Interpreting FMS and SSQ Cybersickness Ratings via User Tolerance in Virtual Reality

Cybersickness remains a persistent challenge limiting the usability of virtual reality (VR), yet commonly used subjective measures such as the Simulator Sickness Questionnaire (SSQ) and the Fast Motion Sickness (FMS) scale are often difficult to interpret in terms of user outcomes. In particular, there is limited guidance on how specific values on these scales relate to user tolerance or the likelihood that users will discontinue a VR experience due to discomfort. This work addresses this gap by calibrating cybersickness severity interpretations against early termination of a VR experience. In Study 1 (N = 183), participants played an immersive VR game for up to 20 minutes and were free to terminate the experience at any time. Using a Behavioral Risk Banding (BRB) framework, logistic regression linked a modified 0-10 version of the FMS (FMS-10) and post-exposure SSQ scores to dropout probability, yielding behaviorally grounded risk severity bands (mild, moderate, severe, extreme). Survival analyses then showed how these bands mapped onto tolerance over time, revealing a transitional region marked by heightened individual variability. Study 2 (N = 304) evaluated the robustness of these empirically derived severity categories across variation in VR content and mitigation context by applying the Study 1 thresholds without re-estimation. Although absolute dropout risk varied, the ordering and behavioral meaning of severity categories were preserved. Together, these results provide a practical, behaviorally grounded framework and empirically derived thresholds for interpreting SSQ and FMS cybersickness scores in terms of user tolerance and VR usability across contexts.