What is simple reaction time?
Simple reaction time (SRT) is the elapsed time between the appearance of a single, expected stimulus and the subject's physical response — typically a button press. It is the most fundamental measure of neural processing speed.
The key word is simple: there is one possible stimulus and one possible response. No decision is required. This isolates the pure sensory-motor processing chain — from photon hitting your retina to finger moving — without the added complexity of choosing between options (which is called choice reaction time).
| RT Type | Stimuli | Responses | Typical avg |
|---|---|---|---|
| Simple RT | 1 | 1 | ~250ms |
| Recognition RT | Several | 1 (match/no-match) | ~400ms |
| Choice RT | Several | Several | ~500ms+ |
The Human Benchmark Reaction Time test measures simple visual RT. The green screen is your single stimulus; clicking is your single response. The randomised delay before the green prevents anticipatory responses.
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Quick Answer
Simple reaction time is the time between a single expected stimulus (like a green light) and your physical response. It is the purest measure of neural processing speed.
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