reaction time

Many experiments have been done to see how quickly a person can respond to a stimulus. For example, how much time passes between the moment a driver sees the brake lights of the car ahead come on, and the moment he slams on the brakes? Some of the results are curious: if you are right-handed, you can respond with your right hand about 3% faster than with your left – and conversely for a left-handed person. Responding with the feet takes about 20% longer than responding with the hands.

The most important experimental result is one everyone knows: past the age of 40 reaction time increases. Notice, however, that 30-year-olds react faster than 20-year-olds. The table below compares reaction times to a stimulus that is seen (a light coming on) and one that is heard (a buzzer).

Reaction Time (milliseconds)
females males
stimulus seen stimulus heard stimulus seen stimulus heard
20 320 310 240 230
30 260 200 220 190
40 340 300 260 240
50 360 300 270 250
60 440 420 380 370

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