What Is a Reaction Time Test?
A reaction time test measures the interval between a stimulus appearing and your physical response. In this test, you wait for the screen to change from red to green, then click as fast as possible. The time between the color change and your click is measured in milliseconds.
Reaction time is one of the most fundamental measures of cognitive processing speed. It reflects how quickly your brain can detect a stimulus, process the information, decide on a response, and send the motor command to your muscles.
Average Reaction Time by Age
The average reaction time for young adults (18-30) is approximately 230-270 milliseconds for visual stimuli. Reaction time peaks in the mid-20s and gradually increases with age. Professional athletes and competitive gamers often achieve reaction times of 150-190 milliseconds through extensive practice.
Children typically have slower reaction times of 300-400ms, which improve through adolescence. By age 60, average reaction time increases to roughly 270-320ms, though regular exercise and cognitive training can help maintain faster response speeds.
Factors That Affect Reaction Time
Several factors influence how fast you can react. Sleep deprivation is one of the biggest impairments — getting fewer than 6 hours of sleep can slow reaction time by 20-30%. Caffeine in moderate amounts (100-200mg) can improve reaction time by 5-10%, though excessive amounts may cause jitters that worsen performance.
Physical fitness, hydration, and stress levels all play significant roles. Regular aerobic exercise has been shown to improve reaction time by an average of 10-15%. Dehydration of just 2% body weight can measurably slow cognitive processing speed.