It follows the Sustained Attention to Response Task (SART) used in attention research: digits from 1 to 9 flash past, and you press for every digit except 3. Pressing is easy — the hard part is withholding your response when the 3 appears, which only happens if you're genuinely paying attention.

Accuracy of 90% or higher over the two minutes is a strong score; 96%+ is excellent. Most mistakes are presses on the forbidden digit — they show your responses have gone onto autopilot, which is exactly what the test is designed to catch.

Treat each digit as a fresh decision rather than settling into a pressing rhythm. More broadly, regular sleep, exercise, breaks from screens, and single-tasking measurably improve sustained attention over time.