Reaction Time

In cognitive psychology, reaction time (RT) is used to measure the amount of time that it takes an individual to process information (Luce). It is the duration of the interval between presentation of a stimulus (e.g., a word on a computer monitor) and the participant’s response to the stimulus. RT is considered to be a dependent variable because it ‘‘depends’’ on the manipulation of an independent variable (such as the exposure duration of a stimulus). RT is related to response accuracy (the other primary dependent variable in cognitive psychology), because participants can often trade off speed for increased accuracy, or conversely, trade off accuracy for increased speed (Pachella). It is important to note, though, that accuracy and RT are often used for different purposes. Accuracy tells us whether a series of perceptual and mental processes is completed correctly. RT is used to infer process duration.