[solved] Present stimuli for different durations in a random order

Comments

• lvanderlinden

  February 2016 edited 1:41PM

  Hello,

  One possibility is that you define at the beginning of every block a list with all possible durations:

  • Append an inline_script item to your block sequence, and place something like the following code in the Prepare tab:

  # Make a list with all possible duration values.
  # The list should be as long as you have trials in your block:
  
  # For example, if you want 5 different possible values for the variable
  # Duration, and every value should appear twice (i.e., every block
  # contains 10 trials):
  lDurations = [300,400,500,600,700] * 2
  
  # Shuffle the list:
  import random
  random.shuffle(lDurations)
  

  Next, pick one duration from this list at the beginning of every trial, without replacement.

  • Append an inline_script item to the beginning of your trial sequence, and place the following code in the Prepare tab:

  # Get duration on the current trial:
  var.duration = lDurations.pop()
  

  The above inline_script should be placed before the sketchpad item in which you want to use the duration. You can use the square-bracket method, that is [duration], as normally.

  Hope this helps!

  Cheers,

  Lotje

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• amihai_gottlieb

  February 2016 edited 1:41PM

  Dear Lotje,

  I have done what you wrote and it solved my problem!
  Thank you very very much.

  One comment - i needed to make sure to put the lDurations function before in a preparation part before the loop.

  Amihai