> Could this be a problem with cumulative information build-up?
Yes. What you describe very much sounds like memory build-up in the Mac's media subsystem until the system starts to run out of resources. Things you can try:
- Different video format, e.g. MP4. MOV isn't necessarily the most efficient format these days.
- Cutting down the number of trials. It seems there are currently 7 repetitions of each video in a given block. Perhaps 5 or 6 repetitions would be sufficient, too? If the data files in your web account are a vaild indication of when the lagging starts, it most commonly seems to occur in the 5th block (not the 6th), after a total of around 190-200 trials have been completed.
- You can also try introducing a /posttrialpause to give Inquisit some specified time after a trial to free up memory. I'm not convinced this will help in this particular case because I suspect the memory build-up to occur in an OS component, not Inquisit directly, but it's worth a try nonetheless.
- Lastly, you could split the script into several separate ones (e.g. one per block) and then run those in random order via <batch>. That might
prevent the build-up from reaching critical mass.
/ file = "practice.iqx"
/ file = "mlothi.iqx"
/ file = "mhithi.iqx"
/ file = "mhitlo.iqx"
/ file = "mlotlo.iqx"
/ selectionmode = random