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202 lines
8.3 KiB
JavaScript
Executable File
202 lines
8.3 KiB
JavaScript
Executable File
/* jspsych-xab.js
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* Josh de Leeuw
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*
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* This plugin runs a single XAB trial, where X is an image presented in isolation, and A and B are choices, with A or B being equal to X.
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* The subject's goal is to identify whether A or B is identical to X.
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*
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* documentation: https://github.com/jodeleeuw/jsPsych/wiki/jspsych-xab
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*
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*/
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(function($) {
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jsPsych.xab = (function() {
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var plugin = {};
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plugin.create = function(params) {
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params = jsPsych.pluginAPI.enforceArray(params, ['data']);
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// the number of trials is determined by how many entries the params.stimuli array has
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var trials = new Array(params.stimuli.length);
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for (var i = 0; i < trials.length; i++) {
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trials[i] = {};
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trials[i].type = "xab";
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trials[i].x_path = params.stimuli[i][0];
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// if there is only a pair of stimuli, then the first is the target and is shown twice.
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// if there is a triplet, then the first is X, the second is the target, and the third is foil (useful for non-exact-match XAB).
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if (params.stimuli[i].length == 2) {
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trials[i].a_path = params.stimuli[i][0];
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trials[i].b_path = params.stimuli[i][1];
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}
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else {
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trials[i].a_path = params.stimuli[i][1];
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trials[i].b_path = params.stimuli[i][2];
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}
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trials[i].left_key = params.left_key || 81; // defaults to 'q'
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trials[i].right_key = params.right_key || 80; // defaults to 'p'
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// timing parameters
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trials[i].timing_x = params.timing_x || 1000; // defaults to 1000msec.
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trials[i].timing_xab_gap = params.timing_xab_gap || 1000; // defaults to 1000msec.
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trials[i].timing_ab = params.timing_ab || -1; // defaults to -1, meaning infinite time on AB. If a positive number is used, then AB will only be displayed for that length.
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trials[i].timing_post_trial = (typeof params.timing_post_trial === 'undefined') ? 1000 : params.timing_post_trial; // defaults to 1000msec.
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// optional parameters
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trials[i].is_html = (typeof params.is_html === 'undefined') ? false : params.is_html;
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trials[i].prompt = (typeof params.prompt === 'undefined') ? "" : params.prompt;
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trials[i].data = (typeof params.data === 'undefined') ? {} : params.data[i];
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}
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return trials;
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};
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var xab_trial_complete = false;
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plugin.trial = function(display_element, block, trial, part) {
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// if any trial variables are functions
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// this evaluates the function and replaces
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// it with the output of the function
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trial = jsPsych.pluginAPI.normalizeTrialVariables(trial);
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switch (part) {
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// the first part of the trial is to show the X stimulus.
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case 1:
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// reset this variable to false
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xab_trial_complete = false;
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// how we display the content depends on whether the content is
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// HTML code or an image path.
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if (!trial.is_html) {
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display_element.append($('<img>', {
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src: trial.x_path,
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"class": 'jspsych-xab-stimulus'
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}));
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}
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else {
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display_element.append($('<div>', {
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"class": 'jspsych-xab-stimulus',
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html: trial.x_path
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}));
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}
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// start a timer of length trial.timing_x to move to the next part of the trial
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setTimeout(function() {
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plugin.trial(display_element, block, trial, part + 1);
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}, trial.timing_x);
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break;
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// the second part of the trial is the gap between X and AB.
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case 2:
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// remove the x stimulus
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$('.jspsych-xab-stimulus').remove();
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// start timer
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setTimeout(function() {
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plugin.trial(display_element, block, trial, part + 1);
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}, trial.timing_xab_gap);
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break;
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// the third part of the trial is to display A and B, and get the subject's response
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case 3:
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// randomize whether the target is on the left or the right
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var images = [trial.a_path, trial.b_path];
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var target_left = (Math.floor(Math.random() * 2) === 0); // 50% chance target is on left.
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if (!target_left) {
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images = [trial.b_path, trial.a_path];
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}
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// show the options
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if (!trial.is_html) {
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display_element.append($('<img>', {
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"src": images[0],
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"class": 'jspsych-xab-stimulus left'
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}));
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display_element.append($('<img>', {
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"src": images[1],
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"class": 'jspsych-xab-stimulus right'
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}));
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}
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else {
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display_element.append($('<div>', {
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"class": 'jspsych-xab-stimulus left',
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html: images[0]
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}));
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display_element.append($('<div>', {
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"class": 'jspsych-xab-stimulus right',
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html: images[1]
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}));
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}
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if (trial.prompt !== "") {
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display_element.append(trial.prompt);
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}
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// if timing_ab is > 0, then we hide the stimuli after timing_ab milliseconds
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if (trial.timing_ab > 0) {
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setTimeout(function() {
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if (!xab_trial_complete) {
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$('.jspsych-xab-stimulus').css('visibility', 'hidden');
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}
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}, trial.timing_ab);
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}
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// create the function that triggers when a key is pressed.
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var after_response = function(info) {
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var correct = false; // true when the correct response is chosen
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if (info.key == trial.left_key) // 'q' key by default
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{
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if (target_left) {
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correct = true;
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}
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}
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else if (info.key == trial.right_key) // 'p' key by default
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{
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if (!target_left) {
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correct = true;
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}
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}
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// create object to store data from trial
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var trial_data = {
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"trial_type": "xab",
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"trial_index": block.trial_idx,
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"rt": info.rt,
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"correct": correct,
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"stimulus_x": trial.x_path,
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"stimulus_a": trial.a_path,
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"stimulus_b": trial.b_path,
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"key_press": info.key
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};
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block.writeData($.extend({}, trial_data, trial.data));
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display_element.html(''); // remove all
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xab_trial_complete = true;
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// move on to the next trial after timing_post_trial milliseconds
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if(trial.timing_post_trial > 0) {
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setTimeout(function() {
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block.next();
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}, trial.timing_post_trial);
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} else {
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block.next();
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}
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};
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jsPsych.pluginAPI.getKeyboardResponse(after_response, [trial.left_key, trial.right_key], 'date', false);
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break;
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}
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};
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return plugin;
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})();
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})(jQuery);
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