What fraction of a second is typically the reaction time between seeing a problem and applying the brakes?

The typical reaction time between seeing a problem on the road and applying the brakes is generally around three-quarters of a second. This timeframe accounts for the moment it takes for the driver to visually perceive a hazard, process that information, and then initiate the physical response to apply the brakes.

Human reaction time can vary due to several factors, including the driver’s alertness, the complexity of the situation, and external conditions such as visibility and distractions. While this reaction time can indeed fluctuate, ¾ of a second is a commonly accepted average for standard situations, making it the most accurate choice among the given options.

In contrast, a reaction time of ½ second may be applicable in very urgent situations or for exceptionally alert drivers, while 1 second or longer would represent a slower response than what is typically expected in vital driving contexts. A reaction time of 1 ½ seconds is considerably lengthy for immediate driving reactions, making it less relevant for everyday scenarios where quick responses are crucial for safety.