Hi Greg,
In that particular script, I am using a feature of PsychoPy that allows you to give it measurements in centimeters rather than in pixels. In order to do that, you need to go into the monitor center (the icon at the top with two monitors) and create monitor profile that contains information about the physical size and the resolution of of your monitor. I call my configuration "Default", so you'll either have to call yours "Default" as well, or you'll have to change the code in the script to reflect whatever you call yours.
Otherwise, you can replace the code under the #Setup Screens comment with this:
window = visual.Window(fullscr=True)
#Create the image object. Tell it to use our window object.
CenterImage = visual.ImageStim(window)
LeftImage = visual.ImageStim(window)
LeftImage.setPos((-600,0))
RightImage = visual.ImageStim(window)
RightImage.setPos((600,0))
You'll need to play around with the values sent to the setPos function to get it to fit on your screen where you want it. I really recommend just setting up your monitor in the monitor center though. It makes it really easy to move the experiment to another computer and know that your measurements are accurate.
-Jared
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Jared Roberts
US2003071783