Psychomotor Vigilance Test (PVT)

What this test measures

The Psychomotor Vigilance Task (PVT) is the standard laboratory measure of sustained attention and alertness, widely used in sleep and fatigue research. A counter appears at random intervals and you respond the instant you see it. Your score is your mean reaction time across the session; lapses — responses slower than 500 ms — reveal momentary failures of attention.

How to play

Watch for the timer. The moment it appears, click as fast as you can and it shows your reaction time. Do not click early: anticipations are flagged as false starts. Twelve trials at unpredictable intervals make up one session.

How to improve

• Run the PVT at the same time of day to track changes in alertness.
• Lapses climb with sleep debt — it is a sensitive fatigue gauge.
• Wait for the timer to actually appear; do not anticipate it.

Frequently asked questions

What does the PVT measure? Sustained attention and alertness — how consistently fast you respond over time, and how often your attention lapses.

What is a lapse? A response slower than 500 ms. Lapses increase with fatigue and sleep deprivation.

Is lower better? Yes — a lower mean reaction time, and fewer lapses, is better.