STAGE: Diagnosing Semantic Transfer at Grounded Execution in Embodied Agents

Baosheng Jin, Yushen Liang, Hua Shen


Abstract
Embodied language grounding requires more than identifying the referent of an instruction: recovered semantics must also control the action an agent exposes. We study this missing link as a semantic–action gap, where instruction semantics are recoverable but weakly expressed in native continuous actions. We introduce SAT-Bench, a fixed-observation counterfactual benchmark that holds the visual scene and agent state fixed while changing only instruction semantics. On LIBERO target-name and pixel-grounded relation swaps, target recovery reaches 100.0% and 95.8%, whereas OpenVLA action sensitivity remains only 6.8% and 7.7%. The gap persists across 1,000 additional compositional and temporal/procedural counterfactuals, with overall action sensitivity of 6.1%. Hidden-state, threshold-free, cross-policy, and rollout diagnostics further support this semantic–action transfer failure. We introduce VISA, a lightweight execution-time interface that converts recovered semantics into ALLOW, DEFER, target-consistency, and verified-selection decisions. VISA reduces invalid-instruction blind execution from 92.7% to 2.8% while preserving 94.0% of normal commands, and verified selection further improves target-consistent action exposure without updating the underlying policy. Overall, embodied language evaluation should measure semantic–action transfer, not semantic parsing alone.
Anthology ID:
2026.findings-emnlp.1148
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
24309–24331
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.1148/
DOI:
10.18653/2026.findings-emnlp.1148
Bibkey:
Cite (ACL):
Baosheng Jin, Yushen Liang, and Hua Shen. 2026. STAGE: Diagnosing Semantic Transfer at Grounded Execution in Embodied Agents. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 24309–24331, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
STAGE: Diagnosing Semantic Transfer at Grounded Execution in Embodied Agents (Jin et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.1148.pdf