Discrimination and Estimation of Time-to-Contact for Approaching Traffic Using a Desktop Environment

A. Elizabeth Seward, Daniel H. Ashmead, and Bobby Bodenheimer


Each year, thousands of pedestrians are injured or killed in traffic accidents. Identifying pedestrians' perceptual capabilities for street crossing decisions is an important problem. This paper examines this issue by seeking to understand people's time-to-contact judgments for short-range to long-range times-to-contact in a desktop environment. Two experiments were used to test time-to-contact judgments around 4, 7, and 10 seconds. Both experiments showed subjects videos of a car moving down a road toward the viewer. The first experiment observed subjects' ability to discriminate between two different time-to-contact values. The second experiment measured subjects' absolute time-to-contact estimates. We found subjects to be accurate at both discriminating and estimating time-to-contact in a desktop environment. However, performance worsens at longer time ranges, those that pedestrians typically use in street-crossing decisions. Our discrimination thresholds are consistent with other time-to-contact work, and thus illustrate that desktop environments are plausible settings to use for time-to-contact studies.

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Bobby Bodenheimer