Visual Reaction Speed

How it works

Visual Reaction Speed measures how quickly you respond to a simple visual signal. The screen waits for a random delay, then flashes white. Your job is to press space or click as soon as the flash appears.

Brain systems involved

This test starts with vision. The signal goes from the eyes through the lateral geniculate nucleus, a visual relay in the thalamus, and then to the visual cortex at the back of the brain. From there, attention systems help decide that the flash matters, and motor areas help prepare and trigger the key press or click.

So the score is not only eye speed. It also depends on alertness, attention, decision speed, motor readiness, and how consistently you avoid early clicks or lapses.

Score guide

Lower is better. Around 180-220 ms is very fast. Around 220-280 ms is a normal strong range. Scores above 300 ms can happen when attention drops, timing feels off, or the device/browser adds delay. Responses below 100 ms are treated as anticipations, and responses at 500 ms or slower are counted as lapses.

What can change it

Sleep, caffeine, stress, fatigue, practice, keyboard or mouse latency, display refresh rate, and background browser activity can all change the result. Median score is used because it is less distorted by one unusually slow or fast trial.