Perception distance is the distance show how your vehicle travels?

It takes time for your brain to process information. Perception time is the period of time between the moment your eyes pick up on a hazard and the moment your brain decides it's a hazard that needs your action. Your perception time may last up to one-third of a second. The distance your car perceives is the distance it will cover in that period of time. Before you even realize you need to react to the hazard, your car will have traveled 61 feet at a speed of 55 mph in 3/4 of a second.