refresh rate and stimulus duration

Allen_Ingling · June 26, 2010, 10:59pm

Hi, I've been using VBLTimestamp to test the duration of my stimulus presentations (with timeX=Screen('Flip',when) ). Using the vblTimestamp when I flip my stimulus 'on', and the vblTimestamp when I flip my stimulus 'off', I've found that the recorded presentation duration isn't roughly divisible by 16.67 (the refresh rate of my monitor, from ScreenTest). So, I'm confused as to what I'm measuring - I thought 'Flip' went into effect on the first screen refresh after the 'when' argument has been passed. Am I wrong here, or is there a problem with my computer's timing?

Thanks!
Cynthia

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refresh rate and stimulus duration

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