Stimulus randomization

What I would do is:

  1. Set up a list of cue images and shuffle it.
  2. When the fractals column is, say, fractals/cue.png override it by setting the value as cue_images[fractals_and_targets_loop_1.thisN]

Does it matter that you could randomly get two cues very close together? If yes, then have a look at how I preload PM cues in my prospective memory demos.