Vollette Carole-Anne, Bockisch Christopher J, Bertolini Giovanni
University of Zürich, Zürich, Switzerland.
Departments of Ophthalmology, Neurology and Otorhinolaryngology, Head and Neck Surgery, University Hospital Zürich, University of Zürich, Zürich, Switzerland.
Front Neurol. 2025 Aug 7;16:1623749. doi: 10.3389/fneur.2025.1623749. eCollection 2025.
Passive motions can lead to conflicting combinations of visual and vestibular signals that can have a tremendous impact on our ability to navigate and comprehend the world. However, conflicting motion signals are also exploited for rehabilitation, adaptation training, and entertainment by creating functional illusions (VR, amusement parks). Low-frequency linear translations can induce "hilltop illusions," a perceptual phenomenon consisting in a reinterpretation of the inertial acceleration as tilt with respect to gravity. Compared to other vestibular stimuli, the hilltop illusion has rarely been used as it is considered unpractical due to the complexity of the necessary motion devices, which can have high operational costs, induce cognitive biases jeopardizing the illusion and discomfort in the subject. We hypothesize that a practical protocol to create and quantify a hilltop illusion can be realized using low-frequency (0.16 Hz) small-amplitude (0.45 m) translations on a standard motion simulator (Stewart Platform), provided that expectations and awareness of the illusion are hindered. To this aim, we combined the lateral oscillations with 90° phase-shifted roll movement with a random direction and amplitude. A consistent tilt illusion was measured across 12 healthy participants (29.7 ± 14.5 yo, 6 females). The hilltop illusion was quantified using both haptic vertical (HV) and subjective visual vertical (SVV) assessments, showing a significant tilt perception with larger values displayed in HV (2.2° ± 1.2-gain to the GIA tilt = 41.8%) compared to SVV (0.51° ± 0.57-gain = 9.7%). The protocol was well tolerated, with minimal motion sickness reported. This new protocol offers an accessible method for the generation of an implicit vestibular illusion, while demonstrating the importance of preventing cognitive awareness of motion cues. It offers insights in the perceptual process of vestibular conflicts and provides a foundation for potential development of diagnostic and therapeutic applications, for training and for illusions.
被动运动可能会导致视觉和前庭信号的冲突组合，这可能会对我们导航和理解世界的能力产生巨大影响。然而，通过创造功能性错觉（虚拟现实、游乐园），冲突的运动信号也被用于康复、适应性训练和娱乐。低频线性平移可以诱发“山顶错觉”，这是一种感知现象，即把惯性加速度重新解释为相对于重力的倾斜。与其他前庭刺激相比，山顶错觉很少被使用，因为由于所需运动设备的复杂性，它被认为不实用，这种设备可能运营成本高昂，会引发认知偏差，危及错觉效果，并使受试者感到不适。我们假设，使用标准运动模拟器（斯图尔特平台）进行低频（0.16赫兹）小幅度（0.45米）平移，可以实现一种实用的方案来创造和量化山顶错觉，前提是阻碍受试者对错觉的预期和意识。为此，我们将横向振荡与90°相移的滚动运动相结合，滚动运动方向和幅度随机。对12名健康参与者（29.7±14.5岁，6名女性）进行测量，发现存在一致的倾斜错觉。使用触觉垂直（HV）和主观视觉垂直（SVV）评估对山顶错觉进行量化，结果显示与SVV（增益0.51°±0.57 = 9.7%）相比，HV显示出显著的倾斜感知，增益更大（2.2°±1.2 - 相对于重力惯性加速度倾斜（GIA）倾斜的增益 = 41.8%）。该方案耐受性良好，报告的晕动病症状极少。这种新方案提供了一种生成隐性前庭错觉的可行方法，同时证明了防止对运动线索产生认知意识的重要性。它为前庭冲突的感知过程提供了见解，并为诊断和治疗应用、训练以及错觉的潜在发展奠定了基础。
