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Reaction time


One definition of reaction time is the interval between some signal (one that demands a response from you) and the initiation of your response. It takes time for nerve signals to reach the brain and be processed. If you stub your toe, you know it should hurt but it does not hurt for a second. Then it hurts; it hurts a lot.

Signals from different sensory systems get to your brain at different times. The fastest are signals that relay muscle position. Next are the signals that relay the sensations of touch and vibration, followed by signals relay the sensations of pain and temperature. The evolutionary significance of this variation is unclear, but one theory holds that position and touch arrive earliest because they coordinate movement.

Signal speed

Arm and leg 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 move 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 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 a brightly lighted area.

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

Reaction time variables

Reaction time may be affected by strength or complexity variables, Reaction time may be shortened by “strength” conditions, but not below an irreducible minimum. Reaction time may be lengthened by “complexity” conditions

Strength variables

These are variables that affect some part of the chain of processes between the signal and its response, such as:
  • Intensity of signal. The more intense the signal is; the shorter is the response time and vice versa. For example, you react faster to a loud signal than you do to a quieter signal.
  • Discrimination. The more different the signals are, the shorter the reaction time. For example, you react quicker to backfire than you do to a bright flash of light.
  • Motivation. Motivation affects reaction time. For example, you react to a punch quicker when you are sparring full contact than you do when you are sparring no contact. The prospect of pain is a greater motivator.
  • Preparation. If a warning signal is given a second or two before the signal for response, the reaction time is shortened. For example, reaction time after seeing a fist cocking just before a punch will be less than the fist punching without cocking.
  • Practice. Reaction time may be decreased by practice, especially for complex conditions. More example, the more you spar, the faster you react to attacks.

Complexity variables

Complexity is anything that changes the situation on each trial, but uses the same signal and requires the same response, such as:
  • Multiple options. Where there is a choice of reactions depending on the signal, reaction time increases. For example, a punch only requires you to block the upper body, but a kick may require you to block either the upper or lower body.
  • Indirectness. Any introduction of indirectness or incompatibility between signal and response will increase reaction time. For example, a slight movement of the left fist may increase your reaction time to a right cross.
  • Prior involvement. If there is an unpredictable succession of two signals, each requiring a response, reaction time to the second signal may increase. For example, it requires more time to react to a combination attack than to a single attack.


The main thing to learn from this discussion is that reaction time may be decreased through practice. If you have ever sparred with highly experienced fighters, they seem to be bored while sparring with you. However, they react so quickly to your attacks that it seems as if they are reading your mind and reacting before you even move. The years of practice have honed their reaction time down so far that their reaction to an attack appears instantaneous. If you want to react quicker, you must practice reacting quicker.

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