After a person becomes aware of a dangerous situation, some time will elapse before he can take evasive or defensive action against it. This time interval, commonly called the reaction time, has been found to be roughly 0.7 seconds for all normal persons, regardless of their background and training. This suggests that the reaction time depends on some basic aspect of the human physiology-involving the brain, nervous system, and muscles-which does not vary much from person to person. It also takes a finite amount of time for a person to perceive that there is a dangerous situation that requires action; the combined time for a person to perceive a threat and react to is is known as the perception-reaction time. This combined time is, of course, slightly longer than the reaction time; in cases relevant to accident reconstruction it is often on the order of 1.5 seconds, though it can be slightly faster (near 0.7 seconds) if the situation is anticipated to some degree. Alternatively, a highly ambiguous situation, where the need for a reaction is not obvious, can result in an even higher perception-reaction time.
Posted on: Sun, 23 Nov 2014 02:34:17 +0000
Recently Viewed Topics
© 2015