Beyond Diagnosis: Evaluating Recommendation Stability under Counterfactual Skin-Tone Perturbations

Hyunwoo Yoo, Kyusik Kim, Gail Rosen


Abstract
Multimodal clinical models have shown strong performance in dermatology recommendation and triage tasks, yet their robustness under demographic perturbations remains poorly understood. We introduce a clinician-validated counterfactual dermatology benchmark for evaluating recommendation stability under skin-tone perturbations in multimodal vision-language models. Our benchmark contains 240 physician-validated images from 60 clinical cases, each paired with four diagnosis- and severity-matched skin-tone variants constructed through iterative LLM filtering and physician review. Across diagnosis, management, urgency, and referral tasks, we observe substantial model-dependent instability even when clinicians verified preservation of diagnosis and severity across perturbation variants. Recommendation changes occur in up to 51.7% of paired comparisons, accompanied by shifts in uncertainty framing, pigmentation-sensitive terminology, and escalation-oriented language. Our findings suggest that demographic perturbations can influence not only diagnostic predictions, but also downstream recommendation behavior in multimodal clinical models. We release a controlled evaluation framework for studying recommendation robustness in medical AI systems.
Anthology ID:
2026.findings-aacl.230
Volume:
Findings of the Association for Computational Linguistics: IJCNLP-AACL 2026
Month:
November
Year:
2026
Address:
Hengqin, China
Editors:
Yue Zhang, Ruifeng Xu, Ayu Purwarianti, Tong Rong, Jun Suzuki
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
4549–4564
Language:
URL:
https://aclanthology.org/2026.findings-aacl.230/
DOI:
Bibkey:
Cite (ACL):
Hyunwoo Yoo, Kyusik Kim, and Gail Rosen. 2026. Beyond Diagnosis: Evaluating Recommendation Stability under Counterfactual Skin-Tone Perturbations. In Findings of the Association for Computational Linguistics: IJCNLP-AACL 2026, pages 4549–4564, Hengqin, China. Association for Computational Linguistics.
Cite (Informal):
Beyond Diagnosis: Evaluating Recommendation Stability under Counterfactual Skin-Tone Perturbations (Yoo et al., Findings 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.findings-aacl.230.pdf