Domain: Humanities and Social Sciences — Arts
Target concept: Oil Painting - Color

Video generation prompt: Display a palette on which the artist has placed equal amounts of red and yellow pigment, and gently mixed them using a palette knife.

Evaluation guide:
(i) Target concept: Subtractive pigment mixing of primary colors to produce a secondary color.
Minimum mechanism: Two opaque, spectrally distinct pigment masses must be in physical contact; a rigid tool must mediate mechanical intermingling; resulting hue must emerge solely at the interface due to optical averaging of reflected light from mixed particles.
(ii)Storyline: Frame opens on static palette with isolated red and yellow blobs (adjacent, non-overlapping). Palette knife enters frame and contacts red blob → moves continuously across boundary → contacts yellow blob. During boundary-crossing motion, orange region appears *only* along knife path. Knife withdraws; red, yellow, and orange regions persist with stable spatial relationships. Viewpoint is fixed frontal-medium close-up; all elements remain fully visible and unoccluded throughout.

Manual:
Experimental Procedure
1. Place a clean artist"s palette in frame.
2. Deposit one distinct red pigment blob and one distinct yellow pigment blob side-by-side on the palette surface.
3. Use a palette knife to gently draw the blade across the boundary between the two blobs.
Observation of Experimental Phenomena
A new orange-colored region appears exclusively at the location where the knife crossed the interface between red and yellow; red and yellow remain visually distinct outside this region.
Summary of Experimental Principles
In oil painting color theory, red and yellow are primary pigments; their physical mixture produces orange — a secondary color — via subtractive color mixing governed by pigment absorption spectra.

Prompt Grounding rubric:
level_1: No palette is visible; neither red nor yellow pigment is present; no palette knife is visible; no mixing action is attempted.
level_2: The palette is visible and at least one of the red or yellow pigment blobs is present, but the other pigment is missing, or the palette knife never appears in frame; no contact between knife and pigment is shown.
level_3: The palette is visible with both red and yellow pigment shown as distinct, adjacent, non-overlapping blobs; the palette knife is visible and touches at least one of the two blobs; the two pigments have not yet been drawn together.
level_4: All of 3-score, plus the palette knife visibly contacts both the red and the yellow blob (simultaneously or in sequence) and visibly drags across the boundary between them; the palette, pigments, and knife stay in a fixed spatial arrangement relative to each other throughout, with neither blob relocated between shots.
level_5: All of 4-score, plus red and yellow are placed with roughly equal visual prominence (neither blob is much larger or more saturated than the other) before mixing begins; no object (palette, pigment, or knife) enters or exits the frame at any point; the camera holds a fixed frontal, medium-close framing of the palette for the whole clip.

Scientific and Causal Correctness rubric:
level_1: No color change occurs anywhere on the palette; red and yellow stay fully separate with no visible interaction at their boundary; no orange ever appears; if any blended patch does appear, its hue is clearly wrong (e.g., green, purple, or gray) rather than orange.
level_2: An orange patch appears, but it is not located where the knife has worked the red-yellow boundary (e.g., it floats away from both blobs, sits on the knife handle, or appears along the palette rim); or an orange patch appears before the knife has touched either pigment.
level_3: Orange appears only where the knife has worked the boundary between red and yellow, but streaks of the original red or yellow are still visible running through the orange patch, or the orange patch spreads out well beyond the area the knife actually touched.
level_4: Orange appears only at the knife-worked boundary between red and yellow; the orange color looks consistent across that patch and is clearly a different color from both the red and yellow pigment; no visible red or yellow streaks remain within the orange region; the orange patch grows continuously as the knife keeps moving, tracking the knife's path; no unrelated color (e.g., a black smudge or white streak) appears within the blended patch.
level_5: All of 4-score, plus the orange only appears after the knife begins working the boundary, never before; the orange patch's outline stays confined to the area the knife has actually passed over; its hue reads as a plausible orange, clearly distinct from both source reds and yellows, without drifting to look too red or too pale/yellow as the mixing continues; the pigment does not appear to darken, lighten, or wash out in a way inconsistent with simple red+yellow pigment mixing.

Spatiotemporal Consistency rubric:
level_1: The palette, pigment blobs, or knife blink out of view and then reappear, or jump to a different spot on screen with no motion in between; the knife's motion skips discontinuously from one pose to another; the palette surface itself bends, stretches, or breaks apart at any point; the lighting or shadow across the palette shifts abruptly (e.g., a shadow disappears then reappears) with no cause.
level_2: The palette stays visible but is stretched, skewed, or flips orientation partway through the clip; the knife changes size or rotates unnaturally between frames; the pigment appears to flow like a liquid rather than behaving like a paste; the blended orange patch blinks on and off rather than growing continuously.
level_3: The palette stays in the same place and at the same size on screen throughout; the red and yellow blobs keep their shape and position until the knife reaches them; the knife travels in one continuous, unbroken motion from one pigment to the other; the orange patch grows in step with the knife's path length; the knife never appears to pass through a pigment blob without visibly displacing or blending it.
level_4: All of 3-score, plus the knife's speed and path look physically natural, without sudden jerks, pauses, or unexplained bursts of speed; the orange patch's growth stays tied to the knife's visible motion at every point, with no orange appearing ahead of or behind where the knife has actually traveled; no object's outline tears, doubles, or stutters between frames.
level_5: All of 4-score, plus the outlines of the palette, the pigment blobs, and the knife blade show no visible shifting or warping of shape across frames; the knife moves at a steady, even pace while in contact with the pigments, without visible speed changes; any shadow or highlight cast by the knife or pigment shifts smoothly in step with the knife's own motion rather than jumping or freezing; no part of any object appears to stretch, shear, or distort at any time.