I’ve got a bunch of image files, and I want to present each image either on the left or the right (randomly, with the location recorded in the data file). Participants will respond to each stimulus by pressing one of two possible keys. How can I do this? Thanks.
Yes, you need to create a trial variable (click on Experiment menu then select Trial Variables). Create two levels, one for right and one for left. In the Level Selection tab of the Edit Trial Variable dialog (screen), make sure to set the “order” option to one of the two Random options.
The next and last step is to edit the picture event itself and edit its settings so that the position uses the trial variable that you just created.