[solved] Presenting stimuli at different frequencies

Comments

• sebastiaan

  December 2011 edited 10:06PM

  Hi Rob,

  There is. As you say, for a low number of stimuli, it's probably better to manually create a list, but ...

  Method 1

  ... for a large nr of stimuli you could draw a number from a gaussian distribution. You could do this by inserting an inline_script at the start of the trial, with (something like) the following code in the prepare phase.

  import random
  nr = round(random.gauss(5, 1)) # Mean = 5, Stdev = 1
  self.experiment.set('my_random_number', nr)

  See http://docs.python.org/library/random.html#random.gauss

  Method 2

  This has the disadvantage that you cannot control exactly how often each number occurs (although for a large number of trials this probably doesn't matter). If you want exact control, you could add an inline_script to the start of the experiment, with (something like) the following code in the run phase:

  import random
  self.experiment.nr_list = []
  self.experiment.nr_list += [1]*5
  self.experiment.nr_list += [2]*10
  self.experiment.nr_list += [3]*5
  random.shuffle(self.experiment.nr_list)

  This generates a randomly ordered list of numbers, where '1' occurs 5 times, '2' occurs 10 times, etc. To draw a number from this list on every trial, add an inline_script at the start of the trial, with (something like) the following code in the prepare phase:

  nr = self.experiment.nr_list.pop()
  self.experiment.set('my_random_number', nr)

  Hope this helps!

  Sebastiaan

  
  
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• robtaylor

  December 2011 edited 10:06PM

  Hi Sebastiaan
  Sorry for my delayed reply, and thank you for your help. That helps greatly!
  Great support!
  Cheers,
  Rob