video_keyboard_response errors for simple priming experiment #1693

Cluster-Bomb · 2021-03-30T02:36:18Z

Cluster-Bomb
Mar 30, 2021

Hi there - getting the following errors:

jspsych.js:2234 Invalid media_type parameter for jsPsych.pluginAPI.registerPreload. Please check the plugin file.
jsPsych.pluginAPI.module.registerPreload @ jspsych.js:2234
jspsych-pavlovia-2020.2.js:513 [pavlovia 2020.2] init | _configure.response= Object
jspsych-pavlovia-2020.2.js:513 [pavlovia 2020.2] init | _openSession.response= Object
jspsych-video-keyboard-response.js:137 Uncaught TypeError: jsPsych.pluginAPI.getVideoBuffer is not a function
at Object.jsPsych.plugins.video-keyboard-response.plugin.trial (jspsych-video-keyboard-response.js:137)
at doTrial (jspsych.js:795)
at nextTrial (jspsych.js:770)
at Object.window.jsPsych.core.finishTrial (jspsych.js:235)
at end_trial (jspsych-html-keyboard-response.js:101)
at jspsych-html-keyboard-response.js:142

Code is below:

<!doctype html>
<html lang="en">

<head>
	<title>Effect of Frame of Reference on Biological Motion [jsPsych]</title>
	<meta charset="UTF-8">

	<script type="text/javascript" src="jspsych-6.0.0/jspsych.js"></script>
	<link href="css/jspsych.css" rel="stylesheet" type="text/css" />

	<script type="text/javascript" src="plugins/jspsych-html-keyboard-response.js"></script>
    <script type="text/javascript" src="plugins/jspsych-image-keyboard-response.js"></script>
    <script type="text/javascript" src="plugins/jspsych-video-keyboard-response.js"></script>

	<script type="text/javascript" src="lib/vendors/jquery-2.2.0.min.js"></script>
	<script type="text/javascript" src="lib/jspsych-pavlovia-2020.2.js"></script>

</head>

<body>
	<script type='text/javascript'>

		/* create timeline */
		var timeline = [];


		/* init connection with pavlovia.org */
		var pavlovia_init = {
			type: "pavlovia",
			command: "init"
		};
		timeline.push(pavlovia_init);

		/* define welcome message trial */
		var welcome = {
			type: "html-keyboard-response",
			stimulus: "Welcome to the experiment. Press any key to begin."
		};
		timeline.push(welcome);

		/* define instructions trial */
		var instructions = {
			type: "html-keyboard-response",
		    stimulus: "<p>In this experiment, a silhouette of the ground " +
                "will appear on the top or bottom of the screen</p>" +
				"<p>This will be followed by a moving person animated as several moving " +
				"dots. This can be upright or inverted</p>" +
				"<p>If animation if facing left then press F " +
                "as fast as you can.</p>" +
                "<p>If animation if facing right then press J " +
				"as fast as you can.</p>" +
				"<p>Press any key to begin.</p>",
			post_trial_gap: 2000
		};
		timeline.push(instructions);

var prime_fixation_test = {
    timeline: [
        {
            type: 'image-keyboard-response',
            stimulus: jsPsych.timelineVariable('prime') ,
            choices: jsPsych.NO_KEYS,
			trial_duration: 1000,
			data: jsPsych.timelineVariable('data'),
        },
        
        {
            type: 'html-keyboard-response',
            stimulus: '+',
            choices: jsPsych.NO_KEYS,
            trial_duration: 500
        },
        {
            type: 'video-keyboard-response',
            stimulus: jsPsych.timelineVariable('test'),
            choices: ['f', 'j'],
			autoplay: true,
			data: jsPsych.timelineVariable('data'),
			on_finish: function (data) {
				data.correct = data.key_press === jsPsych.pluginAPI.convertKeyCharacterToKeyCode(data.correct_response);
        }}
    ],
    timeline_variables: [
        { test: "stimuli/Walk-90L-upright.mp4", prime: "stimuli/Grass_Inverted.jpg"},
        { test: "stimuli/Walk-90L-upright.mp4", prime: "stimuli/Grass_Upright.jpg"},
        { test: "stimuli/Walk-90L-inverted.mp4", prime: "stimuli/Grass_Inverted.jpg"},
        { test: "stimuli/Walk-90L-inverted.mp4", prime: "stimuli/Grass_Upright.jpg"},
        { test: "stimuli/Walk-90R-upright.mp4", prime: "stimuli/Grass_Inverted.jpg"},
        { test: "stimuli/Walk-90R-upright.mp4", prime: "stimuli/Grass_Upright.jpg"},
        { test: "stimuli/Walk-90R-inverted.mp4", prime: "stimuli/Grass_Inverted.jpg" },
        { test: "stimuli/Walk-90R-inverted.mp4", prime: "stimuli/Grass_Upright.jpg" },
    ],
    repetitions: 1,
    randomize_order: true,
};
timeline.push(prime_fixation_test);
        
