Don't forget: For fastest results, press start, then press and hold
the stop button. Release the hold when the background changes color.
Also, I've noticed that CRT monitors produce faster times (about .05 - .10 seconds faster) than LCD monitors. That's simply because CRT's pixels are faster to change the background color than LCD's. So if you can do anything in the .30 - .35 second range with an LCD, you have average reflexes. If you have a CRT, you should be shooting for .25 - .30 seconds.
Feel free to bookmark the reaction time tester
page, as I've had it up for 8+ years, and plan on leaving it up. I like to test my reflexes as I grow older.