Millisecond Forums

There certainly isn't any simple code that would enable this. Beyond that, your description of the manipulation is too unspecific to suggest anything concrete or evaluate if this is possible at all.

"Black screen interruptions" intuitively seem more realistic to accomplish, but you will have to flesh this out first. I.e., how often or under which conditions should such interruptions occur? How long should they last? What -- if anything -- do you want to measure regarding the interruptions? etc.

Thanks for the reply Dave.
There is nothing we need to measure in the interruptions, they are merely a manipulation that i meant to create frustration and a feeling of lack of control in the participant. We are using other instruments to measure them later to observe the effects of this manipulation.
As for the "black screen interruptions" - something in the order of 30ms long black screens, spaced 7 seconds apart, starting a minute from the beginning of the first trial and lasting indefinitely (until aborted by the experimenter). This would give us time to exit the room before the interruptions begin. Ideally the participant would still be able to proceed with the task while being pestered by the black screens.

Okay, thanks. I've attached a very rough draft to give you the basic idea (I've shortened the times a bit, so the manipulation is more readily apparent for testing purposes). You'll want to look at the additional <trial outage> element as well as the new /branch in <trial move> that invokes the outage.

P.S.: This would annoy the hell out of me if I were a participant, but I guess that's the point... ;-)

Great! This will definitely have the desired effect :).
Thanks for your help, I'll keep you posted about our results..