[visionegg] Re: working code for fMRI exp: comments please

  • From: Andrew Straw <andrew.straw@xxxxxxxxxxxxxxx>
  • To: visionegg@xxxxxxxxxxxxx
  • Date: Sat, 3 May 2003 23:20:49 -0600


Christoph Lehmann wrote:

Hi

Here the code (main loop) of a small visionegg project, which waits for
a trigger on the parallel port, after a received trigger it updates the
screen with the next stimulus, and all mouse-responses are logged in a
file with the RT (relative to the actual stimulus). Also all stimuli are
logged into a file with stimulus-name and onset-time

What do you think about the timing-quality?

Without running it, it looks great.

(snip)

Andrew, if I sync buffer-swapping: does the swap_buffers() code wait for
the vsync pulse, and therefore during this time I will have an
unprecision in the RT?

The swap_buffers() code does wait for the vsync pulse before returning, but the VisionEgg.time_func() still returns a precise time. So, your measure of response time should be as accurate as possible, particularly because you are not swapping buffers while waiting for mouse presses.

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