Above the 75th percentile
Choice reaction is simple reaction plus a decision: the stimulus has to be noticed, identified, and answered on the right side. The gap between the two is what this scale measures; Hick described it as a logarithm of the number of alternatives, and with two alternatives the surcharge usually lands somewhere around seventy to a hundred milliseconds. The top of the scale is where that surcharge is small, not where the hand is fast. Which has a practical consequence: you cannot win here by pressing early. A wrong side costs a second and a half of penalty, and one of those eats the gain from all eight trials. The top belongs to people who do not guess.
Middle: 25–75
Three hundred to four hundred and fifty milliseconds is the ordinary zone, and it is made of three pieces that feel like one: see, identify, move. What shows up most in this zone is not the person but the hardware. A wired mouse and a 120 Hz screen against a touchscreen and 60 Hz is a difference of several tens of milliseconds — half a band of this scale — and the test cannot subtract it. The other thing that moves the score: the median is taken over eight trials, so one fumbled trial barely matters while an even tempo does. What wins here is the absence of dropouts, not a burst.
Below the 25th percentile
Five to six hundred milliseconds is the bottom of the scale, and before reading it as slow it is worth subtracting the equipment. A touchscreen, a trackpad, a Bluetooth mouse, a 60 Hz panel, a laptop in power-saving mode — each adds its own milliseconds, and together they add up to more than the spread between people. Then there is strategy: if you waited for full certainty before pressing, you traded speed for accuracy, and this scale cannot tell that trade apart from slowness. One session, one device, one minute; the number says nothing about the health of your nervous system.