Detection of the sign of relative motion when following a vehicle.

The ability to detect the sign of relative motion in the driving situation was investigated on a freeway. Subject passengers in a specially instrumented vehicle were given controlled looks of a lead car. It was the subject's task to estimate whether the two cars had come closer or moved further apart during the exposure. The comparative ability of nine stimulus functions to predict the detection of the sign of relative motion was examined. The results of the experiment indicate considerable sensitivity to the sign of relative motion. (See also B 3917).