Red Light Green Light Reaction Test
Run on green, freeze on red. Miss the stop and you’re caught.
MEASURES
Go & stop RT
INPUT
Hold / release
TIME
~60 sec
How the test works
Stopping is harder than starting
Nearly every reaction test measures how quickly you can act. This one measures how fast you can stop, releasing a held action the moment the signal changes. Halting a movement already in progress calls on a different brake in the brain, and it usually runs a touch slower than starting one.
It makes a natural pair with the Go / No-Go test, which measures withholding an action you never started. Between them they cover the two halves of impulse control.
How your score grades
Instant brake
under 260 ms
Exceptional stop reaction — hard to beat
Sharp
260 – 329 ms
Quick to freeze — better than most
Average
330 – 399 ms
A typical stop reaction
Slow to stop
400 ms +
Anticipate the red a little earlier
Questions
Why measure how fast I stop?
Halting an action already underway is a distinct skill from starting one, and hardly any test measures it. Releasing a held movement draws on the brain's inhibitory system, which usually runs slightly slower than initiating a movement.
Why is my stop reaction slower than my click reaction?
Stopping a movement in progress generally takes a little longer than starting one, since your brain must override an action it has already committed to. A stop time somewhat above your simple click reaction is entirely normal.
What gets me caught?
Holding for too long after the light turns red. The window to release is short, and missing it costs you a life. Three misses and the run ends before the finish line.
How is this different from Go / No-Go?
Go / No-Go is about withholding an action you never began. This is about cancelling an action already in motion. Between them they cover both sides of impulse control.