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How to present stimuli files randomly to participants?

overtone Community Member Qubie ✭

Dear Community,

in my survey I am going to present a total of 100 different acoustic stimuli (recorded as short wav files) and ask the participants to evaluate them pairwise (which sound do you prefer: A or B?; then repeat this question with a different pair of stimuli). The issue is that these sounds come from three distinctive groups and each group has a different amount of stimuli (e.g. 25, 35 and 40). For every trial I would like Qualtrics to randomly pick out one sound from one of the three groups and one sound from a different group. After e.g. 30 trials, each group must have appeared equal amount of times with its stimuli (in this case 20 stimuli of each group).
Is there any way to do it? I would really appreciate your help! I could actually generate a block of 100 questions and randomise them. But the issue is that I'd like to present two randomly chosen files in one question. The second problem is that the pair must consist of sounds from different groups.

Thanks a lot in advance!

Best Answer

  • Akdashboard
    Akdashboard South CarolinaCommunity Member Superuser ✭✭✭✭
    Accepted Answer

    @overtone - What a fun thought experiment! Read the entire section before doing any programming, I have 1 small tweak included under "HOW TO INTERPRET YOUR DATA" that is important to know from the beginning.

    You can do this, but it will take a little bit of programming in the survey flow.

    First, you need to make your sound files embedded data fields. The cleanest way to do this would be to save them to your Qualtrics library and then copy the file URL to equal the value of specific sound file. Notice that in the image below, the embedded data field NAME is the same (Sound File 1), just the value the populates the file is different. Within the same embedded data element, add an embedded data value called "Selected Block".

    Next, you will need to create 3 randomizer blocks with 25, 35, and 40 embedded data elements nested under the 3 blocks respectively. For "Randomly Present [] of the following elements" set [] to "1". Within each block, set "Block Selected" to either 1, 2, or 3 depending on which randomizer the block is nested under . The image example i use only has 2 embedded data elements for simplicity.

    Next, you need to create a fourth randomizer block and nest the 3 randomizers under it. Set this block to randomly present "1" elements also. This will present 1 of the next tier of elements of nested this elements, i.e. 1 of the 3 randomizer, which in turn will randomly generate 1 the nested embedded data elements.


    Next, duplicate all these blocks by selecting "duplicate" from the top tiered randomizer block. Then change the embedded data field "Sound File 1" to "Sound File 2".
    You can skip this next part if you don't care if the respondent receives 2 files from the same block (i.e. 2 sound files from the list of 25)
    Above each nested randomizer, add a branch block and use this logic: Branch if Embedded Data IS NOT EQUAL to Block 1 | Repeat for blocks 2 and 3.

    Lastly in the Survey flow, set an embedded data element under you survey question block with 2 fields: Selected Choice and Note Selected Choice and set each value to be equal to the survey question "Selected Choices" and "Unselected Choices" respectfully.

    The entire flow will look like this but with WAY more embedded data elements.

    FINALLY, use piped text to pipe in the randomly selected sound files to your survey question. Note that "%20" just means a space exists.

    FINALLY FINALLY - You may need to tweak the html in order for the sound file to actually appear. To do this, go to the Rich Content editor for your choice selection and click the "source" button.

    The goal here is to use piped text to pipe in the randomly selected sound file without needing to build a ton of questions. Where the URL would ordinarily be, just copy and paste the piped text logic. - I don't have a picture because I don't know how you set up your question and I don't want to confuse you further.

    Selected Choice and Not Selected Choice will say either OPTION 1 or OPTION 2. OPTION 1 equates to Sound File 1 and OPTION 2 equates to Sound File 2. So, if Selected Choice is equal to Option 2, that means they selected Sound File 2 over Sound File 1... both will have the URL for the sound file you included. To make life easier, you may want to add a third embedded data element alongside Sound File 1/2 and Select Block 1/2/3 called "File Name 1" and "File Name 2" (respectively) with a more user-friendly name for the sound files.

    See my image as an example. Sorry, I am not fixing all my above images as this isn't strictly necessary, it will just make you life A LOT easier.


  • overtone
    overtone Community Member Qubie ✭

    Thank you so much Patrick! It is such a great help! I will immediately try it out today. Actually, I have some programming skills in MATLAB, but basically none in HTML or Java. But logically I can follow the steps:)
    Best greetings from Austria!

  • overtone
    overtone Community Member Qubie ✭

    And the last question: How to repeat the whole question 20 times (each time a new pair to be generated) and for each time the selected choice should be recorded. Thanks!!!