This Question is directed towards those with experience involving PsychoPy tasks implemented in the scanner:
We want to provide the monitor center with our screen parameters, but the task is projected form a laptop onto a screen, which the subject then sees through a mirror.
My Question is which parameters have others used in this scenario?
These, for example, are the projector settings we have:
screen resolution should be set at 1920 x 1080
The width of the projector is 29 inches.
The distance they are viewing is roughly 45 inches.
The mirror distance is much closer.
and the subject doesn’t see the laptop.
Thanks for your help.
Hi Kevin, if you are not confident of the optics and geometry here, it might be best to stick to units like
pixels. The geometry is only important if you are specifying stimulus dimensions in terms physical units like
My intuitive grasp of the optics would be that the effective eye-screen distance here is 45 inches plus the eye:mirror distance (I’m assuming here that by “viewing distance” you mean the distance from the projection screen to the mirror). i.e. the apparent distance is the virtual distance “behind” the mirror of the viewed object plus the distance from the viewer to the mirror surface itself. Of course there might be session-to-session variability of that distance depending on subject positioning and also some variability in the eye:mirro distance, which itself will be hard to measure. But they should be relatively small influences compared to the overall distance, so perhaps you can get away with a constant value of, say 47 inches across sessions.
(Feeling mildly weird using imperial measurements rather than actual sciencey units… hope you don’t introduce errors when converting to cubits or fathoms.)