Jason's+Research

** 1. Mental Processing Time **

 * ====Sensation: The time it takes to detect the sensory input from an object. Auditory is usually better than your response according to your eyes. The louder, brighter, bigger the object, the faster you would respond.====
 * ====Situational awareness: The time needed to recognize and interpret the scene. If there's an accident ahead, the time you have to be aware of the "situation".====
 * ====Perception/recognition: The time needed to recognize the meaning of the sensation. For example it's like you see it but it's the time taken to recognize what it is. It could technically be anything (person, plane(not likely), train, accident, ect.)====
 * ====Response selection: The time needed to actually put your brain in action and making your body part move like braking. Experienced drivers do this without recognizing it way before you do it.====

The time needed to actually come to a stop, you may have touched the brake but you will gradually slow down still covering more distance. Adding in the response time, and the physical force.
====Reaction times also depend on many other things. For example, expectations. When you push on the brake, you expect it to slowly slow down but if it doesn't go down as easy as you expected, that would add another half a second. Another thing is urgency If you are right before a collision, you would respond much quicker than your normal time. The setting is also a factor. If the driver is focusing on winding roads, the driver's reaction time would be lower. One obvious thing is age, younger people tend to have a slower response(muscle memory). Another theory says gender also affects it. Although it's not proven, females tend to have a slower reaction time than males. Another obvious one is visibility. If you can't see much until very close, the reaction time would be longer because they would've not expected it. Drinking decreases your mental ability to think in general. Having many passengers could make you worried or they could be very loud and distracting.====

I got most of this information from http://www.visualexpert.com/Resources/reactiontime.html