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Split screen lexical decision task


I’m using the PsychoPy3 version for Windows and I’m working on a split screen lexical decision task with priming: half of my target words should be randomly presented to the left visual field and the other half to the right visual field. To do this I tried to adjust the position [x,y] settings in my target text stimuli in the Builder (see the screenshot), but the problem is that these settings set the same position for all the stimuli and I have no idea how to randomize it (left vs. right).
Maybe I should code to do it?

Thank you in advance!

You’ve applied a constant value (0.3, 0.3) to the position, so yes, that position will be constant. There are several ways to provide a random but balanced position. Probably the easiest way for you would be to specify all the possible values you want within the conditions file linked to the loop which controls your file, and specify that the loop should run in a random order.

Thank you, Michael!
If I understood it correctly, I should add a column with coordinates to my condition file, like this?

But the problem is that when I try to refer to this column in settings, it gives an error…

  • Can you provide the actual error message?
  • The view is obscured, so it’s hard to tell if there is an actual loop defined that links to this conditions file?
  • That variable may be being interpreted as literal text rather than a Python expression, so you might need to use something like this rather than just coordinates:

to evaluate the expression. Or in the conditions file, split the x and y values into their own columns (this will probably simplify things for you at the analysis stage), and then use an expression like this:

(x_coord, y_coord)

It works! Thanks a lot! I just added eval.

But now I have another question: I’m going to replicate one study, and there the targets are presented such that ‘the center of each word was 3.0° and the innermost edge of each word was 2.0° from the center of the monitor’ (they used the Super-Lab-Pro 2.0. Do you know how to apply the same value (it’s equivalent) to the position in PsychoPy?

If you set the units of the stimulus to be in degrees, then just provide a value of 3.0 for its coordinates and it will be centred 3.0 degrees from the centre of the monitor, if you have entered the geometry of the monitor correctly.

We can’t easily specify the inner boundary of the word, as that will vary with word length. You’d need to figure out some way of manipulating the font size to compensate for the word length.