Reaction Time

Generally, in psychological measurement, the interval of time between the presentation of a stimulus to a subject and the beginning of the subject's response to that stimulus.

Several categories of reaction time, such as simple reaction time, have been established and studied in experimental psychology. In a simple reaction time experiment, the subject is presented with one simple stimulus, such as a light, and instructed to perform one simple response, such as pressing a button. In a discrimination reaction time experiment, the subject is presented with one of two or more different stimuli, such as a red light and a green light, and instructed to perform a response to only one of the stimuli, such as pressing a button when the red light is presented but not when the green light is presented. In a choice reaction time experiment, the subject is presented with one of two or more different stimuli, such as a red light and a green light, and instructed to perform different responses depending upon which stimulus is presented, such as pressing a red button when the red light is presented and pressing a green button when the green light is presented. There are other types, and many variations of reaction time experiments.