Saw it or triggered it: Exploring the threshold of implicit and explicit interaction for eye-tracking technique in virtual reality

With eye-tracking techniques, the virtual reality (VR) system can acquire what the user is looking at in the virtual environment (VE). Most previous works focused on eye-tracking interaction in VR with explicit interactions. In this paper, we tried to determine whether the eye-tracking techniques can be applied as implicit interactions. With implicit eye-tracking interactions, users could trigger the story events unconsciously without missing them. The approaches could be interactive techniques for enhancing VR storytelling. We conducted a user study to investigate the threshold of implicit and explicit interaction for the eye-tracking technique in VR. We designed three interfaces: objects lighting, objects movement, and objects sound, for users to judge whether they trigger objects in the VE or not when seeing them. The result provides a parameter in the design guideline for immersive storytelling with the eye-tracking device and brings a new VR storytelling technique.