Cybersickness follows sensory conflict theory (Reason & Brand, 1975): the brain expects vision and the vestibular system (inner-ear semicircular canals + otoliths) to report self-motion in agreement. In a seated VR headset your eyes report large, fast optic flow — vection — while your vestibular system correctly reports that you never actually moved. That unresolved mismatch is what the nervous system reads as a poisoning cue, triggering nausea.
C(t) = w_fov·fov_n + w_speed·v_n + w_turn·ω_n·(1 − 0.6·snap) + w_lat·L_n
S(t) = clamp( S(t−dt) + k·C(t)·dt − d·dt , 0, 100 )
where fov_n, v_n, ω_n, L_n are the field-of-view, locomotion speed, turn rate and latency each normalised to their slider range, C(t) is the instantaneous conflict index (0–100), and S(t) is the slowly-integrating, slowly-decaying exposure score used for the risk category — mirroring how real Simulator Sickness Questionnaire scores build up over a session rather than reacting instantly. This is the same model as the 3D version of this simulator, reproduced here with an independent 2D pseudo-perspective renderer (perspective-projected concentric rings, no WebGL) instead of a real 3D engine.
- Field of view & speed — a wider FOV and faster optic flow recruit more peripheral retina, which drives vection strength and conflict fastest (the single biggest predictor in cybersickness research).
- Turn rate / locomotion mode — continuous smooth turning keeps visual rotation running with no matching vestibular signal; snap-turning (discrete jumps) trades a brief disorientation spike for long stretches with near-zero rotational conflict, which is why most shipped VR titles default to it.
- Latency — the delay between a motion command and the rendered response (tracked here by literally rendering the tunnel from a buffered, time-delayed camera state) adds a prediction-error term found in every major cybersickness study; above ~50 ms it becomes noticeable, above ~150 ms it dominates.
- The inset (top-right of the tunnel) shows the two conflicting signals directly: the blue arrow is the visual heading your eyes see (the delayed, controller-driven yaw that feeds the conflict formula); the red dot stays pinned near true-down because the vestibular system correctly senses the headset wearer never rotated their body.
- Drag to look around — click/touch-drag the tunnel to pan your view left/right, exactly like turning your head while seated. This does not add to the conflict index: a real head turn is genuinely sensed by the vestibular system too, so vision and balance agree — it is the pure, controller-driven "smooth turn" that has no matching vestibular signal.
- The strip chart below the tunnel plots the conflict index and exposure score over the last 20 seconds, so you can see the score integrate and decay in real time as you change sliders.