A quick Google finds numbers from 250-280, with record reflexes as low as 110ms. I've done less than 180ms on a "hit the button after the light goes on" game at

A quick Google finds numbers from 250-280, with record reflexes as low as 110ms. I've done less than 180ms on a "hit the button after the light goes on" game at a science museum (hardware designed for it, so no built-in latency). 300ms is a good lower limit, though, if you take into account complex video processing and standard brain activity when browsing; when hitting a button when you're browsing, your brain isn't wound up and ready to react as quickly as possible. Getting that extra fast reaction really requires short circuiting some of the mental processing you'd normally do. I'm pretty sure I'm remembering 300ms from the cognitive science/UI classes I took in college. And don't forget the hardware lag in your own body. ;) The signal to click the button takes ~10ms to get from your brain to your fingers. When you think about things like sports where the accuracy of, say, releasing a ball when throwing it, needs to be in the 0.1ms range to hit your target, but your brain is actually giving the command 10ms before the ideal release time... Makes my brain hurt just contemplating how it works. Pro tip: Don't think about this while trying to throw a ball accurately.