Guide
F1 start lights guide
The timer uses a five-light sequence to create the same basic pressure as a race start: wait while the red lights appear, then react when they go out.
How the sequence works
Each light column turns on in order. Once all five are lit, the timer waits through a random delay before switching to lights out. Your reaction time begins at lights out and stops on your first valid input.
Why the delay is random
A fixed delay would reward memorizing the rhythm. The random lights-out delay makes the test about responding to the signal rather than predicting it.