Pretto Paolo, Bresciani Jean-Pierre, Rainer Gregor, Bülthoff Heinrich H
Department of Human Perception, Cognition and Action , Max Planck Institute for Biological Cybernetics , Tübingen , Germany.
Elife. 2012 Oct 30;1:e00031. doi: 10.7554/eLife.00031.
Visual speed is believed to be underestimated at low contrast, which has been proposed as an explanation of excessive driving speed in fog. Combining psychophysics measurements and driving simulation, we confirm that speed is underestimated when contrast is reduced uniformly for all objects of the visual scene independently of their distance from the viewer. However, we show that when contrast is reduced more for distant objects, as is the case in real fog, visual speed is actually overestimated, prompting drivers to decelerate. Using an artificial anti-fog-that is, fog characterized by better visibility for distant than for close objects, we demonstrate for the first time that perceived speed depends on the spatial distribution of contrast over the visual scene rather than the global level of contrast per se. Our results cast new light on how reduced visibility conditions affect perceived speed, providing important insight into the human visual system.DOI:http://dx.doi.org/10.7554/eLife.00031.001.
人们认为在低对比度情况下视觉速度被低估了，这被认为是雾天驾驶速度过快的一种解释。结合心理物理学测量和驾驶模拟，我们证实，当视觉场景中所有物体的对比度都均匀降低时，无论它们与观察者的距离如何，速度都会被低估。然而，我们发现，当远处物体的对比度降低得更多时，就像在真实雾天中那样，视觉速度实际上被高估了，这会促使驾驶员减速。使用一种人工造雾——即远处比近处能见度更好的雾，我们首次证明，感知到的速度取决于视觉场景中对比度的空间分布，而不是对比度本身的全局水平。我们的研究结果为能见度降低的条件如何影响感知速度提供了新的线索，为人类视觉系统提供了重要的见解。DOI:http://dx.doi.org/10.7554/eLife.00031.001
