Reaction Time Test

Simple reaction time is the shortest time a person needs to respond to a signal they are already waiting for: one stimulus, one response, no choice to make. Francis Galton was measuring it in the 1880s, and it has stayed in use ever since as one of the most basic measures of how quickly the nervous system processes information. Roughly half of a typical reaction is spent noticing the signal and the rest is spent getting the movement out: in a large calibrated study, detecting the stimulus took about 131 milliseconds on average, whatever the person's age.

This version follows the standard design. Each trial starts with a wait of between one and a half and four seconds, chosen at random so the moment cannot be predicted. The panel then turns green, and the browser's high-resolution clock runs from the frame in which the green is drawn to the moment your press registers. A response faster than 110 milliseconds is counted as a false start, because no one genuinely reacts to a visual signal that quickly, and a response slower than one second is treated as a lapse of attention. Both are run again, so your result is always the average of five valid trials.

Every measured reaction time includes the equipment as well as the person. A screen takes some milliseconds to display the change, and a mouse, keyboard or touchscreen takes some more to report the press. Researchers who calibrated their equipment carefully found that a monitor and a gaming mouse added about 18 milliseconds between them. A web page adds more: when one study timed web pages with a robot finger and a light sensor, reaction times came out about 58 to 70 milliseconds too long on phones and 62 to 133 milliseconds too long on laptops, depending on the device and the browser. Touchscreens were no slower than keyboards in that study, but the spread between devices was wide, so the fairest comparison is between results taken on the same device.

Your result is compared with the Deary-Liewald reaction time task, which was run on an ordinary desktop computer, the kind of setup closest to this test. Its 150 adults, aged 18 to 80, averaged 274 milliseconds, with a standard deviation of 49. The young adults were quickest, with a median of 243 milliseconds; the middle-aged group's median was 281 and the over-sixties' was 287. The five bands on your result are set around that sample: averages between 250 and 300 milliseconds are typical, faster ones are fast or very fast, and slower ones are slower than typical or slow. On a phone the test switches to its phone version, which is tapped rather than clicked. No comparable sample of adults timed on phones has been published, so phone results are set against the same computer sample, and your result says so.

Age is the most reliable influence. Simple reaction time slows by about half a millisecond a year through adulthood, and the slowing comes almost entirely from producing the response rather than from detecting the signal. Alertness matters too: tiredness, distraction and a wandering mind all lengthen reactions and make them more variable from one trial to the next. Practice helps a little, because it trims the uncertainty about when to move, and many people find their second attempt slightly faster than their first.

This test is a quick measure of how you are reacting today, on your device. It is not a medical or driving assessment, and a slow result on one sitting says more about the moment than about you. If you want a steadier figure, take it a few times on the same device and look at your typical result rather than your best one.

References

• Deary, I. J., Liewald, D., & Nissan, J. (2011). A free, easy-to-use, computer-based simple and four-choice reaction time programme: The Deary-Liewald reaction time task. Behavior Research Methods, 43(1), 258-268.
• Woods, D. L., Wyma, J. M., Yund, E. W., Herron, T. J., & Reed, B. (2015). Factors influencing the latency of simple reaction time. Frontiers in Human Neuroscience, 9, 131.
• Neath, I., Earle, A., Hallett, D., & Surprenant, A. M. (2011). Response time accuracy in Apple Macintosh computers. Behavior Research Methods, 43(2), 353-362.
• Pronk, T., Wiers, R. W., Molenkamp, B., & Murre, J. (2020). Mental chronometry in the pocket? Timing accuracy of web applications on touchscreen and keyboard devices. Behavior Research Methods, 52(3), 1371-1382.

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