pseudo-randomization in OSWeb and setting the underscores of the associated character in SPR

Comments

• sebastiaan

  April 2021

  Hi @deandgei ,

  Loop constraints are not supported in OSWeb, as you probably noticed. So you need to write a script that applies these constraints for you. The general logic is always the same:

  • Create a list (or array in JavaScript) of conditions
  • Shuffle the conditions until the constraints (which depend on the experiment) are met
  • Then use one element from the conditions on each trial

  In your case, the constraint boils down to checking whether there are two consecutive conditions that are identical and that are not 'F'. The script below shows how you can do that. This would go in the prepare phase of an inline_javascript at the start of the experiment.

  /**
   * Shuffles the order of elements in an array.
   **/
  
  function shuffle(array) {
      let counter = array.length
      while (counter > 0) {
          let index = Math.floor(Math.random() * counter)
          counter--
          let temp = array[counter]
          array[counter] = array[index]
          array[index] = temp
      }
      return array
  }
  
  
  /**
   * Checks whether the conditions array conditions two identical and consecutive
   * elements that are not 'F'.
   **/
  
  function needsShuffle(conditions) {
      for (let i = 0; i++; i < conditions.length - 1) {
          if ((conditions[i] !== 'F') && (conditions[i] === conditions[i + 1])) {
              return true
          }
      }
      return false
  }
  
  
  // Shuffle the array of conditions until it doesn't need shuffling anymore
  let conditions = shuffle(['C1', 'C2', 'F', 'C1', 'C2', 'F'])
  while (needsShuffle(conditions)) {
      conditions = shuffle(conditions)
  }
  
  // Assign as experimental variable so we can use it in other scripts
  vars.conditions = conditions
  

  Then, at the start of each trial, again in the prepare phase of an inline_javascript , you simply get the last element from the array and assign it to the condition variable, which you can then use in the normal way.

  // Pop the last element from the conditions array
  vars.condition = vars.conditions.pop()
  

  Does that make sense?

  Regarding the length of the characters: Chinese characters are essentially a monospace font where each character sits in a box of a fixed size. Latin characters are not, and even a monospace Latin font will not be matched in size to Chinese characters. The most pragmatic way to work around this is to use one of the Chinese punctuation characters instead of an underscore, because these are matched in length to the Character boxes. For example, below you can see that the Chinese full stop actually matches the widths of the characters:

  

  Hope this helps!

  — Sebastiaan

  
  
  Check out SigmundAI.eu for our OpenSesame AI assistant!
  
• deandgei

  May 2021

  Hi @sebastiaan,

  thank you very much for your detailed reply.

  I have copied your code in the prepare phase of an inline_javascript at the start of the experiment and also added vars.condition = vars.conditions.pop() at the start of each trial in the prepare phase of an inline_javascript

  1. I have changed the for loop in the needsShuffle(conditions) a little, now it looks like this: for (let i = 0; i <= conditions.length - 1;i++)
  2. This is my let conditions
  

  
  

  After I saved everything, two critical items belong to the same type would still show continuously. I tried to solve this problem these three days, but I can still not figure it out. I am sorry if it is too basic. Could you please help me solve this problem? 

  This is where I fill my stimulus. In the column "condition", the condition in row 1-10 is "F", row 11 -17 is condition "C1", row 18-25 is condition "C2".

  

  

  Besides, using one of the Chinese punctuation characters instead of an underscore solves the problem with the display.

  Thank you very much for your help! I am looking forward to your advice.

  Lili
• sebastiaan

  May 2021

  Hi @deandgei ,

  These scripts replace the condition column in the block loop (so this column should be removed from new_loop), and the second script should be at the start of each trial, so at the start of trial_sequence_1.

  Looking at your loop table, your situation is a bit more complex than I initially thought though, because you have a lot of other variables that, I assume, should be kept together with the condition variable. Is that right?

  What you could do is define a slightly more complex array of conditions, where each condition is itself an object with multiple variables (instead of only the name of the condition). For two trials and two variables (condition and ID ) this would look like this:

  let conditions = [
      {'condition': 'C1', 'ID': 1},
      {'condition': 'F', 'ID': 2}
  ]
  

  This would also require a few tweaks to the other scripts. Specifically, you'd have to change needsShuffle() so that it compares the condition variable only. And you'd need to change the script at the start of the trial so that each variable is assigned to an experimental variable (i.e. as a property of the vars object). I'll leave that to you to play around with though!

  — Sebastiaan

  
  
  Check out SigmundAI.eu for our OpenSesame AI assistant!