Modulating Multi-Label Tendency in Zero-Shot LLM Coding: The Effect of Output Structure on CDSS Feedback Analysis

Hyunwoo Choo, Sungsoo Hong


Abstract
Large language models (LLMs) often default to single-label classification in zero-shot multi-label tasks—a tendency we term "conservative default". While few-shot prompting mitigates this, it introduces "example bias". We evaluate zero-shot strategies to modulate this tendency using 1,441 healthcare feedback records and two LLMs. We compare instruction-based methods with structural constraints that modify the token generation sequence, specifically an Enum-First format requiring domain enumeration before selection. Results show that structural constraints substantially reduce single-label rates (Magistral: 96% → 19%; Qwen3: 54% → 0.0%), though the latter suggests potential over-correction compared to human baselines (16.7–41.3%). These findings indicate that while output structure is a potent modulator of classification behavior by shifting the decision point upstream, its effect magnitude is model-dependent, necessitating empirical calibration to prevent spurious associations.
Anthology ID:
2026.healing-1.14
Volume:
Proceedings of the 1st Workshop on Linguistic Analysis for Health (HeaLing 2026)
Month:
March
Year:
2026
Address:
Rabat, Morocco
Editors:
Vera Danilova, Murathan Kurfalı, Ylva Söderfeldt, Julia Reed, Andrew Burchell
Venues:
HeaLing | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
172–179
Language:
URL:
https://preview.aclanthology.org/ingest-eacl/2026.healing-1.14/
DOI:
Bibkey:
Cite (ACL):
Hyunwoo Choo and Sungsoo Hong. 2026. Modulating Multi-Label Tendency in Zero-Shot LLM Coding: The Effect of Output Structure on CDSS Feedback Analysis. In Proceedings of the 1st Workshop on Linguistic Analysis for Health (HeaLing 2026), pages 172–179, Rabat, Morocco. Association for Computational Linguistics.
Cite (Informal):
Modulating Multi-Label Tendency in Zero-Shot LLM Coding: The Effect of Output Structure on CDSS Feedback Analysis (Choo & Hong, HeaLing 2026)
Copy Citation:
PDF:
https://preview.aclanthology.org/ingest-eacl/2026.healing-1.14.pdf