Maintain fixation point throughout task? (case 20948)

[emartin8]

Hi.
I would like to maintain a fixation point on the screen throughout my task and have images displayed over the fixation point periodically. That is, I don't want there to ever been a blank screen but always either a fixation point or an image. Also, I need the time in which the fixation is displayed before showing the image to be "jittered" (either 1500, 2000, or 2500 ms).

I have tried a few things including creating two row per trial-the first row for a fixation with a jittered duration and then the next row having both a display of the fixation cross (with a time of "0") and an image (with a loc of "0,0,0") but there is a gap on the screen between the display of the first row and the second row.

Any help would be greatly appreciated. I saw a similar thread created in 2007 but there was no response to the question.

Thank you!
Liz