Domain: Healthcare — Skin Physiology
Target concept: Skin Microcirculation

Video generation prompt: A fair-skinned adult male placed his left forearm on the table. The experimenter first wiped the forearm with cold water at 0°C, paused for 1–2 seconds to observe changes in skin color at the wiped area, then used warm water at 50°C to wipe the same region and continued to observe the skin at the wiped area.

Evaluation guide:
(i) Target concept: Thermoregulatory microvascular response in human skin
Minimum mechanism: Skin must contain functional arterioles responsive to thermal stimuli; fair skin enables visual detection of pallor/erythema; capillary refill and blood volume changes must manifest as localized, reversible, sequential color shifts in epidermis/dermis.
(ii)Storyline: Frame 1–3: Stable static shot of left forearm on table, baseline skin tone uniform. Frame 4–6: Cloth contacts forearm → wiped region darkens (dampness) → then pales (cold-induced vasoconstriction). Frame 7–8: Cloth withdraws, pallor persists. Frame 9–10: Cloth recontacts *same region* → region remains pale → then flushes red (warm-induced vasodilation). Perspective: Fixed frontal/slightly oblique view; full forearm in frame; no occlusion of wiped region; lighting front-diffuse to maximize color contrast.

Manual:
Experimental Procedure
1. A fair-skinned adult male places his left forearm stationary on a table.
2. Experimenter wipes a defined region of the forearm with a damp cloth soaked in cold water (0°C).
3. After 1–2 seconds, experimenter wipes the *same region* with a damp cloth soaked in warm water (50°C).
Observation of Experimental Phenomena
- Immediately after cold wipe: wiped region becomes visibly paler than surrounding skin.
- After warm wipe: wiped region becomes visibly redder than surrounding skin.
Summary of Experimental Principles
Cold induces arteriolar vasoconstriction → reduced blood flow → pallor. Warmth induces arteriolar vasodilation → increased blood flow → reactive hyperemia → erythema. Demonstrates neural and local thermal regulation of skin microcirculation.

Prompt Grounding rubric:
level_1: No adult male forearm is shown; no wiping action occurs; neither cold nor warm water application is depicted; no table surface appears under the arm; essentially none of the core setup elements from the prompt are present.
level_2: Some setup elements appear (a forearm, a table, or a hand holding a cloth or water source), but there is no clear sequence of two separate thermal wipes; the cold and warm applications are not visually distinguishable from each other; and there is no indication that the same region is wiped twice.
level_3: The left forearm rests on a table and is wiped in two separate, sequential events (first a cold-water wipe, then a warm-water wipe), each involving a cloth or similar tool making contact with the skin; the subject is a male adult forearm as specified, not a different limb or a different person.
level_4: Everything required at the 3-point level holds, and additionally both wipes contact the same visible patch of the forearm; the same cloth, or a visually matching one, is used for both wipes; the experimenter's hand is visible performing both wipes; no extra actions (rubbing elsewhere, spraying, touching a different spot) interrupt the two-step sequence.
level_5: Everything required at the 4-point level holds, and additionally the forearm stays completely still (no lifting, repositioning, or rotating) for the whole recording; the experimenter's hand enters frame for the first wipe, leaves, then returns the same way for the second wipe; the table and the arm's orientation look the same throughout; there is no cut, zoom, or camera-angle change between the two wipes.

Scientific and Causal Correctness rubric:
level_1: The wiped patch of skin never visibly changes color throughout the recording, staying the same tone as the surrounding untouched skin the whole time; or the color response is scientifically backwards (redness follows the cold wipe, or pallor follows the warm wipe).
level_2: Only one of the two expected color changes appears (either pallor after the cold wipe, or redness after the warm wipe, but not both); or the single visible color change follows the wrong stimulus (e.g., redness appears after the cold wipe, or pallor appears after the warm wipe); or a color change occurs but spreads well beyond the wiped region rather than staying localized to it.
level_3: Two distinct, separated color changes occur in the wiped region: pallor (whitening) develops shortly after the cold wipe, and redness (flushing) develops shortly after the warm wipe; both changes stay confined to the wiped area without spreading to the rest of the forearm.
level_4: Everything required at the 3-point level holds, and additionally the pallor phase is clearly lighter than the surrounding unwiped skin, and the redness phase is clearly redder than both the baseline skin tone and the pallor phase; no unrelated hue (such as purple, yellow, or grey-blue mottling) appears in the wiped region during either phase.
level_5: Everything required at the 4-point level holds, and additionally: pallor appears only after the cold wipe and persists through the pause before the second wipe, with no early return to baseline skin tone; once the warm wipe is applied, the pallor gives way to redness through a brief but visibly continuous transition (not an instant single-frame swap), and the redness then fully replaces the pallor with no relapse back to paleness; the wiped region never shows pallor and redness mixed together at once.

Spatiotemporal Consistency rubric:
level_1: The forearm, the table, or the wiping cloth vanishes and reappears, or jumps to a different position without any visible motion connecting the two states; the lighting shifts abruptly (e.g., from bright daylight to near-darkness) with no visible cause; the view suddenly cuts to a different angle or distance; the arm's outline shows an impossible kink, fold, or break between frames.
level_2: The forearm shifts position or rotates more than about 15 degrees between the two wipes without a smooth motion connecting the change; the cloth changes size, shape, or orientation between frames without a visible reason; the wiped region's boundary stretches, shrinks, or ripples during contact rather than keeping a stable outline.
level_3: The forearm shows a slight tremor or breathing-related motion; the wiped region's boundary is stable in shape and location across both wipes, though a faint, brief flicker in overall image brightness is noticeable at one or two points in the recording; none of these amount to the arm changing position, the cloth changing shape, or the wiped region relocating.
level_4: Everything required at the 3-point level holds, and additionally the forearm shows no detectable translation, rotation, or flexing relative to the table between the two wipes; the cloth keeps a consistent shape and contact angle during each wipe; the overall brightness and the direction of the main light source stay the same from the first frame to the last; the wiped region shows no flicker or jitter in its outline.
level_5: Everything required at the 4-point level holds, and additionally: the wiped region's outline stays in the same location and shape before, during, and after each wipe, with no visible drift; the background behind the forearm does not shift relative to the arm; and no frame shows blurring, doubling, or ghosting of the arm, cloth, or table that would suggest a duplicated or dropped frame.