A Virtual Reality Application of the Rubber Hand Illusion Induced by Ultrasonic Mid-Air Haptic Stimulation

Ultrasonic mid-air haptic technologies, which provide haptic feedback through airwaves produced using ultrasound, could be employed to investigate the sense of body ownership and immersion in virtual reality (VR) by inducing the virtual hand illusion (VHI). Ultrasonic mid-air haptic perception has solely been investigated for glabrous (hairless) skin, which has higher tactile sensitivity than hairy skin. In contrast, the VHI paradigm typically targets hairy skin without comparisons to glabrous skin. The aim of this article was to investigate illusory body ownership, the applicability of ultrasonic mid-air haptics, and perceived immersion in VR using the VHI. Fifty participants viewed a virtual hand being stroked by a feather synchronously and asynchronously with the ultrasonic stimulation applied to the glabrous skin on the palmar surface and the hairy skin on the dorsal surface of their hands. Questionnaire responses revealed that synchronous stimulation induced a stronger VHI than asynchronous stimulation. In synchronous conditions, the VHI was stronger for palmar stimulation than dorsal stimulation. The ultrasonic stimulation was also perceived as more intense on the palmar surface compared to the dorsal surface. Perceived immersion was not related to illusory body ownership per se but was enhanced by the provision of synchronous stimulation

The effect of task on visual attention in interactive virtual environments

Virtual environments for gaming and simulation provide dynamic and adaptive experiences, but, despite advances in multisensory interfaces, these are still primarily visual experiences. To support real-time dynamic adaptation, interactive virtual environments could implement techniques to predict and manipulate human visual attention. One promising way of developing such techniques is to base them on psychophysical observations, an approach that requires a sound understanding of visual attention allocation. Understanding how this allocation of visual attention changes depending on a user’s task offers clear benefits in developing these techniques and improving virtual environment design. With this aim, we investigated the effect of task on visual attention in interactive virtual environments. We recorded fixation data from participants completing freeview, search, and navigation tasks in three different virtual environments. We quantified visual attention differences between conditions by identifying the predictiveness of a low-level saliency model and its corresponding color, intensity, and orientation feature-conspicuity maps, as well as measuring fixation center bias, depth, duration, and saccade amplitude. Our results show that task does affect visual attention in virtual environments. Navigation relies more than search or freeview on intensity conspicuity to allocate visual attention. Navigation also produces fixations that are more central, longer, and deeper into the scenes. Further, our results suggest that it is difficult to distinguish between freeview and search tasks. These results provide important guidance for designing virtual environments for human interaction, as well as identifying future avenues of research for developing “attention-aware” virtual worlds