Domain: Healthcare — Human Physiology
Target concept: Touching a hot object causes the hand to withdraw rapidly.

Video generation prompt: A person touched a high-temperature metal surface, and the subsequent physiological responses were observed.

Evaluation guide:
(i) Target concept: Spinal nociceptive reflex to acute thermal stimulus.
Minimum mechanism: Intact peripheral sensory nerves (Aδ/C fibers), functional dorsal root ganglion, synapse in spinal cord gray matter, intact ventral horn motor neurons, and neuromuscular junctions, enabling automatic, rapid, stereotyped withdrawal without cortical involvement.
(ii)Storyline: [Phase 1: Baseline] Person stands still, hand suspended near but not touching metal surface; surface is static, well-lit, clearly metallic. [Phase 2: Stimulus Application] Hand moves linearly into contact; contact point is unambiguous and sustained for ≥1 visible motion unit. [Phase 3: Reflex Execution] Within same continuous motion flow, hand initiates rapid retraction directly away from surface, accelerating visibly; no voluntary action (e.g., turning head, speaking) interrupts sequence. [Phase 4: Completion] Hand clears proximity of surface; motion ends with natural deceleration, no secondary behavior. Perspective: Fixed frontal or slightly oblique angle, full hand and surface in frame, no occlusion of contact zone or withdrawal path.

Manual:
Experimental Procedure
1. A person extends hand toward a stationary, rigid, metallic surface (e.g., stainless steel plate).
2. Hand makes direct contact with surface.
3. Immediately upon contact, hand withdraws rapidly away from surface.
Observation of Experimental Phenomena
- Hand remains still before contact.
- Contact occurs with full palm or fingertips.
- Withdrawal begins within one visible motion segment after contact onset.
- Motion is direct, fast, and directed away from surface — no hesitation or redirection.
Summary of Experimental Principles
Touching a hot object causes the hand to withdraw rapidly — a spinal reflex arc bypassing conscious processing, mediated by sensory neurons, interneurons, and motor neurons.

Prompt Grounding rubric:
level_1: No person and metal surface both present is missing, or no hand-to-surface contact occurs, or no withdrawal motion follows contact; the scene does not show a hand touching a hot-looking metal surface at all.
level_2: A person and a metal surface (e.g., a stovetop, pan, or heated plate) both appear, but either the hand never makes contact with the surface, or contact happens and the hand simply stays in place with no retraction, or a retraction-like motion appears without any prior visible contact.
level_3: The hand is shown touching the metal surface and then pulling back; both the contact moment and the withdrawal are visible in the clip; the surface reads as metal (silvery or brushed finish, rigid edges, no liquid or fabric texture); the hand and forearm are anatomically normal and properly attached to the arm.
level_4: All of score 3, AND the hand stays in contact with the surface for a brief but visible moment before withdrawing (contact and withdrawal are not fused into a single instantaneous blur); AND the metal surface stays in the same place in the frame throughout; AND the person's torso and shoulder are oriented toward the surface during the whole action.
level_5: All of score 4, AND the hand travels toward the surface along a natural, continuous path (no jump-cut or warped approach), touches it with the palm or fingertips fully resolved (not blurred into the surface or ghosted), and withdraws completely clear of the surface in one continuous motion with no freeze-frame or jump; AND no unrelated object or action distracts from the touch-and-withdraw sequence.

Scientific and Causal Correctness rubric:
level_1: No withdrawal reflex is shown: the hand stays resting on or near the metal surface after contact, or it pulls back before ever touching the surface, or the retraction looks mechanical (a slow robotic-style lift, or the hand floating up) rather than a startled muscular pull.
level_2: The hand withdraws after contact, but the movement does not read as a fast protective reflex, e.g., it is slow and unhurried, pauses partway through, changes direction more than once, or only starts after an unrelated action such as the person glancing down or speaking first.
level_3: The hand withdraws quickly, beginning its retraction within the same continuous motion as the contact with no visible pause between touch and pull-back, and the retraction path leads straight away from the point of contact rather than sideways or downward.
level_4: All of score 3, AND the retraction is driven by movement of the forearm and hand rather than only a shoulder shrug or a whole-body flinch; AND no voluntary secondary behavior (shaking the hand, blowing on it, crying out) appears during the withdrawal itself, since a spinal reflex precedes any such conscious reaction.
level_5: All of score 4, AND the hand clears the surface in one smooth motion that accelerates away from contact and then naturally decelerates, with no stutter-step, mid-retraction pause, or reversal back toward the surface; AND the entire contact-to-withdrawal sequence reads as a single uninterrupted involuntary action with no competing visual or spoken cue suggesting a voluntary response instead.

Spatiotemporal Consistency rubric:
level_1: Severe break in continuity: the hand appears to jump into or out of the frame instead of moving there, the metal surface changes position or angle between the contact and withdrawal moments, the room lighting switches abruptly (e.g., a bright kitchen turning dark), the hand's shadow disappears or reappears in a different spot, or the hand/surface visibly distorts or fragments.
level_2: Noticeable but less severe break: the hand or surface flickers or stutters between frames, the contact and withdrawal are shown from two clearly different camera angles (e.g., front-on for contact, overhead for withdrawal) instead of one continuous shot, the shadow points in a direction inconsistent with the visible light source, or the hand's path shows a visible jump or warp partway through.
level_3: Small but visible inconsistencies remain: minor jitter in the hand's position while it is in contact with the surface, a slight mismatch in the shadow's length or angle from one moment to the next, or a brief moment where the hand and surface appear to gap and then touch again; no full teleportation or structural break occurs.
level_4: The hand and metal surface keep a stable spatial relationship throughout the approach; the point of contact stays in the same place in the frame; shadows and reflections on the surface change smoothly and stay physically consistent with a single light source; there are no visible cuts, flashes, or sudden perspective changes.
level_5: All of score 4, AND the motion from approach through contact to full withdrawal plays out as one continuous take: no duplicated or ghosted hand images, no motion blur that looks faster or slower than the actual movement, no gap in time between contact ending and withdrawal beginning, and the camera holds a single fixed viewpoint with no pan, tilt, zoom, or focus change during the entire sequence.