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+--- Thread: Audiovisual stimulus presentation (/showthread.php?tid=836)
Audiovisual stimulus presentation - HF2021 - 10-29-2025
Hello all,
I have a question about how to properly set up an audiovisual stimulus in a two-alternative forced-choice task. Any help or guidance on this would be much appreciated!!
In simple terms, the stimulus will contain an audio signal, for example, the spoken word “Myth”, and a visual component that shows two response options, two words, for example “Miss” and “Myth” on the left and right side of the screen. The participant has to choose between the two displayed words to match the audio signal they heard. The way we have currently set this up allows two words on screen by creating this response option:
{
"type": "choice",
"choices": [
"S",
"T"
],
"key_mapping": [
"S",
"T"
],
"key_only": true,
"hint": true,
"target": "T",
"feedback": false,
"feedback_audio": false,
"instruction": ""
}
This will allow the participant to either press the “T” button on the keyboard for “Myth” or the “S” key for “Miss”. Here’s the problem: currently, on the screen there will be the two choices “S” and “T” shown. What we would like to do is to have the two WORDS displayed (Myth and Miss). The pairs of words change on every trial but always involves a choice between a T sound and an S sound. The issue is that this response setup is static and will always only display “S” and “T” as options, not the actual two words that will change on every trial. Is there a way to set up the response or stimulus in a way that dynamically accepts two words as the two options that correspond to the audio signal (which changes on every trial). Thank you, and apologies if this is a simple question with an obvious answer.
The stimulus setup is currently something like this:
{
"type": "audio",
"content": "myth.wav",
"barrier": false,
"visible": false
}
RE: Audiovisual stimulus presentation - noah.nelson - 10-29-2025
Hello HF2021!
You have a couple options for how to achieve your desired result:
1. Build a different response for every trial and put the target and foil WORDS in as the choices, instead of "S" and "T"
The basic logic here is that you make a new response for each word pair, and explicitly put the words in as the choices. If you didn't already know, you can set up a trial template with N trials, each using one of N responses. For example, a template with N audio stimuli and N responses will, by default, pair each response to a stimulus in order (stim1+resp1, stim2+resp2, ...stimN+respN). In this way, you can ensure that "myth.wav" is correctly matched up with the "MYTH / MISS" 2AFC choice response. This pairing of stimuli and responses into trials happens before the stimulus_pattern is applied, so you can still randomize this and be sure that your stimuli and responses will match on each trial. See this resource for more information on default and custom response pairing options in trial templates.
2. Build additional text stimuli for each word and display them along with the response
The basic logic here is to have each trial consist of 1 audio stimulus, 2 text stimuli (your target and foil words), and 1 choice response (your S/T 2AFC). By default the two words should appear side-by-side, and if they don't you can use the custom layout option to specify their locations. However, the spacing between the two words might be a bit tighter than you'd like. You can adjust the size of the text stimuli to help with this, but depending on your desired trial layout you may need to use a hack to space the words out.
Basically, if you have a compelling reason to want your response choices to always be "S" and "T", then option 2 is likely your best bet. In this case, let me know and I can help you with the "hacky" solution for spacing out the words. But I would strongly suggest option 1 if it fits your design needs. This is certainly what I would do!
Best of luck, and please follow up here as needed or to let us know how it goes!
RE: Audiovisual stimulus presentation - HF2021 - 10-30-2025
Dear Noah,
Thank you so much for this detailed answer. It is very helpful!!
We'll start with option 1 as you suggest since it seems like a cleaner design. The study involves the perception of accents, and specifically the difference between the "s" and "th" sounds, and while the word pairs displayed change on every trial (Myth-Miss; Seem-Theme, etc.), the response options on the keyboard will be "S" or "T". Still, we'll start with option 1 per your suggestion and see how it goes!
Many thanks!!
Haleh
RE: Audiovisual stimulus presentation - noah.nelson - 10-30-2025
Oh, hi Haleh!
I'm glad to hear this was helpful. Best of luck with the research!
RE: Audiovisual stimulus presentation - HF2021 - 10-30-2025
Option 1 works! Awesome! Thank you!