Looking in Depth: Targeting by Eye and Controller Input for Multi-Depth Target Placement

We explored how interaction performance is affected by multi-depth VR targeting and button selection using two targeting methods: eye tracking with no UX modifications and feedback, or the controller with a visible cursor for targeting. Selections happened on a controller button press for both targeting modalities. Targets had a diameter of either 3, 4, or 5 degrees, placed in depths between 0.3 m-5m. When comparing conditions of a 1 m single depth vs. multi-depth environment, the eyes were less affected by depth than the controller. We found that performance decreased in multi-depth scenarios on targeting and selection for the controller as measured by Throughput (22% decrease), Movement Time (31% increase), and Misses (66% increase). Depth also affected eye tracking significantly, but to a lesser degree, for Throughput (4% decrease) and Movement Time (6% increase) but not Misses (5% increase). The eyes outperformed the controller in multi-depth scenarios, as measured by Throughput (2.86 bits/s vs. 2.56 bits/s), and were similar in Movement Time (1.10s vs. 1.10s) but had the most Misses (21% vs. 9%). Our study also shows that selecting consecutive targets that come closer to the user is more difficult than those that diverge away from the user, and that targets with larger depth distances take longer to select. Overall, this study provides further supporting evidence that eye tracking can play an important role in 3D interactions.