setting experiment variables

Comments

• vatsalthebest

  February 2018 edited February 2018

  Hey!

  Looks like you're using an older version of opensesame. As for opensesame 3.0 we use var. Function in opensesame 3 to create an experimental variable in python

  import random

  var.fixdurations = range(400, 1700, 100)

  var.fixduration1 = random.sample(var.fixduration, 1)

  If this doesn't work add another inline script at the very start of the
  experiment.

  And add this code:

  var.fixduration = []

  Alternatively you could add this variable into the loop that way you won't need any python scripting.

  Hope this helps

  Vatsal
• mariosav

  February 2018

  Thanks Vatsal. I'll give it a shot. But I think the problem is with the last step of setting the experiment, variable, ie., this part: exp.set('fix1dur', fix1duration)
  Up to that point, everything works well. That is, if I print fix1duration I correctly get one of the values from the list. But, I can't set these values to the sketchpad duration.
  Even if I delete all the code and just say exp.set('fix1dur', 200), I can't use [fix1dur] in the sketchpad duration field.
  marios
• eduard

  February 2018

  Hi Marios,

  Put the code in the prepare phase and you should be set

  Eduard

  
• mariosav

  February 2018

  You're right, it works! Thanks Eduard!
  m
• mariosav

  February 2018

  Eduard, I still can't get my head around this and why the code doesn't work in the Run phase. I can see a situation where putting the code in the Prepare phase wouldn't work for me. For example, let's say I have a mouse_response item and I want to set the duration of a sketchpad based on the response RT. I would use this code on an inline after the mouse_response item but before the sketchpad:
  ** fixduration = 5000 - exp.get('response_time')
  exp.set('fixdur', fixduration) **
  and then use [fixdur] in the duration of the sketchpad.
  Obviously I cannot prepare the inline as I don't have a value for 'response time' at the start. And it wouldn't work in the run phase either! My questions then are: 1) why doesn't it work in the Run phase 2) what do I do to make this work??
  Cheers,
  marios
• eduard

  February 2018

  Hi,

  Here a link to an explanation why this is. Basically, preparing things improves the timing of your stimuli.

  Sketchpads are always created in the prepare phase. That is, they are first called before all other items' run phases are called. So, if you need to present anything that depends on participants responses, you wouldn't use sketchpads, but feedback items. They are created in the run-phase of sequence, so that you can use responses to draw onto them.

  Hope this makes sense.

  Eduard

  
• mariosav

  February 2018

  Ok, I get it now! Thanks!!