Claude reinvestigates herself: A replication of different types of syntactic agreement recruit the same units in LLMs

Elena Polyakova, Shivan Arora, Suchir Salhan, Paula Buttery


Abstract
The representation of grammatical knowledge in individual LLM neurons and attention heads remains poorly understood. We replicate the feature-based approach of Kryvosheieva et al. (2026) that uses functional localisation to illustrate that distinct syntactic phenomena can recruit the same units. We reproduce and extend the paper to new minimal pair datasets (Dutch, Turkish, and Russian) and additional interpretability techniques: Attention-based analysis, Differential Binary Masking (DBM), and Distributed Alignment Search (DAS). We find reproducible and robust evidence for syntactic localisation in LLMs across several methods and languages. However, localisation strength depends on interpretability techniques (particularly for DBM) and varies across languages, highlighting the value of validating mechanistic claims using several techniques. Code and data available via https://anonymous.4open.science/r/syntax-interpretability-F4C3
Anthology ID:
2026.blackboxnlp-1.69
Volume:
Proceedings of the 9th BlackboxNLP Workshop: Analyzing and Interpreting Neural Networks for NLP
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Dana Arad, Yonatan Belinkov, Hanjie Chen, Nils Feldhus, Aaron Mueller, Hosein Mohebbi, Gabriele Sarti, Martin Tutek
Venues:
BlackboxNLP | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
1196–1222
Language:
URL:
https://aclanthology.org/2026.blackboxnlp-1.69/
DOI:
Bibkey:
Cite (ACL):
Elena Polyakova, Shivan Arora, Suchir Salhan, and Paula Buttery. 2026. Claude reinvestigates herself: A replication of different types of syntactic agreement recruit the same units in LLMs. In Proceedings of the 9th BlackboxNLP Workshop: Analyzing and Interpreting Neural Networks for NLP, pages 1196–1222, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Claude reinvestigates herself: A replication of different types of syntactic agreement recruit the same units in LLMs (Polyakova et al., BlackboxNLP 2026)
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PDF:
https://aclanthology.org/2026.blackboxnlp-1.69.pdf