Choice vs simple reaction
Simple reaction time tests one stimulus and one response — click when green. Choice reaction tests multiple possible stimuli and a unique response for each. The difference is your brain’s decision overhead, which usually adds 100–200ms.
Why this matters for gaming
Real games rarely give you a single stimulus to react to. You’re identifying what’s on screen, deciding between options (peek vs hold, shoot vs reload, dash vs block), then executing. Choice reaction is a closer proxy for that workflow than simple reaction time.