Preloading set of images per trial

[NadineDijkstra]

Hi hi, I am setting up an experiment in which I want to show a set of 20 images for 100 ms each - the images are different every trial. I am using the jspsych-animation plugin which works like a charm but sometimes the server is too slow and it shows an image-pictogram instead of one of the images. I know I could preload all images at the start of the experiment with the jspsych-init function but in my case that would be way too many. Is there a way to preload a set of images prior to every trial (e.g. in the ITI) and then remove them again? Thanks!

[vijaymarupudi]

Before a trial with images, or a block of trials, you can use the call-function plugin to preload the images. I'm using getDisplayElement() and pluginAPI.preloadImages()

var images = ["image1.png", "image2.png"]

var trial = {
  type: "call-function",
  async: true,
  func: function(done) {
    jsPsych.getDisplayElement().innerHTML = '<p>Loading... Please wait.</p>'
    jsPsych.pluginAPI.preloadImages(images, function() {
      done({ preload: "success" });
    })
  }
};

[vijaymarupudi]

When you use timeline variables in a function, the second parameter should be true.

See second example under here.

[NadineDijkstra]

Thank you that helps! It now works most times but every now and then, seemingly random, I get a message that says 'experiment failed to load'. Can you think of what would be going wrong there?

[NadineDijkstra]

Also, I just saw that the animation plug-in that I am using has the following code:

jsPsych.plugins.animation = (function() {

  var plugin = {};

  jsPsych.pluginAPI.registerPreload('animation', 'stimuli', 'image');

Doesn't that mean that the stimuli should be preloaded automatically when I run this function?

[vijaymarupudi]

Do you see any errors in the console when "experiment fails to load" shows up?

That function registers it to preload at the beginning of the experiment, it doesn't preload immediately.

[NadineDijkstra]

Ah I wasn't aware of the console error reporting :') This helps a lot, thanks, it's working now!