I need help designing an experiment where participants iteratively adjust video stimuli using two unlabelled sliders (5 discrete levels each). Videos are pre-rendered (not manipulated in real-time). Participants must watch each video fully before adjusting.
Stimuli: 25 base videos × 5 speed levels × 5 complexity levels = 625 variants.
Trial Flow:
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Randomly select one of the 625 videos.
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Participant watches the full video (centered), flanked by:
Horizontal slider (speed adjustments).
Vertical slider (complexity adjustments). -
After watching, they adjust one/both sliders → updated video plays.
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Repeat adjustment (or press ‘space’ to finalize).
How can I efficiently handle the 625-video mapping while implementing discrete slider adjustments, triggering video updates?
More specifically,
- How can I structure my Loops to allow participants to adjust sliders multiple times per trial (updating the video dynamically) without advancing the Loop iteration?
- Should my conditions file list all 625 video variants explicitly (e.g., one row per combination), or can I use formulas in Excel to auto-generate the video_path column?
- After a slider adjustment, how do I force the experiment to reload the new video variant (e.g., from Base1_Speed2_Complexity3.mp4 to Base1_Speed4_Complexity3.mp4) within the same trial? Does this require a code component to overwrite the Loop’s condition variables mid-trial?