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Psychopy and Visuastim MRI goggles: how to use right bit color depth ("16-bit"?)

Hi guys,

I am currently setting up a study where I need to present my stimuli via the VisuaStim goggles in the MRI scanner on a Windows 10 computer.

Currently, I’m able to run my experiment on the “control monitor”, but the goggles just flicker some gray screen every few seconds. Other users of the goggles have told me that is likely be due to using the wrong bit color depth. They use PsychToolBox and can make it work by running Matlab in “16-bit color compatibility mode” (via right click on Matlab-> properties -> compatibility mode -> something with color).

I suspect that I have to change the bits-per-channel (bpc)-attribute of my (Pyglet) Window-object. I set these to 8, [8, 8, 8] and [5, 6, 6] (since I think the 16 bits are spread over all 3 channels like that), but it didn’t help.

What I also find strange is that the specs in the original manual of the goggles says

Gray Levels: Up to 256 per primary color
(http://www.mrivideo.com/files/pdf/Manual-VisuaStim.pdf)

Which would actually suggest 8 bits per channel, 24 bits in total, no?

Would anyone of you have any experience with these goggles and/or old “16 bit” monitors/stimulation devices?

I’m a bit stuck and god forbid that the solution should be to reprogram my experiment in Psychtoolbox :crazy_face:

Thanks!

Cheers,
Gilles