Domain: Natural Science — Morphology
Target concept: A commonly cited (though not rigorously quantified) visual impression in eastern gray squirrels: males are often described as having bushier, longer-looking tails than females in North American forest populations. This is used here as an illustrative visual comparison rather than a validated sexing method, since sex in this species is reliably determined by anogenital inspection rather than tail appearance.

Video generation prompt: The screen displays two columns: the left shows a female gray squirrel from a North American forest population, and the right shows a male gray squirrel from the same population. The images highlight the tail characteristics of the two squirrels, comparing the proportions and lengths of their tails.

Evaluation guide:
(i) Target concept: A commonly cited but not rigorously validated visual impression that male eastern gray squirrels (Sciurus carolinensis) have bushier, longer-looking tails than females; this is depicted here as an illustrative visual comparison rather than an established sexual dimorphism, since sex in this species is not reliably distinguishable by tail appearance and is instead determined by anogenital inspection.
Minimum mechanism: Squirrels must be adult, healthy, unmanipulated individuals exhibiting natural resting posture; any tail-appearance difference shown must arise from intrinsic anatomy or posture (fur density, length, musculature), not external factors (wind, grooming, camera angle); the video illustrates the commonly cited impression rather than claiming it reliably predicts sex.
(ii)Storyline: Frame 1–10: Static, synchronized frontal view of two squirrels, left (female) and right (male), fully in-frame, tails unoccluded. Key causal transitions: (1) Presence of two conspecifics establishes comparability; (2) Side-by-side placement enables direct visual contrast; (3) The commonly described tail-appearance contrast (fluffiness + relative length impression) emerges passively from static anatomy; no action required beyond display. Perspective constraint: Strictly frontal, orthographic-like, fixed viewpoint; visibility constraint: Entire tail from base to tip must be continuously visible in both subjects with no parallax-induced foreshortening.

Manual:
Experimental Procedure
1. Display two live eastern gray squirrels (Sciurus carolinensis) from North American forest population in fixed frontal view.
2. Position female on left, male on right — strictly side-by-side, same background, same lighting.
3. Ensure full visibility of head, body, and tail for both; no occlusion.
Observation of Experimental Phenomena
Left squirrel (female): tail appears compact, less fluffy, visually shorter relative to body length.
Right squirrel (male): tail appears fluffier, more voluminous, visually longer relative to body length.
Summary of Experimental Principles
This demonstration illustrates a commonly cited, but not rigorously validated, visual impression: male eastern gray squirrels are often described as having fluffier, longer-looking tails, while females are often described as having more compact, shorter-looking tails. This is not an established sexual dimorphism in the species — sex in eastern gray squirrels is actually determined by anogenital inspection rather than tail appearance — so the comparison shown here should be understood as an illustrative visual impression rather than a validated biological sexing method.

Prompt Grounding rubric:
level_1: No gray squirrels present; or only one squirrel shown; or squirrels not labeled/positioned as left/right; or non-gray squirrel species (e.g., fox, red, black morphs) shown; or no side-by-side spatial arrangement.
level_2: Two squirrels present but incorrect positioning: both on same side, overlapped, or vertically stacked; or one squirrel is correctly positioned but the other is absent, cropped, or occluded; or at least one squirrel is misidentified by sex in labeling (e.g., female label on male-tail morphology or vice versa) without visual basis.
level_3: Two gray squirrels shown side-by-side in fixed viewpoint: left column contains a squirrel labeled or contextually indicated as female, right column contains a squirrel labeled or contextually indicated as male; tail region fully visible in both; no structural occlusion of tails; no species violation.
level_4: All conditions for score 3 met, AND both squirrels are from North American forest population (visually confirmed by typical pelage: grizzled gray dorsum, white-tipped tail hairs, pale ventrum); AND tail length relative to body is visibly distinguishable per sex (i.e., left tail appears compact/shorter, right tail appears fluffier/longer); no ambiguity in relative proportion impression.
level_5: All conditions for score 4 met, AND no visual artifact compromises identification: zero motion blur obscuring tail structure, zero lighting gradient that flattens fluffiness/compactness perception, zero perspective distortion altering tail-to-body proportion judgment, zero chromatic aberration affecting fur texture fidelity.

Scientific and Causal Correctness rubric:
level_1: Tail morphology contradicts knowledge point: e.g., left (female) squirrel shows fluffier/longer tail than right (male), or both tails are identical in fluffiness and relative length, or tails are artificially altered (e.g., prosthetic, animated exaggeration, non-biological shape).
level_2: One squirrel displays correct tail morphology but the other violates the expected tail-appearance contrast: e.g., female has fluffy/long tail OR male has compact/short tail; or tail length vs. body is misaligned with sex assignment (e.g., labeled male but tail clearly shorter than half body length); or fluffiness contrast is inverted or absent.
level_3: Left squirrel exhibits compact tail morphology (visibly less fluffy, visually shorter relative to body), right squirrel exhibits fluffy tail morphology (visibly denser fur, visually longer relative to body); both consistent with the commonly cited, illustrative-only tail-appearance impression for eastern gray squirrels (not presented as a validated sexing method); no internal contradiction in morphology-per-sex assignment.
level_4: All conditions for score 3 met, AND tail fur texture differentials are visually discriminable: left tail shows smooth/aligned hair strands with minimal volume; right tail shows splayed, voluminous, multi-directional hair strands creating perceptible fluff; AND tail base-to-tip contour supports length impression (left: tapered/shorter silhouette; right: full/extended silhouette).
level_5: All conditions for score 4 met, AND no perceptual ambiguity in causal attribution: fluffiness and length differences arise solely from natural fur structure and posture (no wind, no artificial fluffing, no grooming motion), and both squirrels maintain neutral, static quadrupedal pose, confirming morphology, not behavior, drives the contrast.

Spatiotemporal Consistency rubric:
level_1: Severe spatiotemporal rupture: e.g., squirrels teleport between frames; tail vanishes/reappears discontinuously; sudden scale jump; lighting shifts abruptly (e.g., daylight → dusk in <1s); background flickers or warps; structural break (e.g., tail detaches, body segments misalign).
level_2: Moderate inconsistency: e.g., one squirrel blinks while other remains static with open eyes; tail orientation changes without plausible cause (e.g., rotates 90° without head/body movement); shadow direction flips mid-sequence; partial occlusion appears/disappears without motion; background elements shift laterally without parallax.
level_3: Both squirrels remain fully visible throughout; no teleportation, no structural disintegration, no abrupt lighting/color shift, no frame-level tearing or stutter; tail regions maintain continuous visibility and stable spatial relationship (left/right columns preserved); background remains static and coherent.
level_4: All conditions for score 3 met, AND motion (if any) is biologically plausible and synchronous: e.g., subtle breathing motion occurs in both squirrels at same rhythm; ear twitches or eye blinks occur independently but never violate temporal plausibility (no >1s blink, no frozen gaze mismatch); no differential motion blur between left/right subjects.
level_5: All conditions for score 4 met, AND zero inter-frame jitter, zero depth-plane instability (no floating or sinking effect), zero edge aliasing on tail fur boundaries, zero perspective drift (camera remains orthographic/frontal fixed view), zero temporal desynchronization between left/right subject micro-motions.