Collect RT but wait to display next stimulus

I am trying to set up an experiment that will be used to collect data with fMRI. I have about 20 movies (1-3 seconds long). After each movie plays, I want to record the subject's response and response time (either a 1 or a 4 on keyboard). I also want to wait a certain interval *despite receiving a response* before the next movie plays. There are five different interval times, each matched to a specific movie. I can figure out how to wait before displaying the next movie, OR how to record the response & RT, but I can't figure out how to accomplish both.

If the interval varies by which movie preceeds it, the easiest way would simply be to add a blank text (~) stimulus immediately following each clip--using whatever time value is appropriate. If you have any trouble with it, send me a copy of your input file and I'll take a look at it.

Blair