methodological curiosity (Score 1)

Sorry to be picky, but since Posit Science claims millisecond resolution on their measure, I'm curious as to how their timing routine works. I realize that how fast a person clicks doesn't matter:

Note: You can take your time responding. It does not matter how fast you click your mouse.

However, as a response-time-oriented cog sci guy (not a neuroscientist), I know that there are two issues with timing routines. First, if the experimental control program uses the system timer then you only get 55ms precision. Second, and more difficult to handle, is the problem of having many participants running multitasking environments (Windows). Thus, whatever processes are running in the background could affect the precision of your measure. Then again maybe you have some ingenious way of controlling for these problems due to the fact that how fast the participant clicks does not matter. I know that I would be interested in doing my experiments online if I didn't have to worry about these issues.