Yes, I changed the background color to a blue - blue is always the background color. So, in between each frame, there is a quick flash where the screen is completely blue, and then it shows the next frame, where the background is blue again. This is a problem for 2 reasons:

1. I want participants to make several ratings of one photo, so for several frames I have the same photo, with just the rating scale changing. It is distracting that after each response, the photo flashes away and back. In the old version I used to use, if something was in the same place from frame to frame, it would just stay there.
2. At one point I want to show a black screen, and then the black screen with a fixation point. I can't have a flash of blue in between the two screens or the effect won't work.