Multiple stims on trial but presented sequentially

[atfrederiksen]

I would like to present videos in different length sequences. That is, on one trial, participants see one video before they respond. In another, they see 2 or 3 or 4 before responding. I tried grouping the vide stimuli within the trial template (e.g., [[vid 1, vid 2], [vid 3, vid 4, vid 5]], but then the first video stays visible when the next starts to play, which I would like to avoid. What other ways are there of achieving this?

[Ting]

Hi - our team is experimenting with a potential solution. Will reach out back soon!

[mt_FF]

Hello! Here is the solution we came up with.

First, create trial templates for stimuli and responses only. To do this, you can leave "responses" and "stimuli" parameters blank, respectively. You should create multiple stimulus templates as some trials present 1 video and others present 2, for example, in your design. Here's what those templates would look like.

{
  // A separate template with only the desired response
  "Response_Template": {
    "type": "basic",
    "stimuli": [],
    "responses": ["rate"]
  },
  // A separate template for the string of only 1 video
  "Stimulus_Template_1_video": {
    "type": "basic",
    "stimuli": ["example_video_stimulus"],
    "responses": [],
    "auto_advance": true
  },

...  // Make separate templates for the string of 2 videos, 3 videos, and so on

Now, you have two options as to how to configure your procedure.

Option 1: Create a single block with manual placement of response trial template, like the following:

"ALL_video_presentation_block": {
        "trial_templates": [
          "Stimulus_Template_1_video",
          "Response_Template",
          "Stimulus_Template_2_videos",
          "Response_Template",
          "Stimulus_Template_3_videos",
          "Response_Template"
        ]
      },

Option 2: Create multiple blocks for stimulus templates, and use the response template as end trials for the separate blocks, like the following:

"ONE_video_presentation_block": {
        "trial_templates": ["Stimulus_Template_1_video"],
        "end_trials": ["Response_Template"]
      },
      "TWO_video_presentation_block": {
        "trial_templates": ["Stimulus_Template_2_videos"],
        "end_trials": ["Response_Template"]
      },

... // and so on

You can choose whichever option that works better for your design.

I hope this helps, and please let us know if you have any clarification questions.