Pseudorandom trial structure /Importing CSV trial structure?

Comments

• sebastiaan

  October 2020 edited October 2020

  Hi @henrietel ,

  It depends on the kind of pseudorandomization that you need. If you have complex constraints, then your solution of copy-pasting very long loop tables would work, although it's clearly clunky. For simpler cases, you could use an inline_javascript item.

  For example, the following script would create an array of conditions ('a' and 'b') with a maximum repetition of 1, so at most twice the same condition in a row. You could put something like this at the start of the experiment:

  function shuffle(array) {
      array = array.slice()
      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
  }
  
  function max_rep(array) {
      let max_rep = 0
      let n_rep = 0
      for (let i = 0; i < array.length; i++) {
          if (i === 0) {
              continue
          }
          if (array[i] === array[i - 1]) {
              n_rep++
              if (n_rep > max_rep) {
                  max_rep = n_rep
              }
          } else {
              n_rep = 0
          }
      }
      console.log(max_rep)
      return max_rep
  }
  
  vars.conditions = ['a', 'a', 'a', 'a', 'b', 'b', 'b', 'b']
  while (true) {
      vars.conditions = shuffle(vars.conditions)
      if (max_rep(vars.conditions) <= 1) {
          break
      }
  }
  console.log(vars.conditions)
  

  And then in each trial, you would get one of the conditions from this array and assign it to the condition variable:

  vars.condition = vars.conditions.pop()
  

  This may not be what you need exactly, but that's the general type of solution to this kind of issue.

  Cheers!

  Sebastiaan

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

  October 2020

  Hi henriete,

  What do you mean with Opensesame doesn't support pseudorandomization? Do you mean a specific type of randomization or just shuffling the trials? Because in the loop table, you can set the *order* field to random, which does randomization.

  Does that help, or am I misunderstanding?

  Eduard