How should I sample at random from the list? I Have added as per your advice the following:
/ items = (1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0)
/ replace = false
/ flashing = 0
/ ontrialbegin = [
values.flashing = list.flashing.?
Also, what do you mean by inserting the shapes? Changing the color from white to red?