Re: capturing user reaction times in msecs
Re: capturing user reaction times in msecs
- Subject: Re: capturing user reaction times in msecs
- From: Horst Hösel <email@hidden>
- Date: Tue, 19 Dec 2006 17:14:33 +0100
It's rather hard to know to ms precision when the display change
actually
becomes visible. Everything is double-buffered and the system
generally
updates the display on its own notion of when it "should", and of
course in
the worst case some displays (60Hz interlaced) may take as much as
~30ms to
complete display of the new image.
I don't know if there's a way to find out accurately when the updated
display is actually flushed to the device. I've asked this question
myself
before, and got no answer.
Recently I learned that modern displays might take 3 full screen
refreshes to show a change. This has to do with the 'preloading' of
the pixels. That would mean an addititonal delay of 3 * 16.67 ms or
50 ms, regardless of what the OS let's you know.
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