Average human reaction time by sense
How fast people react depends on which sense picks up the signal. These are commonly reported figures for simple reaction time, where there is one signal and one response.
| Signal | Typical reaction time |
|---|---|
| Touch | About 150 ms |
| Sound | About 170 ms |
| Sight | About 250 ms |
Vision is the slowest of the three because the retina takes longer to convert light into a nerve signal than the ear takes with sound. The test on this page uses a visual signal, so expect a number in the 200s.
What happens in those 250 milliseconds
A reaction is a chain of steps. Light hits the retina. The signal travels to the visual cortex. The brain recognizes the change and decides to act. A command travels down the spinal cord to the muscles of your hand. The muscle contracts and the button goes down.
Each step takes time, and most of the total is spent in the brain, not in the nerves. That is why reaction time gets longer as soon as there is a decision to make.
Simple and choice reaction time
The test here measures simple reaction time. One thing happens and you respond in one way.
When there are several possible signals and each needs a different response, it is called choice reaction time, and it is slower. The relationship is described by Hick’s law: the time to decide rises steadily as the number of options grows. This is the reason a driver takes much longer to respond to a surprise on the road than to a light they are waiting for. Road engineers commonly allow 1.5 to 2.5 seconds for a driver to notice a hazard and begin braking.
What changes your reaction time
- Age. Fastest in the twenties, then a slow decline.
- Alertness. Poor sleep is one of the largest effects. Tired people are slower and far less consistent.
- Practice. Familiarity with a task trims the slow responses and tightens your average.
- Caffeine. A moderate dose gives a small but reliable improvement.
- Your device. Screens and input devices add their own delay, often 20 to 50 ms, so online results are slower than lab figures.
Measuring your own
Run the test at the top of the page. It takes five tries and reports the average, which is more trustworthy than a single click. For the full score guide and tips, see the main reaction time test page.