Accuracy of estimating time to collision using binocular and monocular information

Abstract

We measured both the just-noticeable difference in time to collision (TTC) with an approaching object, and the absolute accuracy in estimating TTC in the following cases: only binocular information available; only monocular information available; both binocular and monocular information available as in the everyday situation. Observers could discriminate trial-to-trial variations in TTC on the basis of binocular information alone: the just-noticeable difference in TTC (5.1-9.8%) was the same for a small (0.03 deg) target and for a large (0.7 deg) target. In line with previous reports, when only monocular information was available, the just-noticeable difference in TTC was 5.8-12% for the large target. However, observers could not reliably discriminate trial-to-trial variations in TTC with the small target when only monocular information was available. When both binocular and monocular information was available, the just-noticeable difference in TTC for the large target was not significantly different from when only binocular or only monocular information was available. Observers could make reliable estimates of absolute TTC using binocular information only. Errors ranged from 2.5 to 10% for the large target, and 2.6 to 3.0% for the small target, all being overestimates. Errors for the small target were the same or lower than errors for the large target. Observers could make reliable estimates of TTC with the large target using monocular information only. Errors ranged from 2.0 to 12%, all being underestimates. Since monocular information did not provide a basis for reliable estimates of absolute TTC with the small target we conclude that, in everyday conditions, accurate estimates of TTC with small targets are based on binocular information when the object is small and is no more than a few metres away. Errors in estimating absolute TTC were lower in the case where both binocular and monocular information were available (as in the everyday situation) than when only binocular information or only monocular information was available. Errors ranged from 1.3 to 2.7%. An error of 1.3% approaches the accuracy required to explain the +/- 2.0-2.5 msec accuracy with which top sports players can estimate the instant of impact between bat and ball.

Estimating the relative weights of visual and auditory tau versus heuristic-based cues for time-to-contact judgments in realistic, familiar scenes by older and younger adults

“…Thus, as expected, both the accurate cue (TTC v ) and heuristic cues such as the final optical size were significantly associated with the TTC estimates. This finding is compatible with data from DeLucia et al (2016), obtained in both an audio-visual and a visual-only condition, whereas Gray and Regan (1998) reported that the final optical size, final rate of optical expansion and the change in visual angle across the presentation duration showed no relation to TTC estimates in a visual-only condition. As expected, the TTC estimates increased with the actual visual TTC, with the final visual distance (Law et al, 1993), and with the inverse of the final optical size (DeLucia, 1991).…”

“…Vehicle size and presentation duration were varied in order to reduce the correlations between such cues as final optical size and final rate of expansion (cf. Gray & Regan, 1998;Oberfeld, Hecht, & Landwehr, 2011), so that the observer's weightings of these cues could be more easily estimated in the analyses. Consequently, the starting distance of the vehicle varied across trials on the basis of presentation duration, vehicle speed, and TTC level (see the Study Design section for details).…”

“…These include the final rate of optical expansion ( ⋅ θ final ; Gray and Regan, 1998), the change in visual angle across the presentation duration (Δθ = θ final − θ initial ; Gray & Regan, 1998), and the final visual distance of the stimulus (D final v ; Yan, Lorv, Li, & Sun, 2011). In the present study, we measured the influence of each of these three visual heuristic cues on TTC judgments.…”

“…Some of these cues have been studied using visual stimuli (Gray & Regan, 1998;Yan et al, 2011), but not using auditory stimuli, or combined visual and auditory stimuli. Further, prior studies have used relatively simple stimuli and thus, it is not known whether the relative weighting of visual and auditory cues in TTC judgments, and the relative use of τ-based information and heuristics cues, would be different under more naturalistic conditions.…”

The contribution of stereo vision to one-handed catching

“…These findings indicate that multiple sources of monocular and binocular information may contribute to the timing of a catch. Similar results were obtained by Gray and Regan (1998), who showed in several psychophysical experiments that more accurate ttc judgements were made when both monocular and binocular information was available. Second, Rushton and Wann (1999) applied virtual reality to create a similar misjudgement: participants had to catch virtual balls of which the diameter was computationally scaled, so that the ball appeared to arrive 100 ms earlier or later than specified by retinal disparity.…”