Reaction time measures the elapsed duration from the presentation of a sensory stimulus to the beginning of a motor response. It reflects the speed of neural processing across perception, decision-making, and motor execution pathways.
How Reaction Time Is Measured
Reaction time is typically assessed using simple or choice paradigms. In a simple reaction time task, a single stimulus requires a single response - such as pressing a button when a light appears. Choice reaction time involves selecting among multiple responses based on different stimuli. Laboratory measurements use millisecond-precision timers. Computer-based measurements can include timing delays introduced by hardware and software.
Factors That Influence Reaction Time
Several variables affect reaction time, including age, fatigue, arousal level, stimulus intensity, and practice. Reaction time lengthens with age, and one study reported that the age-related increase in simple reaction time is due primarily to slowed motor output. Sleep deprivation, alcohol, and certain medications slow responses.
Practical Applications
Reaction time benchmarks are used in sports science to evaluate athlete readiness, in clinical settings to detect neurological impairment, and in human factors research to design safer interfaces.