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1Scan for outdated or missing drivers - takes under a minute2Clear out junk files and repair common Windows errors3Fix the driver behind crashes, sound loss and screen glitchesA reliable reaction-time test starts by defining what each input does in each phase—and exactly which two events the displayed time measures. Model the test as a small state machine, reject early responses as false starts, and show users the limits of browser timing. This is an interaction demo, not a clinical assessment.
How do I make a reaction time test?
Represent the test with explicit states: idle, waiting, ready, result, and finished. Each event has one defined effect in the current state. A start action begins a trial; an early response is rejected; the first valid response ends the trial. Update the stored data and visible feedback together so users can tell what happened.
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| Current state | Event | Next state | Behavior |
|---|---|---|---|
| idle | Start | waiting | Initialize the session and schedule a randomized delay. |
| waiting | Click or key press before the cue | waiting, or a dedicated false-start state | Record a false start, not a reaction duration, and explain whether the round will retry or be consumed. |
| waiting | Delay completes | ready | Present the cue and record the chosen cue-onset timestamp. |
| ready | First valid response | result | Capture the response once, calculate elapsed time, and reject duplicate responses. |
| result | Continue; rounds remain | waiting | Reset per-trial data and schedule the next delay. |
| result | Last round complete | finished | Show the session summary; retain individual observations if the tool is used for research. |
This is a design pattern, not a state model required by a standard. Decide whether a false start retries the same round or consumes a trial, then apply that policy consistently in the interface and stored data. Disable controls that do not apply in a state, or ignore their input without implying it was accepted. Pointer and keyboard input should follow the same rules.
Keep the transitions small and explicit
Keep per-trial values—such as cue time, response time, and false-start status—separate from session-level values such as the current round and trial history. When a transition occurs, change the state, update the relevant data, and render the corresponding message as one operation. Guard against stale timers: a delay scheduled for an old session must not make a reset or newly started session enter ready.
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How should I handle a click before the signal?
Treat it as a false start, not as a fast score. While the test is in waiting, no valid cue has occurred, so there is no valid cue-to-response interval to report. Give the user immediate feedback and follow the trial policy you chose: retry the round or count it as consumed. Make the same policy visible in any exported data.
Randomizing the delay makes the cue less predictable. In the Reflex research tool, one implementation uses a randomized wait of one to three seconds and restarts the round after a click during that wait. That interval and retry behavior are examples, not universal standards; choose and disclose a policy suited to your use.
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What does the reaction-time number measure?
Define the measured interval as the elapsed time between a specific cue event and a specific input event. For browser code, performance.now() provides a high-resolution, monotonic time basis suited to elapsed-time calculations; it is not a calendar clock. The W3C specification also notes that browsers may reduce timing precision for security and privacy reasons. W3C High Resolution Time
For a visual cue, the moment your code decides to change the page is not necessarily the moment a changed frame appears on the screen. requestAnimationFrame() schedules a callback before the browser’s next repaint and provides a frame timestamp, so it can align a visual update with the rendering cycle. It does not report when the display panel physically emitted the cue. The compositor, display response, and scanout are outside the ordinary page’s direct observation. MDN: Window.requestAnimationFrame()
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- Indicator Lights: Power On: White light; Red light: Indicates the transmitter and receiver are aligned and a human body has been detected; Green light: Indicates the user is jumping during training.
- Data: Supports saving and exporting records; Positioning accuracy: ±1 cm; Operating frequency: 1000 Hz; Usage: Offline or via APP
- Power Switch: Type-C charging, 8-hour battery life, easily handling long training sessions. This product is a portable power switch and does not have an automatic shutdown function; manual power on/off is required during use.
- Assembly and Use: Align and insert the device according to the interface. Place the device on a flat surface, maintaining a distance of 1-2 meters between the device and the receiver, with 1.5 meters being the optimal distance. This avoids insufficient detection range due to being too close or unstable infrared signal due to being too far away.
- service: we value our customers' shopping experience. if you have any questions, please feel free to contact us, and we will respond as soon as possible within 24 hours
Browser-based stimulus timing can vary with browser, operating system, GPU acceleration, and visual technique. A 2018 study by Garaizar and colleagues recommends validating the exact setup when a one-frame deviation matters; its historical browser combinations do not establish performance for current systems. Garaizar et al., “Best practices: Two Web-browser-based methods for stimulus presentation in behavioral experiments with high-resolution timing requirements”
A suitable disclosure is: “This score is the elapsed time observed by this browser between the test’s defined cue event and your input event. Your device and display affect it; it is not a clinical measurement.” Do not add a universal lag correction or precision beyond what the clock and rendering path support.
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How should I present results?
For a multi-trial casual test, show valid attempts and label any summary statistic, such as the mean or median. State the number of trials, whether false starts consume a round, and which attempts the summary includes. Showing only a best score hides variation and rewards repeated attempts, so it should not stand in for a session result.
For research, preserve the trial sequence rather than only a summary: valid and rejected responses, protocol version, and relevant browser and device context. Specify exclusions and the analysis method before interpreting group differences. The cited sources do not establish one universally correct summary statistic.
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- 【Easy Single-Tap Operation with Adjustable Audio Prompt】: One button controls power on/off and ℃/℉ unit switching; double tap to turn off the built-in audio prompt. The simple setup fits elderly users perfectly, and the quiet sampling mode avoids sound distractions during night use in bedrooms, offices and vehicles.
- 【High-Precision Sensor System & HD Large Display】Equipped with a high-precision sensor array, the unit automatically samples and processes air data every 1.5 seconds, delivering continuous, real-time updates on your indoor air conditions. The clear, high-definition color screen not only enhances readability with color-coded air level readings, but also adds a modern, professional aesthetic to your workspace or living area.
- 【Up to 4-5h Run-Time & Universal Type-C Fast Charging】: A full charge supports 4-5 hours of continuous air sampling. The standard Type-C port works with common mobile charging cables, and the package includes a matching AC power adapter and Type-C fast charging cable for convenient power replenishment. You can easily use it across home, car and indoor spaces without frequent charging.
- 【Portable Multi-Scenario Air Testing Device & Reliable After-Sales Service】: Compact and lightweight design supports flexible placement and handheld use, perfect for air parameter testing in indoor rooms, vehicles, bedrooms, offices, campsites and more. The package contains 1 air quality monitor, 1 Type-C charging cable, 1 AC power adapter and 1 user manual. We provide 12-month quality support for the whole unit, letting you enjoy worry-free long-term daily air testing.
Xu and Claypool’s 2025 paper describes Reflex as an open-source tool for measuring human reaction times and discusses configurable studies and raw-data output. Their reported sample of 300 participants, mostly gamers, averaged about 50 ms faster than general-population online-tool reports. That is a result for their pooled sample and comparison—not a population benchmark and not evidence that gaming caused the difference. Xu and Claypool, “Reflex – An Open-source Tool for Measuring Human Reaction Times”
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