Abstract
In the present paper, the effect of very short viewing times of less than 1 s on time-to-collision (TTC) perception was investigated, because the latency of saccadic eye movement is about 200 ms. In our experiments, an approaching vehicle was simulated as a square. In Experiment 1, the perceived speed for an approaching object was investigated using the magnitude estimation method, without considering depth perception. In Experiment 2, discrete views of the approaching vehicle were simulated, thus removing optic flow information, and Experiment 3 investigated the shortest possible viewing time to be able to estimate the TTC. Under more realistic conditions, Experiment 4 simulated the shortest viewing time with two discrete views of the object. The results are as follows: (1) If the viewing time of the approaching object was short, its speed was underestimated. (2) It was impossible to estimate the TTC of an approaching object without optic flow. (3) It was possible to estimate the TTC when the optic flow existed, even for viewing times of just 0.3 s. (4) Drivers might estimate the TTC using optic flow information from their last view of the object, rather than intermittently obtained information.
Keywords: Very-short viewing time, time-to-collision (TTC), velocity, perception, optic flow