Auditory Self-Motion Simulation is Facilitated by Haptic and Vibrational Cues Suggesting the Possibility of Actual Motion

Sound fields rotating around stationary blindfolded listeners sometimes elicit auditory circular vection, the illusion that the listener is physically rotating. Experiment 1 investigated whether auditory circular vection depends on participants\u27 situational awareness of "movability", i.e., whether they sense/know that actual motion is possible or not. While previous studies often seated participants on movable chairs to suspend the disbelief of self-motion, it has never been investigated whether this does, in fact, facilitate auditory vection. To this end, 23 blindfolded participants were seated on a hammock chair with their feet either on solid ground ("movement impossible") or suspended ("movement possible") while listening to individualized binaural recordings of two sound sources rotating synchronously at 60 degrees. Although participants never physically moved, situational awareness of movability facilitated auditory vection. Moreover, adding slight vibrations like the ones resulting from actual chair rotation increased the frequency and intensity of vection. Experiment 2 extended these findings and showed that nonindividualized binaural recordings were as effective in inducing auditory circular vection as individualized recordings. These results have important implications both for our theoretical understanding of self-motion perception and for the applied field of self-motion simulations, where vibrations, non-individualized binaural sound, and the cognitive/perceptual framework of movability can typically be provided at minimal cost and effort

Self-motion illusions ("vection") in Virtual Environments: Do active control and user-generated motion cueing enhance visually induced vection?

The human perceptual system can be tricked into believing that one is moving, when in fact, one is not. These self-motion illusions (vection) can be exploited to convincingly simulate self-motion without the need for costly and cumbersome motion platforms. Traditionally, vection has been elicited by moving visual stimuli on custom optokinetic drums or virtual reality (VR) setups. Surprisingly, little is known about contributions of cross-modal effects on vection in contemporary, interactive VR applications. Two studies investigated the effect of active versus passive locomotion and small, actively versus passively generated physical motion cues on optic flow based vection. Twenty four participants used a joystick or gaming chair to navigate on curved (experiment 1, training) or a combination of curved and straight trajectories (experiment 2, main study) presented in an immersive, 3D VR system. The gaming chair allowed for 10 centimeter forward/backward and left/right swivel motions of the seat. Participants experienced four conditions: 1) just watching the scene (passive, no motion cueing), 2) motion cues applied to the participant’s seat (passive, motion cueing), 3) joystick locomotion (active, no motion cueing) and 4) participants using the gaming chair for locomotion (active, motion cueing). Overall, participants took 16% longer to experience vection for active compared to passive locomotion. Small, physical motion cues increased vection intensity by 22%. Trajectory curvature most consistently affected vection. Participants experienced vection 34% more intense, 20% earlier and 9% more likely during narrow turns compared to straight paths. Participants experienced vection up to 18% earlier in experiment 2 over experiment 1 possibly due to training effects. It seems that actively controlling locomotion may have distracted participants from the motion stimulus or the task of reporting vection. It became evident that smoothness, precision and ease-of-use of the interface were possible factors that affected vection. In conclusion, vection can be enhanced by using simple motion paradigms and adding curved trajectories to the simulation at minimal cost and effort. For interactive applications, prudent selection of interaction paradigms and ample training is advised