@inproceedings{jha-etal-2026-prism,
title = "{PRISM}: Prompt Representation Internalization via Selective Compression into {L}o{RA} Weights",
author = "Jha, Eshita and
Wang, Mingxian and
Barbu, Andrei and
Aggarwal, Chetan",
editor = "Lee, Hung-Yi and
Dev, Sunipa and
Li, Jessy and
Elliott, Desmond",
booktitle = "Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing",
month = oct,
year = "2026",
address = "Budapest, Hungary",
publisher = "Association for Computational Linguistics",
url = "https://aclanthology.org/2026.emnlp-main.2431/",
pages = "55189--55201",
ISBN = "979-8-89176-459-0",
abstract = "Deploying large language models for specialized tasks requires lengthy prompts combining schema, demonstrations, and instructions {---} creating a fundamental tension between prompt richness and inference feasibility. We identify and characterize two distinct prompt regimes: pattern-dominant tasks, where demonstrations drive performance through implicit formatting and extraction conventions, and procedure-dominant tasks, where explicit instructions carry the critical signal. To surface this distinction, we design a two-inference diagnostic that compares model performance with instructions alone versus examples alone, revealing which component to target for compression. Guided by this diagnostic, we introduce PRISM, a self-distillation framework that generates silver training data from the model{'}s own full-prompt outputs and trains lightweight LoRA adapters to internalize the dominant component{'}s behavior. PRISM recovers 131{\%} of example benefit on CUAD and 151{\%} on MultiWOZ (pattern-dominant), and 39{\%} of instruction benefit on GSM8K (procedure-dominant), eliminating 72{--}79{\%} of prompt tokens at inference time. Silver data captures 80{--}94{\%} of gold-labeled performance without human annotations. Beyond compression, PRISM frees context capacity: replacing a long prompt with LoRA weights enables 89.5{\%} compliance with new runtime instructions versus 75.4{\%} with recency prompting. The diagnostic suggests a practical pre-training heuristic to indicate when distillation is likely to succeed, helping practitioners avoid costly training on non-beneficial components."
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<abstract>Deploying large language models for specialized tasks requires lengthy prompts combining schema, demonstrations, and instructions — creating a fundamental tension between prompt richness and inference feasibility. We identify and characterize two distinct prompt regimes: pattern-dominant tasks, where demonstrations drive performance through implicit formatting and extraction conventions, and procedure-dominant tasks, where explicit instructions carry the critical signal. To surface this distinction, we design a two-inference diagnostic that compares model performance with instructions alone versus examples alone, revealing which component to target for compression. Guided by this diagnostic, we introduce PRISM, a self-distillation framework that generates silver training data from the model’s own full-prompt outputs and trains lightweight LoRA adapters to internalize the dominant component’s behavior. PRISM recovers 131% of example benefit on CUAD and 151% on MultiWOZ (pattern-dominant), and 39% of instruction benefit on GSM8K (procedure-dominant), eliminating 72–79% of prompt tokens at inference time. Silver data captures 80–94% of gold-labeled performance without human annotations. Beyond compression, PRISM frees context capacity: replacing a long prompt with LoRA weights enables 89.5% compliance with new runtime instructions versus 75.4% with recency prompting. The diagnostic suggests a practical pre-training heuristic to indicate when distillation is likely to succeed, helping practitioners avoid costly training on non-beneficial components.</abstract>
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%0 Conference Proceedings
%T PRISM: Prompt Representation Internalization via Selective Compression into LoRA Weights
%A Jha, Eshita
%A Wang, Mingxian
%A Barbu, Andrei
%A Aggarwal, Chetan
%Y Lee, Hung-Yi
%Y Dev, Sunipa
%Y Li, Jessy
%Y Elliott, Desmond
%S Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
%D 2026
%8 October
%I Association for Computational Linguistics
%C Budapest, Hungary
%@ 979-8-89176-459-0
%F jha-etal-2026-prism
%X Deploying large language models for specialized tasks requires lengthy prompts combining schema, demonstrations, and instructions — creating a fundamental tension between prompt richness and inference feasibility. We identify and characterize two distinct prompt regimes: pattern-dominant tasks, where demonstrations drive performance through implicit formatting and extraction conventions, and procedure-dominant tasks, where explicit instructions carry the critical signal. To surface this distinction, we design a two-inference diagnostic that compares model performance with instructions alone versus examples alone, revealing which component to target for compression. Guided by this diagnostic, we introduce PRISM, a self-distillation framework that generates silver training data from the model’s own full-prompt outputs and trains lightweight LoRA adapters to internalize the dominant component’s behavior. PRISM recovers 131% of example benefit on CUAD and 151% on MultiWOZ (pattern-dominant), and 39% of instruction benefit on GSM8K (procedure-dominant), eliminating 72–79% of prompt tokens at inference time. Silver data captures 80–94% of gold-labeled performance without human annotations. Beyond compression, PRISM frees context capacity: replacing a long prompt with LoRA weights enables 89.5% compliance with new runtime instructions versus 75.4% with recency prompting. The diagnostic suggests a practical pre-training heuristic to indicate when distillation is likely to succeed, helping practitioners avoid costly training on non-beneficial components.
%U https://aclanthology.org/2026.emnlp-main.2431/
%P 55189-55201
Markdown (Informal)
[PRISM: Prompt Representation Internalization via Selective Compression into LoRA Weights](https://aclanthology.org/2026.emnlp-main.2431/) (Jha et al., EMNLP 2026)
ACL