“Hips don’t lie”: mitigating the perception of rotation gains using the hanger reflex in virtual reality

Abstract

In virtual reality (VR), rotation gains scale the mapping between a user’s physical and virtual rotation, helping users explore larger virtual environments within limited tracked spaces. Prior work has shown that visual scene properties, attentional demands, and turning dynamics influence whether such gains are detected, but less is known about how haptic feedback modulates rotation-gain perception. We investigate this question using the Hanger Reflex (HR), a tactile illusion in which localized pressure on soft tissue elicits an involuntary rotational tendency. Although HR has previously been applied to the head and waist for motion feedback and guidance, its effect on rotation-gain perception during VR turning remains unclear. In this paper, we present a wearable pneumatic belt for targeted hip HR stimulation and evaluate whether hip-based HR changes perceived rotation gains in VR. Twelve participants performed stationary 90° turns and judged whether the virtual rotation felt smaller or greater than their physical rotation. We compared three haptic conditions: no stimulation, hip HR stimulation aligned with the turn direction (ipsilateral), and hip HR stimulation opposing the turn direction (contralateral). Contralateral hip HR shifted the fitted psychometric functions toward higher gain values relative to ipsilateral stimulation and the no-stimulation baseline, especially for the point of subjective equality and the 25% threshold. Contralateral stimulation also increased head-hip delays, indicating that hip HR modulates body-segment coordination during turning. These findings identify hip HR as a promising haptic component for VR redirection, where non-visual feedback may help shape multisensory evidence during rotational movement.