feedback problem

[mary-9555]

Hi there.
Can someone please tell me what is wrong with this coding? or what is missing in it? I would really appreciate it.

var image_trial = {
  type: 'image-button-response',
  stimulus: 'img/b/004_o_m_s_b.jpeg',
  choices: ['sad', 'frightened', 'neutral','angry','disgusting','happy'],
  data: {
    stimulus_type: 'image'
  },
  on_finish: function(data){
    if(jsPsych.pluginAPI.compareKeys(data.response, "sad")){
      data.correct = true;
    } else {
      data.correct = false; 
    }
  }
}

var feedback = {
  type: 'instructions',
  stimulus: function(){
    var last_trial_correct = jsPsych.data.get().last(1).values()[0].correct;
    if(last_trial_correct){
      return "<p>Correct!</p>"; 
    } else {
      return "<p>Wrong!... The correct answer was 'sad'.</p>";
      show_clickable_nav; true,
    button_label_previous; 'previous',
    button_label_next; '<h2>next</h2>'
    }
  }
}

timeline.push(image_trial, feedback);

[becky-gilbert]

Hi @mary-9555, can you say more about what's happening when you run the code? Are you seeing any errors in the browser's JavaScript console?

I did notice a few things:

1. The jsPsych.pluginAPI.compareKeys function is just meant for comparing keyboard responses, not button responses. So in your image_trial, you should compare the participant's response and correct response directly in the on_finish function. The participant's button response is stored using the indices in the choices array, and in your case "sad" is the first button choice (index = 0), so you want to check if the response was "sad" like this: if (data.response == 0) { ...
2. In your feedback trial, using the instructions plugin might not be ideal here, because that plugin is meant for displaying several pages that the participant can go forward/backwards through. If you just need to display a single page with the "correct" or "incorrect" feedback, then you might want to use one of the html-* plugins. If you want the participant to have to click a button to continue on from the feedback page, you can do that using the html-button-response plugin.

Also, if you do want to stick with the instructions plugin for your feedback trial, there are some problems with the way this trial is defined:

3. Instead of a stimulus parameter, the instructions plugin has a pages parameter that must be an array of one or more strings (the HTML-formatted content for each page). See the instructions plugin documentation for more info.
4. You have a misplaced curly bracket in this trial. You should end the if/else statement and stimulus function with two curly brackets after the last return statement, and the remaining 3 trial parameters should be on the same level as type and pages.
5. The trial parameters and values should be separated by a colon (:) rather than a semi-colon (;).

var feedback = {
  type: 'instructions',
  pages: function(){
    var last_trial_correct = jsPsych.data.get().last(1).values()[0].correct;
    if(last_trial_correct){
      return ["<p>Correct!</p>"]; 
    } else {
      return ["<p>Wrong!... The correct answer was 'sad'.</p>"];
    }
  },
  show_clickable_nav: true,
  button_label_previous: 'previous',
  button_label_next: '<h2>next</h2>'
}

[mary-9555]

Thanks for your reply Becky.
You are right, this is the problem: The jsPsych.pluginAPI.compareKeys function is just meant for comparing keyboard responses, not button responses!

I followed this recommendation: in your image_trial, you should compare the participant's response and correct response directly in the on_finish function: if (data.response == "sad") { ...

But it didn't work !!
There was a wrong! feedback for every answer! (even when you choose the correct button!).
I wish there was a jsPsych.pluginAPI.comparebuttons function for this kinda task...

[becky-gilbert]

Hi @mary-9555, oh sorry, I just remembered that the button responses are stored as numbers in the trial data, where 0 refers to the first button option in choices, 1 is the second button, etc. So my response above is wrong - I'll edit it so that anyone else reading this doesn't get confused.

The "sad" button is first in your choices array (i.e. index 0), so in the on_finish function for your image_trial, you want to check whether data.response is 0, like this:

on_finish: function(data) {
  if (data.response == 0) {  // 0 is 'sad', 1 is 'frightened', 2 is 'neutral', etc.
    data.correct = true;
  } else {
    data.correct = false; 
  }
}

BTW the data that's produced by the image-button-response plugin is explained in the plugin documentation. And if you're ever unsure of what the trial data looks like, you can print it to the browser's JavaScript console in the trial's on_finish function like this:

on_finish: function(data) {
  console.log(data);
  ...
}

I hope this helps!

[mary-9555]

It worked ! :))
Thanks a million Becky !