The perception of manoeuvres of moving vehicles. Progress Report V: Thresholds for relative vehicle motion in depth : a check in the field.

The conclusion previously drawn from laboratory experimentation that a change in angular separation between a vehicle's taillights, rather than a change in their apparent size or brightness, is the cue in detection of relative vehicle motion in depth was tested in a field situation. The results were essentially in agreements with the predictions made on the basis of this conclusion.