Sequence Reaction Test
Four pads, one lights up — tap the lit pad as fast as you can. This measures choice reaction time, which is typically 50–100 ms slower than simple RT because your brain has to decide which pad to tap.
Tap a pad anywhere to start. One of the four pads will light up — tap the lit pad as fast as you can. We do 12 rounds and average your times.
Choice reaction time, explained
The simple reaction time test on the homepage measures exactly one thing: how fast you respond to a single stimulus with a single response. There is no decision. Green appears, you click. That is it. Choice reaction time is different — you have multiple possible stimuli and multiple possible responses, and you have to pick the right response for the stimulus you see.
This test uses four pads. One of them lights up at random, and you have to tap the lit one. That means your brain has to do three things instead of one: detect that a stimulus appeared, identify which of the four pads lit up, and route the motor command to the correct response. Each of those steps adds time. The result is that choice RT scores run about 50–100 ms slower than simple RT scores for the same person on the same hardware.
Hick's Law and why more choices slow you down
In 1952, a psychologist named William Hick ran a series of experiments varying the number of response options from 2 to 10. He found that reaction time increases linearly with the logarithm of the number of choices. Double the number of choices and you add a fixed amount of time; double it again and you add the same amount again.
This finding — now called Hick's Law — has held up across decades of replication. It explains why emergency vehicle dashboards have a few large buttons rather than a touch screen with menus: when you are choosing under time pressure, every extra option costs you about 100 milliseconds. It also explains why fighting game players spend hours memorising frame data — the less they have to think about which button to press, the faster they can press it.
For this test, four choices means you should expect scores roughly 80–100 ms slower than your simple RT. If you score 250 ms on the simple test, expect 330–350 ms here. If you score 200 ms on simple RT, expect 280–300 ms here. The exact gap depends on how quickly you can map "lit pad on the left" to "tap with left hand".