Hi,
I want to have an experiment in which a yellow rectangle appear constantly in the middle of a black screen, and some little stimulus are showing inside the rectangle at 4 different locations at a randomize order. Every time that a little stimuli appears, its counts as a trial and write the subject response.
Can I somehow define a permanent background of a big yellow rectangle inside the all black screen? I tried to make 4 stimulus of the rectangle with the little stimuli at 4 different locations. The problem is that the rectangle is disappearing when moving from trial to trial and I need it to stay. Is there a way to do this?

Thank you,
Roy