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Correcting for Mac Triple Buffering

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#1

Hello,

My lab has collected some data with PsychoPy on a Mac OS 10.13. Recently we became aware of the triple buffering issue on new macs that causes a stimulus presentation delay of one screen refresh. We are trying to decide how to best correct for this delay.

I’m unclear if this lag is also affecting stimulus duration. In other words, I’m not sure if the experiment as a whole is just pushed back 16.66 ms leaving relative onsets intact, or if there is an additional 16.66 ms being added to each stimulus duration.

Can anyone confirm whether or not the triple buffering issue will affect stimulus duration?

#2

If your display is running at, say, 60 Hz, then PsychoPy will be feeding frames into the “pipeline” at that rate. The initial frame will be displayed late in absolute terms, but the relative timing between subsequent frames should be preserved, because a new frame will still be displayed every 16.66 ms.

#3

Thanks for the clarification!