Disclaimer. Browser response times depend on your screen, input device and system load. They are labelled device-dependent and are not a medical measurement. Full disclaimer

Reaction Time

Respond the moment the panel lights up.

Start testAbout 2 minutes · demo and practice first

What it measures

The time between a visual cue appearing and your response, as measured by your browser. Your result is the median of ten valid responses.

DurationAbout 2 minutes

Format3 practice trials, then 10 valid trials

Device and setupKeyboard (Space) or one touch target. Input lag differs between devices.

Accessibility limitsRequires seeing a colour and brightness change and responding quickly with one key or tap.

Free resultMedian response time in milliseconds

PrivacyYour answers are never sent to advertisers. Signed in, your results are saved to your account.

How it is scored

Your score is the median of ten valid responses. Responding before the cue is a false start. Times under 100 ms or over 2000 ms are excluded. After 20 attempts without ten valid ones, no score is given.

Starter content, version 1. Difficulty is provisional until pilot data supports it. Full methodology

What Premium adds

Interquartile range, trial chart and false start review. One upgrade covers all ten tests. See Premium

Limits

Browser response times depend on your screen, input device and system load. They are labelled device-dependent and are not a medical measurement.

For education, entertainment and general self-exploration only. These activities are not medical or psychological assessments and do not diagnose, prevent or treat any condition. Results are estimates of performance on these tasks and can be affected by practice, attention, language, your device and your surroundings. If you have concerns about your thinking, vision or hearing, consult a qualified healthcare professional.