Redefining stimuli after each timeline block

[vargamartonaron]

Hey!

I am trying to put together a test and would like to redefine the stimuli after each fixation-test-feedback timeline ends. Simply I defined a function stimuli_reroll wich takes an array test_stimuli and fills it up with according random stimulus. I want this function to execute before every timeline repetition to get blocks of randomized stimuli via the function. I have tried this with the jsPsychCallFunction plugin. I have tried the on_timeline_start property in the timeline node too with no success. I think the problem lies somewhere as i try to call the stimulus with the jspsych.timelinevariable function. My error is so "cannot read "stimulus" (undefined).If i fill up test_stimuli array only once and not trying to execute the function blockwise, the experiment runs smoothly. Any advice or help is greatly appriciated! See the code below.

//------This script generates a random order of stimuli with the rules of the predefined methods-----
stimulus_set = []

var relay = 0

const fp_con_list = [
    ["FFFFF", "no_conflict", "1"],
    ["PPPPP", "no_conflict", "9"]
]
const fp_inc_list = [
    ["FPPPF", "low_conflict", "9"],
    ["PFFFP", "low_conflict", "1"],
    ["FFPFF", "high_conflict", "9"],
    ["PPFPP", "high_conflict", "1"]
]
const hn_con_list = [
    ["HHHHH", "no_conflict", "2"],
    ["NNNNN", "no_conflict", "8"]
]
const hn_inc_list = [
    ["HNNNH", "low_conflict", "8"],
    ["NHHHN", "low_conflict", "2"],
    ["HHNHH", "high_conflict", "8"],
    ["NNHNN", "high_conflict", "2"]
]

const fp_group = [fp_con_list, fp_inc_list]
const hn_group = [hn_con_list, hn_inc_list]

function stimulus_finder(group) {
    congruency = Math.floor(Math.random() * group.length) //randomly choosing from congruent or incongruent stimuli (50-50%)
    stimulus = Math.floor(Math.random() * group.length) // randomly choosing a stimulus from the list (25% low conflict, 25% high conflict, 50% no conflict)
    stimulus_set.push(group[congruency][stimulus])
}

function group_relay() { // kindergarden way to switch between fp and hn groups

    if (relay === 0) {

        stimulus_finder(fp_group)

        relay = 1
    } else {
        stimulus_finder(hn_group)

        relay = 0
    }

}

function set_factory(total) {
    for (var i = 0; i <= total; i += 1) {
        group_relay()
    }
}

var jsPsych = initJsPsych({
      on_finish: function () {
        jsPsych.data.displayData();
      },
      override_safe_mode : true
    })
var test_stimuli = []

function stimuli_reroll(){
  stimulus_set = []
  test_stimuli = []
  set_factory(1)
for (i = 0; i < stimulus_set.length; i+=1) { //unwrapping nested array to access wanted stimuli (strc of stimulus_set: [(Array(3)), (Array(3)), etc...], strc of new array: {stimulus: 'NNNNN', congruency: 'no_conflict', correct_response: '8'}
  test_stimuli.push({stimulus : stimulus_set[i][0], congruency : stimulus_set[i][1], correct_response : stimulus_set[i][2]})
}

}
    var timeline = []

    var test = {
      type: jsPsychHtmlKeyboardResponse,
      stimulus:jsPsych.timelineVariable("stimulus"),
      choices: ["1","2","8","9"],
      trial_duration: 1500,
      response_ends_trial: false,
      data: {
        task: "response",
        correct_response: jsPsych.timelineVariable("correct_response"),
        congruency: jsPsych.timelineVariable("congruency")
    

      },
      on_finish: function (data) {
        data.correct = jsPsych.pluginAPI.compareKeys(data.response, data.correct_response);
      }, 
  }

var fixation = {
    type: jsPsychHtmlKeyboardResponse,
    stimulus: '<div style="font-size:60px; color: gray;">+</div>',
    choices: "NO_KEYS",
    trial_duration: 500,
    response_ends_trial: false,
    data: {
      task: 'fixation'
    },
    save_trial_parameters: {
      stimulus: false
    }
  }

  var feedback = {
  type: jsPsychHtmlKeyboardResponse,
  stimulus: function(){
    var last_trial_correct = jsPsych.data.get().last(1).values()[0].correct;
    if(last_trial_correct){
      return "<p></p>"; 
    } else {
      return "<p>Incorrect / No response detected</p>";
    }
  },
  trial_duration: 800,
  response_ends_trial: false,
}



    var test_procedure = {
      timeline: [fixation, test, feedback],
      timeline_variables: test_stimuli,
      repetitions: 6,
      on_timeline_start: function() {
            return stimuli_reroll
            }

     
        }
  

 
    

    timeline.push(test_procedure)

    jsPsych.run(timeline)

[becky-gilbert]

Hi @vargamartonaron, sorry for the slow response!

I could be wrong, and hopefully @jodeleeuw will correct me if so, but I'm pretty sure the timeline_variables array can't be modified dynamically after the experiment has started. Have you looked at whether you could use a custom sampling function to achieve what you're after here? The custom sampling function receives an argument t which is "an array of integers from 0 to n-1, where n is the number of trials in the timeline_variables array", and the function should return an array of indices that specifies the order of the trials. So maybe you could stick all of your stimulus information into a single array, pass that to timeline_variables, put your logic for selecting trials into the custom sampling function, and return subsets of the trials you want on each pass through the timeline. You could probably get the indices for the trials you need by filtering the array.

If that doesn't work, then instead of using timeline_variables, I would replace the references to timeline variables in your trial objects with dynamic parameters that reference test_stimuli, and use a loop node to repeat your test procedure timeline. In the loop function, I would add the logic for whether or not the loop should continue, whether the test_stimuli index should change, and for modifying the test_stimuli array when necessary. So it would look something like this:

var trial_index = 0;
var test_stimuli = []

// initialize the test_stimuli array ...

var test = {
    type: jsPsychHtmlKeyboardResponse,
    stimulus: function() {
      return test_stimuli[trial_index]]
    },
    // more parameters...
}

// more trial objects

var loop = {
  timeline: [fixation, test, feedback],
  loop_function: function(data) {
    trial_index++;
    // check if we've reached the last trial in test_stimuli
    if (trial_index == test_stimuli.length) {
      // logic here to modify the test_stimuli array or stop the loop 
    } else {
      return true; 
    }
  }
}
timeline.push(loop)

Does that help at all? Let us know if you want further guidance with implementing either of these approaches.

[vargamartonaron]

Thank you for the helpful reply! I think I am going to stick with the second option. I am going to post further questions if I would run into something I can't solve.

Best wishes,
Marton

[vargamartonaron]

Dear Becky!

For some reason, your code executes with the following error message:

Trial level node is missing the "type" parameter. The parameters for the node are: {}

Even for a stimuli array as simple as [1,2,3,4,5]

Any clue what might be the problem? Perhaps the error lies within the stimulus definiton.

Best wishes,
Marton