pseudorandomization with just one cycle
I have an experimental setup in which I show 5 images.Two of them are fillers and need to always appear in position 2 and position 5 (however it is random which of the two appears in position 2 and which in 5). The other 3 images have to appear in random order in positions 1, 3 and 4.
Is there a way to do this? I read about the constraint option but I do not think it applies in this case as I only have one cycle.