Repeating Multiple Stimuli Within a Trial

[SIZE=2]I'm trying to set up an experiment where the subjects are asked to choose which stimulus better represents a character attribute such as attractiveness. The way they chose the stimulus is to press either 1 for the first stimulus shown or 0 for the second stimulus shown. I would like to do this within a trial because I need to be able to randomize the order in which the subjects see the different pairs of pictures. Ideally, I would like to be able to set it up so that there are four stimuli shown(picture1, blank screen, picture 2, blank screen) for a set amount of time but at any time the subject may press 1 or 0 and move onto the next trial (set of picture pairs). I've tried a few different things and looked through the boards and haven't been able to find a solution and was hoping you could help. Thanks![/SIZE]