   
		/* define debrief */
		```
var debrief_block = {
			type: "html-keyboard-response",
			stimulus: function () {

				var trials = jsPsych.data.get().filter({ test_part: 'test' });
				var correct_trials = trials.filter({ correct: true });
				var accuracy = Math.round(correct_trials.count() / trials.count() * 100);
				var rt = Math.round(correct_trials.select('rt').mean());

				return "<p>You responded correctly on " + accuracy + "% of the trials.</p>" +
					"<p>Your average response time was " + rt + "ms.</p>" +
					"<p>Press any key to complete the experiment. Thank you!</p>";

		}
	};
	timeline.push(debrief_block);

	/* finish connection with pavlovia.org */
	var pavlovia_finish = {
		type: "pavlovia",
		command: "finish",
		participantId: "JSPSYCH-DEMO"
	};
	timeline.push(pavlovia_finish);


	/* start the experiment */
	jsPsych.init({
		timeline: timeline,

		on_finish: function (data) {
			jsPsych.data.displayData();
		}
	});

</script>

```

Answered by Cluster-Bomb

Apr 7, 2021

Found a solution - see below. The plugin required the stimuli in an array. Just add brackets to the example timeline example in the documentation

timeline_variables: [
{ test: ["stimuli/Walk-90L-upright.mp4"], prime: "stimuli/Grass_Inverted.jpg"},
{ test: ["stimuli/Walk-90L-upright.mp4"], prime: "stimuli/Grass_Upright.jpg"},
{ test: "stimuli/Walk-90L-inverted.mp4", prime: "stimuli/Grass_Inverted.jpg"},
{ test: "stimuli/Walk-90L-inverted.mp4", prime: "stimuli/Grass_Upright.jpg"},
{ test: "stimuli/Walk-90R-upright.mp4", prime: "stimuli/Grass_Inverted.jpg"},
{ test: "stimuli/Walk-90R-upright.mp4", prime: "stimuli/Grass_Upright.jpg"},
{ test: "stimuli/Walk-90R-inverted.mp4", prime: "stimuli/G…

View full answer

becky-gilbert · 2021-03-30T04:30:23Z

becky-gilbert
Mar 30, 2021
Maintainer

I'm not sure, but it looks like maybe the plugin file and jspsych.js file are from different releases. Is that possible? If so, you could download one of the jsPsych releases again, point your script sources at those files, and see if that fixes the problem.

6 replies

becky-gilbert Mar 30, 2021
Maintainer

Hmm, this looks ok to me. Are you seeing any errors in the console?

It may help to preload the video and image files. Sometimes videos take a long time to load when the experiment is running on a server, so if they're not preloaded then it can seem like the trial isn't working. As of jsPsych v6.3.0, preloading is done through the preload plugin. And because you're using timeline variables, using auto_preload: true on its own won't work, so you'll need to preload the files 'manually' - this section of the preloading docs shows how to do it. Note that video preloading only works when the experiment is running on a server.

Another minor thing I noticed is that your prime and test trials reference a "data" property:

data: jsPsych.timelineVariable('data'),

but that property doesn't exist in your timeline variables objects. I'm not sure if that is causing problems. You could try commenting out the line above, or adding a "data" property to the objects in your timeline_variables array.

Cluster-Bomb Mar 30, 2021
Author

No errors - just the .mp4s won't play. I included the manual preloading and removed data property. Still nothing. I used another mp4 but it didn't play as well.

Cluster-Bomb Mar 30, 2021
Author

Tried an .avi file-type as well. No joy unfortunately.

Cluster-Bomb Apr 5, 2021
Author

Tried loading in different browsers - and still did not work - so can rule out a browser issue.

becky-gilbert Apr 6, 2021
Maintainer

Hmm. I wonder if this is something to do with the pavlovia plugin. Does it work if you remove the pavlovia_init and pavlovia_finish trials from the timeline? And what happens if you double-click on one of the video example files in the jsPsych examples folder? Do you have a live version that you could share?

Cluster-Bomb · 2021-04-07T01:58:29Z

Cluster-Bomb
Apr 7, 2021
Author

Found a solution - see below. The plugin required the stimuli in an array. Just add brackets to the example timeline example in the documentation

timeline_variables: [
{ test: ["stimuli/Walk-90L-upright.mp4"], prime: "stimuli/Grass_Inverted.jpg"},
{ test: ["stimuli/Walk-90L-upright.mp4"], prime: "stimuli/Grass_Upright.jpg"},
{ test: "stimuli/Walk-90L-inverted.mp4", prime: "stimuli/Grass_Inverted.jpg"},
{ test: "stimuli/Walk-90L-inverted.mp4", prime: "stimuli/Grass_Upright.jpg"},
{ test: "stimuli/Walk-90R-upright.mp4", prime: "stimuli/Grass_Inverted.jpg"},
{ test: "stimuli/Walk-90R-upright.mp4", prime: "stimuli/Grass_Upright.jpg"},
{ test: "stimuli/Walk-90R-inverted.mp4", prime: "stimuli/Grass_Inverted.jpg" },
{ test: "stimuli/Walk-90R-inverted.mp4", prime: "stimuli/Grass_Upright.jpg" },
],

2 replies

becky-gilbert Apr 7, 2021
Maintainer

Glad you found the solution, and sorry we didn't catch that before!

becky-gilbert Apr 7, 2021
Maintainer

Also if this is an error in the documentation, could you know what webpage or file contains the error so that we can fix it? Thanks!

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