Domain: Humanities and Social Sciences — Linguistics
Target concept: Sagittal MRI view of the oral cavity, showing tongue movement during different vowel articulations

Video generation prompt: A sagittal MRI view of the human oral cavity, illustrating a speaker producing the vowels [i e a o u] alternately, showing the variation of tongue position during articulation within a fixed lateral section.

Evaluation guide:
(i) Target concept: Real-time sagittal MRI visualization of vowel-specific tongue dorsum positioning in a fixed anatomical plane.
Minimum mechanism: Subject must be capable of sustained, controlled vowel articulation; MRI acquisition must maintain geometric stability of the midsagittal slice; tongue musculature must respond to phonemic instruction with biomechanically constrained displacement.
(ii)Storyline: Frame 0–1: Baseline tongue position (neutral or resting); Frame 1–2: [i] onset → tongue dorsum rises and advances sharply; Frame 2–3: [e] onset → tongue lowers slightly and retracts; Frame 3–4: [a] onset → tongue lowers maximally and retracts further; Frame 4–5: [o] onset → tongue rises and retracts more; Frame 5–6: [u] onset → tongue rises to highest point and retracts fully; all transitions occur within same fixed lateral MRI section; no head motion; tongue contour remains anatomically coherent and continuous throughout.

Manual:
Experimental Procedure
1. Position subject supine in MRI scanner; acquire real-time sagittal midline MRI slice through oral cavity.
2. Instruct speaker to produce vowels [i], [e], [a], [o], [u] in strict sequence, one per ~2 seconds, maintaining steady head position.
3. Record continuous 10-second cine-MRI video showing tongue movement across the fixed lateral section.
Observation of Experimental Phenomena
Tongue position changes visibly across five stages: [i] -- highest and most anterior; [e] -- mid-high, less anterior than [i]; [a] -- lowest of the five and central, clearly less retracted than [o] or [u]; [o] -- mid-high and posterior, further back than [a]; [u] -- highest and most posterior, the most retracted of the five. All five positions are mutually distinguishable within the same sagittal plane.
Summary of Experimental Principles
Sagittal MRI captures dynamic articulatory phonetics: vowel production correlates with systematic tongue dorsum height (high/mid/low) and advancement (front/central/back), observable as visually distinct tongue configurations in a fixed midsagittal plane.

Prompt Grounding rubric:
level_1: No sagittal MRI view of the oral cavity is shown; or no human tongue is visible; or no sequence of vowel productions is depicted at all; or the shot is not framed as a fixed lateral (side) section of the head.
level_2: A sagittal MRI view is present, but the orientation is wrong (e.g., an axial or coronal slice instead of a side view); or the tongue is visible but stays static the whole time; or at least one vowel label ([i], [e], [a], [o], or [u]) appears on-screen with no corresponding tongue movement; or the viewpoint shifts, rotates, or zooms during the clip.
level_3: The sagittal MRI view is present and correctly oriented as a side view of the head; the tongue is visible and moves; the labels [i], [e], [a], [o], [u] all appear on-screen at some point; the same lateral section framing is kept throughout; however, the labels appear out of the correct [i]->[e]->[a]->[o]->[u] order, or one or more labels are missing or repeated.
level_4: The sagittal MRI view is present and correctly oriented; the tongue is visible and moves; the five vowel labels [i e a o u] appear in the correct sequential order; the same fixed lateral section framing is maintained throughout with no zoom, rotation, or shift; the tongue visibly changes shape or position during each of the five labeled segments (it is never static while a label is showing).
level_5: All conditions for score 4 satisfied, AND the tongue's motion between each pair of labeled vowels is smooth, with no jump-cut in tongue shape at any label change; the head and jaw stay still throughout so that only the tongue itself appears to move within the frame; the surrounding anatomical landmarks (palate, jaw, pharyngeal wall) stay visible in the same on-screen location across all five vowel segments.

Scientific and Causal Correctness rubric:
level_1: No correspondence exists between tongue position and vowel identity; all five tongue shapes look identical or vary with no discernible pattern; the labels do not causally track the tongue posture (e.g., the [i] label appears while the tongue sits low and back, the shape expected for [a] or [o]).
level_2: Vowel labels are present but appear out of canonical order; the tongue moves but without systematic directionality; at least three of the five vowels show identical tongue height and advancement; no consistent pattern links a given label to the tongue configuration shown under it.
level_3: Labels [i e a o u] appear in the correct order; the tongue moves with a directional progression consistent with going from a high-front position toward a low-central position and on to a high-back position; but two of the five vowels share indistinguishable tongue configurations (e.g., [e] and [o] both show a similar mid-height, mid-advancement shape); the label-to-posture correspondence holds only partially.
level_4: Labels [i e a o u] appear in the correct order; the tongue configuration changes systematically across the sequence; four of the five vowels show mutually distinguishable tongue positions; one vowel's configuration is ambiguous because of motion blur or occlusion but remains plausible given the surrounding context; the causal chain from label to expected articulation to observed tongue posture holds for all five vowels with only this one minor deviation.
level_5: Labels [i e a o u] appear in the correct order; each label coincides with a tongue configuration that is uniquely and unambiguously identifiable as the canonical articulatory posture for that vowel; no two vowels share overlapping height/advancement combinations; all five postures are biomechanically consistent with known vowel articulation (e.g., [i] and [u] are both high but differ in frontness versus backness, with [u] being the most retracted of the five; [a] is the lowest vowel and sits centrally, clearly less retracted than [o] or [u]); the causal chain from label to expected articulation to observed posture is fully intact and verifiable frame by frame.

Spatiotemporal Consistency rubric:
level_1: Severe spatiotemporal rupture: the tongue vanishes or reappears abruptly between frames; the MRI image flickers, freezes, or warps severely; the viewing angle suddenly jumps to a different plane mid-clip; frames freeze and then skip ahead; the MRI image brightness changes erratically from frame to frame as if the scan parameters reset.
level_2: Moderate discontinuity: the tongue's motion is jerky, with two or more visible frame drops; the MRI slice boundary shifts laterally or rotates more than 10 degrees; the tongue's outline fractures into disconnected segments for at least one frame; the MRI image's brightness or contrast flickers noticeably across three or more consecutive frames.
level_3: Only minor discontinuities appear: the tongue contour shows a brief stutter (1-2 frames of near-stillness within otherwise continuous motion); the MRI background (palate, jaw, pharyngeal wall) stays recognizable, with only the subtle brightness fluctuation typical of live MRI acquisition; no structural break appears in the tongue or oral cavity; the framing shows no perceptible drift across the video.
level_4: The tongue's motion is continuous and fluid, with no visible stutter, freeze, or jump; the MRI background stays stable in shape, contrast, and position, without the slice-brightness flicker that live cine-MRI can otherwise show; no structural break appears in the tongue or oral anatomy; one instance of mild blurring at the tongue tip during the fastest transition (e.g., moving into the [u] position) is acceptable as long as the tongue's overall shape and position stay identifiable.
level_5: The tongue's motion is smooth and continuous across the entire sequence; the MRI background remains visibly stable in geometry, contrast, and brightness throughout, with no perceptible slice-signal flicker; no motion blur obscures the tongue's boundary or its position relative to the palate and pharyngeal wall at any labeled vowel; no structural distortion, tearing, or warping appears anywhere in the clip; all anatomical contours stay sharp and consistent from the first frame to the last.