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                    // This file demonstrates how to present images in a randomized order.
    // The image will be presented one by one at a time.

    const jsPsych = initJsPsych({
        on_finish: function() {
    console.log(`jsPsych Version ${jsPsych.version()}`)

    const pixi_flag ='pixi_flag') === '1' ? true : false;

    const instruction = {
        type: jsPsychHtmlButtonResponse,
        stimulus: 'Click on the Start button.',
        choices: ['Start'],
        prompt: "This is a sample program for the jspsych-psychophysics plugin.",

    const images = [ // All the images used in this demo

    // Preloading files are needed to present the stimuli accurately.
    const preload = {
        type: jsPsychPreload,
        images: images,

    const trial = {
        timeline: [
                type: jsPsychPsychophysics,
                pixi: pixi_flag,
                stimuli: [
                        obj_type: 'cross', // fixation
                        line_length: 20, // pixels
                        line_width: 4
                        obj_type: 'image',
                        file: jsPsych.timelineVariable('fileName'),
                        show_start_time: 500 // ms after the start of the trial
                canvas_height: 500,
                prompt: 'Press any key to proceed.',
                data: {'file_name': jsPsych.timelineVariable('fileName')} // for identification
        timeline_variables: [
            {fileName: images[0]},
            {fileName: images[1]},
            {fileName: images[2]}
        randomize_order: true
    }[preload, instruction, trial])