Reaction time

Signal speed

Limb position signals, ones that originate inside skeletal muscles, race toward the brain at up to 390 feet per second. To see this in action, close your eyes and wave your arms in the air. You know instantly where your arms are in space, although you cannot see them.

Touch signals move as fast as 250 feet per second. Bringing up the rear are pain and temperature signals; they move as slowly as 2 feet per second. This disparity explains why there is a delayed sensation of pain when you stub your toe.

To see how temperature lags behind touch, place a metal spoon on top of your bare foot. You will sense the touch of the spoon before you feel its coolness. However, if you place the spoon in the freezer for a few minutes and then try the same experiment, you will find that the touch and cold sensations arrive at almost the same instant because intense temperature sensations move nearly as fast as touch does.

Vision signals also vary according to intensity. For example, you will react more slowly to a punch in a dimly lighted area than you would in brightly lighted area.

When you know you are being testing on reaction time, tests show the average reaction time is between 150 and 250 msec. (milliseconds). Under usual testing conditions, typical subject has a mean auditory reaction time of about 140 msec. and mean visual reaction time of about 180 msec. Reaction time for touch is sometimes as short as that for sound, sometimes perhaps 25 msec. longer. The minimum reaction time achievable seems to be about 110 msec.