Abstract
Often, we have to rely on limited information when judging time-to-contact (TTC), as for example, when driving in foul weather, or in situations where we would need reading glasses but do not have them handy. However, most existing studies on the ability to judge TTC have worked with optimal visual stimuli. In a prediction motion task, we explored to what extent TTC estimation is affected by visual stimulus degradation. A simple computer-simulated object approached the observer at constant speed either with clear or impaired vision. It was occluded after 1 or 1.5 s. The observers extrapolated the object’s motion and pressed a button when they thought the object would have collided with them. We found that dioptric blur and simulated snowfall shortened TTC-estimates. Contrast reduction produced by a virtual semi-transparent mask lengthened TTC estimates, which could be the result of distance overestimation or speed underestimation induced by the lower contrast or the increased luminance of the mask. We additionally explored the potential influence of arousal and valence, although they played a minor role for basic TTC estimation. Our findings suggest that vision impairments have adverse effects on TTC estimation, depending on the specific type of degradation and the changes of the visual environmental cues which they cause.
Highlights
Often, we have to rely on limited information when judging time-to-contact (TTC), as for example, when driving in foul weather, or in situations where we would need reading glasses but do not have them handy
Poor visibility affects visuo-motor performance, but to what extent are TTC estimates affected? For instance, precipitation is associated with large increases in traffic collisions and injuries[8], and driving with impaired vision is associated with an increased risk of at-fault c rashes[9]
We investigated what effects visual impairments might have on frontal TTC estimation using a prediction motion paradigm
Summary
We have to rely on limited information when judging time-to-contact (TTC), as for example, when driving in foul weather, or in situations where we would need reading glasses but do not have them handy. Besides the obvious effects of precipitation and impaired vision—like a slippery ground or not detecting an obstacle in time—more subtle effects of such conditions on visual perception may be at work Among the latter, we chose to examine the role of complex visual impairment on TTC estimation, as brought about by fog, poor eye-sight, or snowfall. Among the most common symptoms of cataracts are cloudy or blurry vision and the phenomenon that colors seem faded[10] Such reductions of contrast and/or contrast sensitivity are associated with self-reported driving difficulty[11,12], increased at-fault crash risk[9,13] as well as performance changes. As outlined, impaired vision is relevant in driving contexts, and many studies investigating the role of reduced contrast adopted this context. Aside from the effect of contrast, other experiments have observed changes in luminance to affect speed perception, in terms of speed underestimation with increased luminance[15,16,17]
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