Estimating time-to-contact when vision is impaired

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.

Auditory Information Improves Time-to-collision Estimation for Accelerating Vehicles

“…Hence, participants could still have made first-order TTC estimates in the AV condition but then shortened their estimates by an absolute amount of time (e.g., 1 s) as a consequence of the detected (potentially dangerous) acceleration. This would be compatible with a safety strategy previously observed with, e.g., blurred vision (Hecht et al, 2021), and threatening sounds (Braly et al, 2021). When using such a strategy, the mean TTC estimates in the AV condition in Fig.…”

The effect of contrast on pedestrians’ perception of vehicle speed in different road environments

“…Although observers are able to judge the time-to-arrival of an approaching object by optical variables, such as the ratio between its retinal image size and rate of expansion (e.g., Lee, 1976;Lee, Young, Reddish, Lough, & Clayton, 1983), perceptual biases affecting its perceived speed and distance are often found to also affect time-to-arrival estimates. For example, a reduction in contrast lengthens the perceived time-to-arrival both when an object is viewed moving across the frontoparallel plane (Battaglini, Campana & Casco, 2013) and when viewed frontally as if approaching the observer (Hecht, Brendel, Wessels & Bernhard, 2021). The increase of the perceived time-to-arrival supposedly results from a reduction in the perceived speed or, alternatively in the latter case, an increase of the perceived distance.…”

A binary acceleration signal reduces overestimation in pedestrians’ visual time-to-collision estimation for accelerating vehicles

“…Previous studies analyzed either the standard deviation ( SD ) or the coefficient of variation (i.e., SD divided by mean) (e.g., Refs. [ [42] , [43] , [44] , [45] ]). However, both metrics have certain limitations in interpretation.…”

“…Thus, the acceleration signal might have enabled an “elaborate” change in estimation strategy, rather than promoting a simple safety strategy in form of an unspecific shortening of the estimated TTCs whenever the acceleration signal was present (e.g., by a constant duration or proportionally) (e.g., Ref. [ 44 ]).…”