Reaction time is the time from when a driver notices something to when they decide what to do.

Through experience and concentration, a driver may affect his reaction time because an experienced, concentrated driver is normally better able to 'read' the traffic situation and decide quickly the most suitable reaction.

An experienced, concentrated driver is also normally better at anticipating and identifying potential hazards, which also shortens the so-called inattention time ('uoppmerksomhetstiden').