What it does
Useful, focused capabilities
- Visual and four-arrow choice modes
- 3, 5, or 10 trial sessions
- Randomized delay and false-start handling
- Median, average, best, and variability
- No medical claims or fabricated percentiles
Skill & performance · browser-local
Reaction time test
Test reaction time locally with visual and choice modes, false-start handling, session median, variability, and private on-device history.
Work happens in the current browser. The route does not require an account or a server-side processing job.
Interactive browser workspace
Reaction time test
The live tool is loaded in this browser only. This route does not need camera, microphone, or screen-capture permission for its main task.
Open this local tool →Browser compatibility
Requirements and honest fallbacks
JavaScript and a modern browser; keep the tab visible and use pointer or keyboard input for meaningful timing.
- JavaScript
- pointer or keyboard input
- Local storage
Questions people ask
Clear answers and limits
Is this a medical reaction-time test?
No. It is a browser interaction test and cannot diagnose a neurological, attention, vision, or motor condition.
Why does the page cancel a hidden-tab trial?
Browsers can delay timers and rendering in hidden tabs. Cancelling protects the result from a known source of distortion.
Why use the median?
A median is less sensitive than an average to one unusually slow interruption or one unusually fast anticipated response.
What counts as a false start?
Any response before the signal, plus implausibly early responses below the conservative browser threshold, restarts the trial without saving a time.
Can I improve reaction time with this tool?
Repeated practice may improve familiarity with this exact task. The tool does not promise transfer to driving, sport, gaming, or clinical performance.