How can be done trials in a task in diffrent proportion ?

Comments

• eduard

  January 2018

  Hi,

  Add an inline_script before your loop and put this code in there (prepare phase):

  
  import random
  
  no_trials  = 20 
  ratio_rep = 0.6 # how many repetition trials are in a block
  # make sure that the ratio can be reproduced with the number of trials
  var.trials = [0]*0.6*20 + [1]*(1-0.6)*20
  random.shuffle(var.trials)
  

  Now the variable var.trials will have 0s for all the repetitions and 1s for all switches. In your experiment you just have to access every item in that list one after another, so that you get the correct type per trial.

  Does that help?

  Eduard

  
• bruksist

  January 2018 edited January 2018

  Thank you very much for the response
  But unfortunately, when I tried your solution, I got the "can't multiply sequence by non-int of type 'float'" error for the "var.trials = [0] * 0.6 * 20 + [1] * (1-0.6) * 20" line. I searched about this but ı couldn't understand the solutions suggested because the examples are not similar to mine and they are very complicated for me.
• bruksist

  January 2018
• eduard

  January 2018

  Hi,

  my bad, replace var.trials = [0] * 0.6 * 20 + [1] * (1-0.6) * 20 with var.trials = [0] * int(0.6 * 20) + [1] * int((1-0.6) * 20)

  Does that work?

  
• bruksist

  January 2018

  Hi,
  it works but I am sorry that I couldn't understand how it show switch ( changed response e.g. b to n) and non-switch (unchanged response e.g. b and again b) trials?
  
  I tried to analyze the logic from the quickrun file, but I couldn't get it. Could you please help? Thank you
• eduard

  January 2018

  var.trials will contain 0s and 1s in a certain proportion. When you present your stimuli, you have to do it contingent on the number in the list. If var.trials[current_trial_number] == 0 present a repeated stimulus, else, present a switched stimulus. The exact way to implement this. depends on your stimuli and your preference, there are multiple options.

  Does that make sense?

  
• bruksist

  January 2018

  I am sorry it is a bit much for novices, but I am studying on hard. I believe I will achieve Until that time I will enter stimuli manually and present sequentially. Thank you very much