Recently, I've noticed several LCD computer monitors with stated specs that include a "pixel response time" as low as 5 mS. Be sure to note the difference between response time and refresh rate--I'll try to find a good link to the difference and post it here.
And as discussed in the thread Blair links to above...
Remember that refresh rate is the inverse of the frequency that images are displayed. For example, if you've set the monitor to 1024 x 768 at 60 Hz, the refresh rate is 1/60 or 16.67 mS. If the monitor supports 75 or 80 Hz, the refresh rate would be 1/75 or 1/80 (13.3 and 12.5 mS respectively).
So if you only want to present one frame of video to your subjects, the screen time would be 16.67, 13.3 or 12.5 mS.
-John