⏱️ Methodology

How is reaction time measured?

Reaction time is measured as the interval between stimulus onset and response registration. The precision of this measurement depends heavily on the hardware and software used.

Online measurement (Human Benchmark method)

Stimulus trigger
JavaScript schedules the green screen after a random delay using setTimeout()
Timer start
performance.now() is recorded at the exact frame when the stimulus renders
Response capture
mousedown / keydown event fires; performance.now() is recorded again
RT calculation
Response timestamp − Stimulus timestamp = raw RT
Latency caveat
Display refresh lag (8–16ms on 60Hz) and input polling lag are not subtracted

Lab-grade measurement uses dedicated hardware timers with microsecond precision and controlled display hardware (often a CRT at 1000Hz refresh rate). The difference between lab and online measurement can be 15–30ms — which is why online scores are useful for relative comparison and trend-tracking but not direct comparison to clinical studies.

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