How can I get out of the staircase loop in psychopy - adaptive oddball paradigm

Question

I try to programm a relative simple adaptive oddball task using the psychopy coder. As I am relatively new to python I don't know how to deal with the following situation and hope that you could help:

For the deviants within the oddball I wanna use the stair handler provided by psychopy. Everytime the deviant shows up it should adapt (e.g. in luminance) to the answer that was given before. My problem is that I don't know how to switch back to the standard stimuli after the deviant was presented. The stair handler seems to force the programm to stay in that loop until it is done. I can imagine that one simply needs to set a break within the for-loop but I don't know how. Does anyone have an advice on how to deal with this or could post a little example?

many thanks in advance, Johannes

Answer 1

I guess there are two options. One would be to use the stairhandler as the loop to define trials and then just use filler objects for presenting non-oddballs (standards). The following is essentially pseudo-code, in case that wasn't obvious!:

for thisLevel in stairs:
  continuePresenting=True
  while continuePresenting:
    if random()>oddBallFraction:
      presentOddball(thisLevel)
      continuePresenting = False #go to next entry in loop
    else:
      presentStandard()

The other alternative is that you have a loop for your presentations and then use the next() function of the staircase http://www.psychopy.org/api/data.html#psychopy.data.StairHandler.next

Jon