Reaction Time Test

How the Reaction Time Test Works

When the box turns green, a chain of biological events begins. Light reaches the retina, where photoreceptors convert it into electrical signals. These signals travel along afferent (sensory) neurons through the optic nerve to the thalamus and then the primary visual cortex at the back of the brain. Association areas recognize the change as your go signal, and the premotor and motor cortex plan the movement. A command then travels down efferent (motor) neurons through the spinal cord to the muscles of your finger, which contract and press the button. Every step adds delay, and together they typically take about 200 to 250 milliseconds for a simple visual stimulus.

What the timer actually measures

TapReflex starts its clock with the browser's high-resolution performance.now() timer on the first screen frame that shows green, and stops it the moment your pointer goes down. Because the random wait is 2 to 5 seconds, you cannot predict the signal, and tapping early counts as a false start. A single attempt can vary by 20 to 30 milliseconds from natural fluctuation in attention, so the test averages five rounds for a more stable number.

Reaction Time Benchmarks

Simple visual reaction time depends on age, practice and equipment. Browser tests add display and input latency, so these are typical web-test ranges rather than laboratory values.

How age changes reaction speed

Processing speed peaks in the twenties and declines slowly afterwards as nerve conduction and cognitive processing slow. The change is gradual and varies greatly between people, and regular exercise, good sleep and mental activity are associated with smaller losses. Athletes show the other end of the range: in sprinting, a reaction to the starting gun faster than 100 milliseconds is treated as too early to be a genuine reaction and is ruled a false start.

Hardware Latency Factors

Monitor refresh rate

A 60 Hz screen redraws every 16.7 ms, a 144 Hz screen every 6.9 ms and a 240 Hz screen every 4.2 ms. The green signal can only appear on the next redraw, so a 60 Hz display adds about 8 ms on average and up to 17 ms in the worst case, compared with about 3 ms and 7 ms at 144 Hz. Read the full analysis in our refresh rate guide.

Mouse polling rate

A mouse reporting at 125 Hz sends an update every 8 ms, at 500 Hz every 2 ms and at 1000 Hz every 1 ms. Wired or high-quality wireless mice at 500 to 1000 Hz keep this delay negligible, while a budget Bluetooth mouse can add noticeably more.

Input lag, browsers and operating systems

TVs without game mode, V-Sync buffering, power-saving CPU states and many background browser tabs can each add a few milliseconds. For comparable results, use the same device, a wired mouse, game mode and a quiet browser every time.

Tips for an Accurate Result

1. Close other tabs and apps, and plug in laptops.
2. Use the same mouse or touchscreen between sessions.
3. Do at least three full 5-round sessions and compare averages, not single taps.
4. Test when rested and at the same time of day to compare progress fairly.

Frequently Asked Questions