Preventing interruptions and ensuring uniform presentation

PennController for IBEX Forums Support Preventing interruptions and ensuring uniform presentation

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  • #7055

    Hello everyone.
    I am looking for ways to prevent participants from accidentally leaving the trial or changing its presentation too much.

    1. Is there a way to prevent participants from leaving fullscreen? I already have a functions enabling fullscreen at the start of the trials and disabling it at the end (see the end of this post). But I would like to make sure that the participants stay in fullscreen mode throughout the intended experiment.
    2. Is there a way to disable the zoom function of the browser (e.g., [Ctrl]+[+]/[Ctrl]+[-] in Firefox) to ensure a uniform presentation?
    3. Is there a way to override the standard font as set by the participant’s browser?
    4. Is there a way to hide desktop notifications/popups while in fullscreen?

    I am sure there are other similar issues to reduce variability in presentation and interruptions during that I have not considered yet, but these are the ones that immediately sprung to mind.
    Thank you very much

    newFunction( ()=> {
          if (document.documentElement.requestFullscreen)
          else if (document.documentElement.mozRequestFullScreen) /* Firefox */
          else if (document.documentElement.webkitRequestFullscreen) /* Chrome, Safari, Opera */
          else if (document.documentElement.msRequestFullscreen) /* IE/Edge */
    newFunction( ()=> {
                if (document.exitFullscreen)
                else if (document.mozCancelFullScreen) /* Firefox */
                else if (document.webkitExitFullscreen) /* Chrome, Safari and Opera */
                else if (document.msExitFullscreen) /* IE/Edge */

    Hello Matthias,

    1. You cannot prevent participants from leaving fullscreen

    2. You cannot disable the zoom function of the browser

    Points 1 and 2 fall under the more general idea that scripts cannot take control away from clients (same for, eg., forcibly placing the cursor at a specific position on the page)

    3. You can use .css("font", "italic small-caps bold 12px/30px Georgia, serif") on specific elements, or add CSS rules to files in your project’s Aesthetics folder. Note that those are technically preferences: if the font is not found on the client’s system, or if the client explicitly set their browser to overwrite sites’ preferences, the browser will choose a different font (this doesn’t happen very often when you specify a standard font)

    4. I’m not sure about this one, but it sounds like it would be beyond the scope of standardized browser specifications. Each browser and/or operating system probably has settings to enable that behavior though, I guess you could invite your participants to follow instructions to manually disable notifications while in fullscreen


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