This is a Javascript reaction time tester. Created by Terry Sturtevant . Comments welcome. Page last updated Friday May 12, 2017
led display



Anticipated event
Random event
Synchronized event




There are two different kinds of events to which people must react; random events and anticipated ones. This tester allows a person to test both. It also allows people to test how well they can synchronize with each other. In both tests, once the "start" button is pressed, after a certain delay all three dots will be red. The objective is to press the "stop" button at the instant the dots all turn red. (There are actually two stop buttons which can be used. One registers the time when the button is pressed, and the other registers the time when the button is released. Either one can be used.)

For the anticipated event test, at fixed intervals the dots will turn red individually before they all change, and the interval from the bottom dot changing to all three changing is identical to the other intervals. The fixed interval can be changed.

For the random event test, boundaries for the random interval can be changed as well. It is possible for a reaction time to be negative for the anticipated test, but for the random test a negative time is simply a wild guess.

In either case, (random or anticipated), activating the "stop" button before all three dots go red will be indicated by only the lowest dot being red.

To test synchronization, one person, (the "initiator") uses the keypad and the other (the "responder") uses the mouse. In synchronized mode, once the start button is pressed, the dot sequence will advance each time a key is pressed on the keyboard. The goal is for the responder to click the "Stop" button at the same instant as all of the dots turn red. Positive and negative times are both possible, as for the anticipated event test. As in the other tests, activating the "stop" button before all three dots go red will be indicated by only the lowest dot being red.
Note: In synchronized mode, the initiator should use letter or number keys, rather than the enter key, spacebar, etc. as those may result in strange behaviour.

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Wilfrid Laurier University