Reaction-time test

• Average reaction time: the mean o yer timed taps, in milliseconds (ms). A lower number is faster.
• Fastest tap: yer quickest single tap. Ae lucky tap says less than the average.
• Slow taps: taps slower than 500 ms. Sleep researchers ca these lapses o attention, an they become mair common efter short sleep [1].
• Early taps: taps afore the circle turned green, or under 100 ms, which is ower fast tae be a real response. They’re left oot o yer average.

The chart shawes lab averages by age. A browser reads slower than lab gear (see belaw), sae uise the chart for the pattern an compare yer nummer wi yer ain earlier runs.

Cite this page: Reaction-time test. Helibrain. 2026. https://helibrain.com/sco/reaction-time-test. CC BY 4.0.

Cite this page: Reaction-time test. Helibrain. 2026. https://helibrain.com/sco/reaction-time-test. CC BY 4.0.

1. Tap whan it turns green. Tap, click or press Space or Enter.

This is the same test as in the Helibrain app. The page starts the clock whan it tells yer browser tae shaw the green circle, an stops it whan yer tap comes in. Sae yer time includes yer screen's delay an yer mouse, keyboard or touchscreen delay, which a wab page cannae measure.

• Yer device. In lab checks, wab pages added 58 tae 133 ms tae ilk response, dependin on the device an browser [3]. E'en wi a lab-grade button, browsers added 8 tae 67 ms [7]. On a touchscreen yer finger maun travel tae the glass an aw, which added aboot 95 ms in ae study [6].
• Sleep. Efter a nicht wi nae sleep, or several short nichts, responses slow doon an lang lapses become common [1]. Lapse an speed measures pick this up weel [8].
• Time o day. Attention follows a daily rhythm. For somebody that sleeps frae 11 pm tae 7 am, reactions are slowest at nicht an in the early mornin, an better in the efternuin an early evenin [9].
• Caffeine. A major review fund that aboot 40 tae 300 mg o caffeine improves alertness, vigilance an reaction time [10].
• Alcohol. In a placebo-controlled trial wi 16 young men, alcohol that raised blood alcohol tae aboot 0.07% slowed simple reaction time by aboot 43 ms at its peak [11].
• Age. The gap atween the youngest an auldest groups in Figure 1 is aboot 21 ms. The study estimated that the extra time gangs intae startin the movement, no seein the signal [2].
• Practice. Simple reaction time hardly changes wi practice. In 48 adults tested ance a week for three weeks, the average moved by less than 3 ms [12]. Across 36 studies, fowk got a wee bittie faster on the second try, then levelled aff [13].
• Action video games. Regular action-game players responded aboot 11% faster than non-players, wi the same accuracy, maistly on choice tasks [14]. Maist o thae studies compared fowk that already played, sae the games micht no be the cause.

Cite this page: Reaction-time test. Helibrain. 2026. https://helibrain.com/sco/reaction-time-test. CC BY 4.0.

The test measures hou fast ye answer ae expected signal, juist noo, on this device. It disnae measure intelligence, fitness tae drive or ony health condition, an it isnae a diagnosis.

Device delay is the biggest limit: it is mair than the hale age gap in Figure 1, an it differs atween devices. That matters maist whan comparin ae person wi anither [3]. Sae compare yer nummer wi yer ain earlier scores on the same device an browser.

Ane meenit is a snapshot. Shorter versions o the PVT still detect loss o sleep, wi smawer effects than the 10-minute version [15]. If yer reaction time worries ye, for example efter an illness or a new medicine, speak tae a doctor.