Moroz Matthew, Garzorz Isabelle, Folmer Eelke, MacNeilage Paul
Department of Psychology, University of Nevada, Reno.
Graduate School of Systemic Neurosciences, Ludwig-Maximilians-Universität München.
Displays. 2019 Jul;58:12-19. doi: 10.1016/j.displa.2018.09.001. Epub 2018 Sep 5.
A primary cause of simulator sickness in head-mounted displays (HMDs) is conflict between the visual scene displayed to the user and the visual scene expected by the brain when the user's head is in motion. It is useful to measure perceptual sensitivity to visual speed modulation in HMDs because conditions that minimize this sensitivity may prove less likely to elicit simulator sickness. In prior research, we measured sensitivity to visual gain modulation during slow, passive, full-body yaw rotations and observed that sensitivity was reduced when subjects fixated a head-fixed target compared with when they fixated a scene-fixed target. In the current study, we investigated whether this pattern of results persists when (1) movements are faster, active head turns, and (2) visual stimuli are presented on an HMD rather than on a monitor. Subjects wore an Oculus Rift CV1 HMD and viewed a 3D scene of white points on a black background. On each trial, subjects moved their head from a central position to face a 15° eccentric target. During the head movement they fixated a point that was either head-fixed or scene-fixed, depending on condition. They then reported if the visual scene motion was too fast or too slow. Visual speed on subsequent trials was modulated according to a staircase procedure to find the speed increment that was just noticeable. Sensitivity to speed modulation during active head movement was reduced during head-fixed fixation, similar to what we observed during passive whole-body rotation. We conclude that fixation of a head-fixed target is an effective way to reduce sensitivity to visual speed modulation in HMDs, and may also be an effective strategy to reduce susceptibility to simulator sickness.
头戴式显示器（HMD）中模拟器晕动症的一个主要原因是，当用户头部运动时，呈现给用户的视觉场景与大脑预期的视觉场景之间存在冲突。测量HMD中对视觉速度调制的感知敏感度很有用，因为将这种敏感度降至最低的条件可能不太容易引发模拟器晕动症。在先前的研究中，我们测量了在缓慢、被动的全身偏航旋转过程中对视觉增益调制的敏感度，观察到与注视场景固定目标相比，当受试者注视头部固定目标时，敏感度会降低。在当前的研究中，我们调查了以下两种情况下，这一结果模式是否依然存在：（1）运动速度更快，为主动转头；（2）视觉刺激呈现在HMD上，而非显示器上。受试者佩戴Oculus Rift CV1 HMD，观看黑色背景上白点的3D场景。在每次试验中，受试者将头部从中心位置移动到面对一个偏离中心15°的目标。在头部移动过程中，他们根据条件注视一个头部固定或场景固定的点。然后他们报告视觉场景运动是太快还是太慢。随后试验中的视觉速度根据阶梯程序进行调制，以找到刚好能察觉的速度增量。在主动头部运动过程中，与我们在被动全身旋转过程中观察到的情况类似，在注视头部固定目标时，对速度调制的敏感度降低。我们得出结论，注视头部固定目标是降低HMD中对视觉速度调制敏感度的有效方法，也可能是降低模拟器晕动症易感性的有效策略。
