Disambiguating distal target selection in dense and occluded virtual environments has been a challenge for Virtual Reality (VR) interaction design. While raycasting is a widely used interaction technique for selecting distant objects, it defaults to the first intersected target, forcing users into disambiguation phases, which can disrupt presence, increase cognitive load, and slow interaction. We introduce VoiceRay, a voice-based target selection that allows users to specify the ordinal position of the intended target along the ray (e.g., “second object”) without altering the scene or requiring additional inputs from the user. In a study with 24 participants, VoiceRay was compared against five existing techniques: AlphaCursor, LassoGrid, RayCursor, BubbleRay, and Raycasting. Results showed that VoiceRay significantly decreased selection time, maintained presence, increased usability, and reduced cognitive load. These findings demonstrate that voice-based interaction offers an effective, easy-to-use alternative for resolving 3D selection ambiguity in dense and occluded VR environments.

In 3D environments, designing efficient notifications is crucial for capturing user attention. While visual notifications -such as objectattached and fixed-position ones- are commonly used in virtual environments, they often require users to shift their gaze away from task-relevant areas, which can interrupt workflow and delay responses. To address these limitations, we designed two gaze-based notification techniques to provide responsive and intuitive notification in a virtual reality (VR) cooking task. We evaluated four different notification types: two world-fixed notifications (onObject and onDock) and two gaze-based methods (GazeCue and Gaze+Dock) with 16 participants. Our results show that participants performed better in using gaze-based notifications compared to world-fixed ones. Questionnaire results indicated higher usability, greater perceived presence, and lower cognitive load for gaze-based notifications. These results highlight the effectiveness of gaze-based notification techniques in VR by reducing the need for visual search and minimizing cognitive load. Our findings provide insights for developers or engineers to design more intuitive and responsive user-interfaces for 3D environments.

Hand visualization significantly impacts user performance in virtual reality (VR), particularly in tasks requiring precise finger movements. Common hand avatar visualizations, such as opaque or transparent, often occlude critical elements or distract users, potentially reducing accuracy. To address this issue, we investigated adaptive hand visibility techniques, which vary the hand avatar visibility based on the current movement sub-task aiming to enhance user performance. We evaluated these techniques on a VR-based Pedicle Screw Placement task with 15 participants. Each participant inserted virtual screws into a spine using five hand visualization conditions: opaque, transparent, invisible, speed-based visibility (hand visibility changes with hand speed), and position-based visibility (hand visibility adapts to the proximity of critical elements). Results showed that speed-based and position-based visualizations significantly improved accuracy, usability, and overall performance compared to traditional methods. The widely adopted opaque visualization yielded the lowest accuracy and usability. Our findings emphasize the benefits of adaptive hand visualization based on sub-tasks, recommending its implementation in VR applications to increase usability and user accuracy.

Visual guides help to align strokes and raise accuracy in Virtual Reality (VR) sketching tools. Automatic guides that appear at relevant sketching areas are convenient to have for a seamless sketching with a guide. We explore guides that exploit eye-tracking to render them adaptive to the user’s visual attention. EyeGuide and EyeConGuide cause visual grid fragments to appear spatially close to the user’s intended sketches, based on the information of the user’s eye-gaze direction and the 3D position of the hand. Here we evaluated the techniques in two user studies across simple and complex sketching objectives in VR. The results show that gaze-based guides have a positive effect on sketching accuracy, perceived usability and preference over manual activation in the tested tasks. Our research contributes to integrating gaze-contingent techniques for assistive guides and presents important insights into multimodal design applications in VR.

When working in Virtual Reality (VR), the user’s performance is affected by how the user holds the input device (e.g., controller), typically using either a precision or a power grip. Previous work examined these grip styles for 3D pointing at targets at different depths in peripersonal space and found that participants had a lower error rate with the precision grip but identified no difference in movement speed, throughput, or interaction with target depth. Yet, this previous experiment was potentially affected by tracking differences between devices. This paper reports an experiment that partially replicates and extends the previous study by evaluating the effect of grip style on the 3D selection of nearby targets with the same device. Furthermore, our experiment re-investigates the effect of the vergence-accommodation conflict (VAC) present in current stereo displays on 3D pointing in peripersonal space. Our results show that grip style significantly affects user performance. We hope that our results are useful for researchers and designers when creating virtual environments.

The vergence-accommodation conflict (VAC) limits user performance in current Virtual Reality (VR) systems. In this paper, we investigate the effects of the VAC in a single-focal VR system using three experimental conditions: with no VAC, with a constant VAC, and with a varying VAC. Previous work in this area had yielded conflicting results, so we decided to re-investigate this issue. Eighteen participants performed an ISO 9241:411 task in a study that closely replicates previous work, except that the angle of the task space was rotated 20 degrees downward, to make the task less fatiguing to perform, which addresses a potential confound in previous work. We found that the varying VAC condition had worse performance than the other conditions, which indicates that the contrasting results in previous work were very likely due to biomechanical factors. We hope that our work contributes to the understanding of the influence of the VAC in VR systems and potential strategies for improving user experience and performance in immersive virtual environments.