Question about mworks update

Hi Chris,

You write that in version 12

“Fixation point stimuli (both rectangular and circular) now report active fixation only when on screen”

What exactly does that mean?
When I dequeue a fixation stimulus + update the display, fixation is not longer required – even if I have a eye_in_window condition? Or is reported as not fixating regardless of eye position?

Sorry this may be trivial but I am confused :-/

Hi Alina,

As of MWorks 0.12, when you dequeue a fixation point stimulus and update the display,

  1. the variable assigned to trigger_flag is set to false, and
  2. subsequent changes to the variables assigned to trigger_watch_x and trigger_watch_y are ignored, meaning that trigger_flag stays false regardless of eye position.

Re-queueing the fixation point and updating the display will reactivate fixation monitoring. I’m pretty sure this is how fixation points were always supposed to work. (If the fixation point isn’t on screen, it doesn’t make much sense to ask if the subject is looking at it.)

If your experiment relies on fixation monitoring via offscreen fixation points, the good news is that MWorks 0.12 won’t give you any false fixations. The bad news is that you’ll have to change your experiment so that the fixation point is always on screen, and set its alpha_multiplier to zero when you want it hidden. This will also require that you live queue the fixation point, so that changes to alpha_multiplier will be visible after you update the display and not require that the fixation point be dequeued and re-queued first.


Thanks. Yes unfortunately for me it means I have to recode a running experiment.