Domain: Healthcare — Skin Physiology
Target concept: Comparison of swollen ankle with normal ankle under pressure

Video generation prompt: A seated adult exhibits a swollen ankle positioned side by side with a normal ankle, while a clinician applies pressure with the thumb at corresponding locations on both ankles and then releases it.

Evaluation guide:
(i) Target concept: Differential tissue compliance under mechanical pressure in edematous vs. healthy dermal/subcutaneous tissue.
Minimum mechanism: Swollen tissue must contain excess interstitial fluid that impedes elastic recoil; normal tissue must possess intact extracellular matrix enabling instantaneous shape restoration.
(ii)Storyline: Frame 1–2: Static side-by-side view of seated adult with swollen and normal ankle aligned medially. Frame 3–4: Clinician"s thumbs approach and settle onto corresponding medial malleoli. Frame 5–6: Thumb pads visibly depress swollen ankle skin; no depression on normal ankle. Frame 7–8: Thumbs lift away simultaneously; swollen ankle indentation remains static; normal ankle surface restores fully by Frame 9. Perspective: Fixed frontal mid-calf view; both ankles fully in frame, unoccluded, consistent lighting; no camera motion; clinician"s hands enter from bottom edge and remain below ankle level to avoid occlusion.

Manual:
Experimental Procedure
1. Seat adult facing camera, legs extended forward, feet flat on floor.
2. Position swollen ankle and contralateral normal ankle side-by-side, medial surfaces fully visible.
3. Clinician places thumb pads simultaneously on medial malleolus of both ankles.
4. Apply firm, steady pressure for ~1 second, then release completely.
Observation of Experimental Phenomena
- Swollen ankle shows visible indentation during pressure and retains indentation after release.
- Normal ankle shows no indentation during pressure and fully rebounds instantly upon release.
Summary of Experimental Principles
Swelling reflects interstitial fluid accumulation in edematous tissue, reducing tissue elasticity and delaying recoil; normal tissue exhibits rapid, complete elastic recovery due to intact collagen-elastin matrix and low fluid volume.

Prompt Grounding rubric:
level_1: No seated adult is shown; the swollen ankle and normal ankle are never both present in the frame; no clinician appears; the thumb never makes contact with either ankle; the two ankles are never shown together for comparison.
level_2: A seated adult and both ankles are visible, but the swollen and normal ankle are shown one at a time rather than together in the same frame; or the clinician's thumb touches only one of the two ankles; or the thumb contacts non-matching spots (e.g., the medial side of one ankle and the lateral side of the other).
level_3: A seated adult is shown with the swollen ankle and normal ankle visible together in the same frame; the clinician's thumb contacts both ankles at the same anatomical spot (the medial malleolus) either at the same moment or in quick succession; the thumb is then lifted away from both ankles.
level_4: All conditions for score 3 are met, and additionally: neither ankle shifts position or is blocked from view during the contact-and-release sequence; the clinician's thumb keeps a steady orientation and visibly presses into the swollen ankle's skin while resting on the normal ankle without producing a matching press mark.
level_5: All conditions for score 4 are met, and additionally: the swollen and normal ankle stay together in view, at the same relative position to each other, from the first frame to the last; the thumb touches down on both ankles in the same frame and lifts away from both in the same frame; the medial malleolus contact point on each ankle remains fully visible and unobstructed by the clinician's fingers throughout the entire sequence.

Scientific and Causal Correctness rubric:
level_1: The swollen ankle and normal ankle look the same size and shape; thumb pressure leaves no mark on either ankle, or leaves the same kind of mark on both; there is no visible sign that swelling changes how the tissue responds to pressure.
level_2: The swollen ankle looks larger than the normal ankle, but this difference is inconsistent across frames or hard to make out; thumb pressure produces a visible pit on both ankles or on neither; where a pit does appear, both ankles smooth back out in the same way, so no swelling-related contrast is shown.
level_3: The swollen ankle is clearly and consistently larger than the normal ankle; thumb pressure leaves a visible pit only on the swollen ankle's skin, not on the normal ankle; once the thumb lifts away, the normal ankle's surface smooths back out right away, while the swollen ankle keeps its pit rather than filling back in immediately.
level_4: All conditions for score 3 are met, and additionally: the pit on the swollen ankle is noticeably deeper or clearer than anything on the normal ankle; the normal ankle finishes smoothing out before the swollen ankle shows any sign of filling back in; the swollen ankle's pit does not briefly bulge or ripple in a way that could pass for recovery.
level_5: All conditions for score 4 are met, and additionally: a pit appears on the swollen ankle only, at every moment pressure is applied, and never appears on the normal ankle; the swollen ankle's pit stays visibly unchanged through the last frame of the clip, showing no gradual filling-in, while the normal ankle shows a fully smooth surface with no lingering mark at any point after release; both ankles stay in view together so this contrast is never hidden by the clinician's hand or by cropping.

Spatiotemporal Consistency rubric:
level_1: One or both ankles jump to a different position or vanish between consecutive frames; the clinician's hand or thumb disappears and reappears without a visible transition; either ankle's shape warps or distorts abruptly partway through the sequence; the lighting suddenly shifts or shadows jump with no cause (e.g., bright to dark within a single frame); the camera framing or zoom changes abruptly without a smooth transition; the background changes discontinuously.
level_2: A brief one-frame stutter occurs in the thumb's approach or retraction; the clinician's hand momentarily blocks one ankle from view in a way that briefly breaks continuity; the camera drifts slowly (an unintended pan or tilt) that shifts the ankles' apparent alignment without any hard cut.
level_3: Neither ankle teleports or breaks shape at any point; the camera framing, zoom, and crop stay constant throughout; the two ankles keep the same position relative to each other from start to finish; the clinician's hand and thumbs stay visible and move in an anatomically plausible path.
level_4: All conditions for score 3 are met, and additionally: the thumb's approach, contact, hold, and retraction on both ankles forms one smooth, uninterrupted motion; neither ankle nor the clinician's hand shows tearing, ghosting, or a disconnected/floating-limb look; both ankles stay on a consistent visual depth relative to the camera, with no sudden change in relative size suggesting either one moved closer or farther away.
level_5: All conditions for score 4 are met, and additionally: no motion blur obscures the moment the thumb makes contact, the moment it lifts away, or the earliest sign of the normal ankle's rebound; no frame is skipped or duplicated in a way that would break the contact-then-release order; the two ankles keep the same relative size, spacing, and which one appears closer to the camera from the first frame to the last.