Domain: Humanities and Social Sciences — Arts
Target concept: Color constancy under varying lighting conditions (a single object illuminated by light ranging from warm to cool tones)

Video generation prompt: A red apple is placed on a white tablecloth, with the room's lighting smoothly transitioning from warm yellow to cool blue.

Evaluation guide:
(i) Target concept: Color constancy under varying correlated color temperature illumination.
Minimum mechanism: Color constancy is a perceptual phenomenon: a viewer watching the scene continues to read the apple as red and the tablecloth as white even though the light physically reflected from each surface does shift toward the ambient color temperature (a warmer, yellow cast under ∼2700K light, a cooler, blue cast under ∼6500K light). A physically faithful rendering should therefore show this real illuminant-driven tint on both surfaces, rather than literally unchanging pixel colors (which would itself be unrealistic), while keeping each object within its original hue family (the apple staying recognizably red and the tablecloth staying a recognizably light, near-neutral surface), so a viewer never mistakes either object for a different color entirely.
(ii)Storyline: [Frame 0–3] Warm yellow light bathes the red apple and white tablecloth, giving both a warm cast → [Frame 4–7] Illumination gradually cools, with no change in apple placement or tablecloth position, and the warm cast on both surfaces gradually gives way to a cooler one → [Frame 8–10] Cool blue light fully dominates, tinting the apple and tablecloth accordingly, yet the apple still reads clearly as red and the tablecloth still reads clearly as white rather than shifting into a different hue family; all transitions occur from a fixed frontal viewpoint with no camera motion, occlusion, or object repositioning.

Manual:
Experimental Procedure
1. Place a single red apple on a white tablecloth.
2. Illuminate the scene with warm yellow light.
3. Smoothly transition illumination to cool blue light over the full duration.
Observation of Experimental Phenomena
Both the apple and the tablecloth visibly pick up a tint that tracks the ambient light's color temperature — a warm yellow cast while the warm light dominates, a cool blue cast while the cool light dominates — yet the apple remains recognizable as red and the tablecloth remains recognizable as white/off-white throughout; the illuminant-driven tint changes each surface's appearance without pushing either object into a different hue family.
Summary of Experimental Principles
Color constancy is the perceptual phenomenon whereby a viewer perceives an object's color as relatively stable across changes in illumination, even though the light physically reflected from the object's surface does shift with the illuminant's spectral composition; the visual system compensates using contextual cues (the visible light source, surrounding surfaces) so that the object's categorical color identity — e.g., 'red apple', 'white tablecloth' — is preserved despite this real, measurable tint shift.

Prompt Grounding rubric:
level_1: No red apple is present, or no white tablecloth is present, or no lighting transition is visible, or the lighting transition does not involve a shift from a warm yellow tone to a cool blue tone, or the apple is not resting on the tablecloth.
level_2: The red apple and white tablecloth are both present and the apple rests on the tablecloth, but the lighting transition is missing, or only one lighting tone (warm or cool) appears without any transition between them.
level_3: The red apple rests on the white tablecloth and the lighting visibly transitions from a warm yellow tone to a cool blue tone as a continuous change spanning the whole scene.
level_4: Everything required for a 3 holds, and in addition, at the start of the clip, before the lighting shift begins, the apple reads as a clear, saturated red (not orange, pink, or brown) and the tablecloth reads as a clear white or off-white (not cream, gray, or patterned), establishing an unambiguous baseline for both objects.
level_5: Everything required for a 4 holds, and in addition, the warm-yellow phase and the cool-blue phase of the lighting are each clearly identifiable as their own distinct color temperature (the warm phase visibly yellow-toned, the cool phase visibly blue-toned, rather than both looking like similar neutral-white light), and the apple sits roughly centered on the visible tablecloth rather than at its edge or partly off it.

Scientific and Causal Correctness rubric:
level_1: The apple and tablecloth show no perceptible response to the changing light at all, looking the same color throughout as if lit by neutral white light despite the yellow-to-blue shift; or the apple shifts into a hue family unrelated to red (e.g., fully green, purple, or gray); or the tablecloth shifts into a fully saturated color rather than staying a light, near-neutral surface.
level_2: The apple and tablecloth do pick up some tint from the changing light, but the response runs backwards or is inconsistent: for example, the apple looks cooler/bluer under the warm-yellow light and warmer/redder under the cool-blue light (the reverse of what the ambient color temperature would produce), or one surface tints noticeably while the other stays completely unaffected despite receiving the same light.
level_3: Both the apple and the tablecloth pick up a visible tint that matches the direction the ambient light would actually produce (warmer/yellow-tinted while the warm-toned light dominates, cooler/blue-tinted while the cool-toned light dominates), and despite this tint the apple's hue stays within the red family (crimson, scarlet, brick, cherry) rather than reading as orange, brown, or magenta.
level_4: Everything required for a 3 holds, and in addition, the tablecloth likewise keeps its identity as a light, near-neutral surface throughout: under the warm phase it reads as a white cloth with a yellow cast, under the cool phase as a white cloth with a blue cast, but at no point does it read as fully yellow, fully blue, or fully gray the way a saturated colored fabric would.
level_5: Everything required for a 4 holds, and in addition, the tint on both the apple and the tablecloth tracks the lighting change smoothly and matches the same lighting phase at every moment (the apple and tablecloth are never tinted warm while the visible light source looks cool, or vice versa), so a viewer would consistently identify them as the red apple and the white tablecloth under believably shifting light rather than under flat, unchanging illumination.

Spatiotemporal Consistency rubric:
level_1: The apple or the tablecloth disappears, teleports, rotates, or changes size or shape mid-transition, or the lighting change happens via an abrupt cut or flash instead of a smooth progression.
level_2: The lighting transition is continuous but contains at least one visible discontinuity: a sudden brightness jump, a shadow that flickers, or a localized patch of light that appears or disappears without explanation.
level_3: The apple stays fixed in its position on the tablecloth throughout; the lighting transition proceeds continuously with no cuts, flashes, or teleportation; and the tablecloth's surface keeps a consistent texture and flatness across the whole clip.
level_4: Everything required for a 3 holds, and in addition, the lighting gradient evolves evenly across the whole scene, with no isolated hotspots or shadows that fail to shift with it, and neither the apple nor the tablecloth shows any warping, stretching, or perspective distortion.
level_5: Everything required for a 4 holds, and in addition, motion parallax and occlusion relationships stay stable throughout: no unintended shimmer along the apple's or tablecloth's edges, no moment where the apple appears to float above the cloth, and no inconsistency in the cast shadow's direction or softness as the lighting shifts.