I’m trying to program an experiment that will present movies (with audio) and, at specific times, present auditory probes (100 ms 1000 Hz tone). I am able to get something working; however, every time the probe is presented, the screen flickers for about a frame and an unwelcome visual event also occurs. I’m not sure if this has to do with my computer (it is an intel dual core 2.66 GHz) or how I’ve set up the experiment. The experiment is set up as multiple trials, rather than as events linked to a single trial. Blanks between sounds are empty text files that are set not to erase the screen. These events end on a time out. I’m not able to upload the experiment but I would greatly appreciate any advice to help get rid of the flicker and can easily provide more info about the experiment if you require more details.