I could - and still can - make a pretty damn good estimation of a CRT monitor's refresh rate. I can distinguish between 60Hz, 80Hz and 100Hz with reasonable acc

I could - and still can - make a pretty damn good estimation of a CRT monitor's refresh rate. I can distinguish between 60Hz, 80Hz and 100Hz with reasonable accuracy (in steps of about 20Hz). Also, anything below 80Hz gives me terrible headaches.