What is reaction distance?

Question

Your vehicle's stopping distance can be calculated by adding together your perception distance, your reaction distance, and your vehicle's braking distance. Reaction distance is the distance traveled between the moment you mentally perceive a hazard and the moment you physically hit the brakes.

Accepted Answer

The distance you will travel between realizing you must brake and when you physically hit the brakes

Answer

The distance you will travel between a hazard becoming visible and you seeing the hazard

Answer

The distance you will travel between seeing a hazard and realizing you must brake