentage than controller and head (17.3% vs 4.7% vs 7.2% respectively). The researchers believe the results of this baseline study are a strong indicator that eye tracking, with even minor sensible interaction design modifications, has tremendous potential in reshaping interactions in next-generation AR/VR head mounted displays.
It’s worth noting that the term subjective is an apt description of the results because the results were based on questionnaires, and you would need a body of research that performed the same evaluations to find a statistically meaningful pattern of data. On the other hand, the researchers do show that eye tracking has a baseline value that suggests it will become more effective, and more widely adopted, as an input method for AR and VR headsets. The test carried out were not done using a user interface that was specifically designed for eye tracking which means that there’s room to improve on the efficiency of eye tracking input methods with better user interface design.
Reference
A. S. Fernandes, T. S. Murdison and M. J. Proulx, “Leveling the Playing Field: A Comparative Reevaluation of Unmodified Eye Tracking as an Input and Interaction Modality for VR,” in IEEE Transactions on Visualization and Computer Graphics, doi: 10.1109/TVCG.2023.3247058
