Thanks. That is exactly what I was looking for. Using the setup above, is it possible to randomly select between a set of positions? For instance, if there are two images, one on the left and one on the right, I want to set up the experiment so that it randomly selects between position 1 (image 1 on the left and image 2 on the right) and position 2 (image 1 on the right and image 2 on the left). Furthermore, I want to make sure the randomization is balanced so that it selects position 1 or position 2 50% of the time. In my set of stimuli, there will only be this set that will need to be randomly positioned.