Reaction time

Reaction time (RT) is the elapsed time between the presentation of a sensory stimulus and the subsequent behavioral response. RT is often used in experimental psychology to measure the duration of mental operations, known as mental chronometry. The behavioral response is often a button press but can also be an eye movement, a vocal response, or some other observable behavior.

Types of RT tasks

  • Simple reaction time is usually defined as the time required for an observer to detect the presence of a stimulus. For example, an observer might be asked to press a button as soon as a light or sound appears. Mean RT is approximately 180 to 200 milliseconds to detect visual stimuli, whereas for sound it is around 140-160 milliseconds.
  • Go/No-Go reaction time tasks require that the observer press a button when one stimulus type appears and withhold a response when other stimulus types appear. For example, the observer is to press the button when a red light appears and not respond when a green light appears.
  • Choice reaction time tasks require distinct responses for each possible class of stimulus. For example, the observer may be asked to press one button if a red light appears and a different button if a yellow light appears.


Abū Rayhān al-Bīrūnī was the first to describe the concept of reaction time:

Franciscus Donders was among the first to systematically analyze human RT to measure the duration of mental operations.

See also

Mental chronometry


External links

Simple Reaction Time Tests: (note that the hardware/software setup will greatly affect measurements making the scores largely incomparable from user to user)

Complex Reaction Time:

Simple Reaction Time:

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