"Kapow!": Studying the Design of Visual Feedback for Representing Contacts in Extended Reality.

In absence of haptic feedback, the perception of contact with virtual objects can rapidly become a problem in extended reality (XR) applications. XR developers often rely on visual feedback to inform the user and display contact information. However, as for today, there is no clear path on how to design and assess such visual techniques. In this paper, we propose a design space for the creation of visual feedback techniques meant to represent contact with virtual surfaces in XR. Based on this design space, we conceived a set of various visual techniques, including novel approaches based on onomatopoeia and inspired by cartoons, or visual effects based on physical phenomena. Then, we conducted an online preliminary user study with 60 participants, consisting in assessing 6 visual feedback techniques in terms of user experience. We could notably assess, for the first time, the potential influence of the interaction context by comparing the participants' answers in two different scenarios: industrial versus entertainment conditions. Taken together, our design space and initial results could inspire XR developers for a wide range of applications in which the augmentation of contact seems prominent, such as for vocational training, industrial assembly/maintenance, surgical simulation, videogames, etc.