Timing on a reaction time task (case 11321)

[Nick00004]

Hello,

I'm using a Flanker task that times out at 450ms at which point, subjects receive an error message and move on to the next trial. What I would like, but can't seem to figure out, is to have the stimuli on the screen appear for 250ms and disappear afterwards to a blank screen (giving participants 200ms still to repsond: 450-250ms). Right now, it seems the stim have to remain on screen until the eventual time out.

Any help would be greatly appreciated.

Nick