Body warping Versus Change blindness remapping
A Comparison of Two Approaches to Repurposing Haptic Proxies for Virtual Reality
In the 7th-semester master's project at AAU-CPH, we decided to change things up and explore hand redirection in VR. It attracted us because hand redirection research aims to solve another big problem in VR: touch. We are used to touching objects with our hands. When you reach for your cup, you feel it in your hand, the shape, and the weight. This results in a holistic sensory experience, but haptic feedback is also essential for movement control, accuracy, and learning. ​
Hand redirection can provide touch feedback by repurposing physical proxies for multiple virtual objects. We tried to challenge the hand redirection monopolly by comparing it to change blindness remapping, which manipulates the environment instead of user movements.
For the study, we designed a setup that includes four physical buttons. Each button is mapped to six virtual buttons, evenly spaced to allow mapping objects at multiple distance levels. Measuring the tolerated distance between the real and virtual button lets us compare how practical and efficient each technique was.
Similar to our previous research projects, the experimental task was gamified. We wanted to make it more interesting for us to develop and for participants to experience. Also, expertise from our previous research projects suggests that making the experiment more like an actual application will yield a more realistic result. Therefore, we built the virtual environment to resemble a space workstation.
The participants had to save the space workstation by following instructions. The orange screen displayed which button the participants had to press as fast as possible. The screen was positioned so the participants would look away. During this time, the virtual buttons were shifted for the change blindness remapping to work.
By far the most challenging aspect of working with physical proxies is correctly aligning the virtual and real objects. Any misalignment can bias participants' perception of being manipulated. We design the virtual button stokes to match how the physical button moved. Additionally we made sure to match the size and shape of the buttons as closely as possible. We minimized the headset tracking errors by providing consistent indoor lighting.
Change blindness remapping objectively performed better than haptic retargeting. Detection thresholds for change blindness were better by 1.8 cm. Furthermore, haptic retargeting was rated worse on embodiment, mainly because hand movements felt less in control. This concludes that change blindness remapping can be nicer than haptic retargeting for VR applications. But the drawback is that the manipulation must be hidden, for example, by forcing participants to look away. While haptic retargeting does not need such strategies for implementation.