Influcoder: Distilling Decoders’ Gradient Influence Rankings into an Encoder for Data Attribution

Dimitri Kachler, Damien Sileo, Pascal Denis


Abstract
Data attribution traces model behavior back to individual training examples, with applications such as identifying training data that induces toxic responses or tracing a model’s factual claims back to the examples that support them. Gradient-based influence methods provide reliable attribution performance, yet are impractical at the scale of LLM training datasets due to their high computational costs. We introduce Influcoder, which distills the LoRA-gradient cosine influence rankings of a target decoder into a compact encoder, reducing attribution at inference time to an embedding cosine similarity. It scores training examples 35x faster than gradient-based influence computed on the target model and 18x faster than influence computed on the smallest comparable proxy model. Our method remains competitive with gradient-based methods even when considering the setup cost, as evaluated on two downstream tasks of toxicity filtering and factual attribution.
Anthology ID:
2026.aacl-short.49
Volume:
Proceedings of the 15th International Joint Conference on Natural Language Processing and the 5th Conference of the Asia-Pacific Chapter of the Association for Computational Linguistics (Volume 2: Short Papers)
Month:
November
Year:
2026
Address:
Hengqin, China
Editors:
Yue Zhang, Ruifeng Xu, Ayu Purwarianti, Tong Rong, Jun Suzuki
Venues:
AACL | IJCNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
780–788
Language:
URL:
https://aclanthology.org/2026.aacl-short.49/
DOI:
Bibkey:
Cite (ACL):
Dimitri Kachler, Damien Sileo, and Pascal Denis. 2026. Influcoder: Distilling Decoders’ Gradient Influence Rankings into an Encoder for Data Attribution. In Proceedings of the 15th International Joint Conference on Natural Language Processing and the 5th Conference of the Asia-Pacific Chapter of the Association for Computational Linguistics (Volume 2: Short Papers), pages 780–788, Hengqin, China. Association for Computational Linguistics.
Cite (Informal):
Influcoder: Distilling Decoders’ Gradient Influence Rankings into an Encoder for Data Attribution (Kachler et al., AACL-IJCNLP 2026)
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PDF:
https://aclanthology.org/2026.aacl-short.49.pdf