It’s Not RoPE that Creates Sinks: The Role of Self-Concentration and Value-Non-Mixing in Attention

Raito Kiya, Satoki Ohashi, Kosuke Sato, Go Kamoda, Ryosuke Takahashi, Yuji Yamamoto, Daiki Shiono, Keisuke Sakaguchi, Goro Kobayashi


Abstract
Large Language Models (LLMs) often exhibit "Attention Sink" (AS) and the accompanying "Massive Activations" (MAs) at the initial position of a sequence. These phenomena frequently co-occur, and MAs can pose challenges for low-bit quantization. In this study, we analyze the factors underlying AS and MAs that emerge at the initial position regardless of the token occupying it. Our experiments suggest that self-concentration of attention, resulting from the causal mask, and the subsequent Value-non-mixing in attention outputs contribute to AS and MAs. These findings provide new empirical evidence on the internal dynamics of LLMs, offering insights that may inform future quantization strategies and advance our understanding of the internal mechanisms of attention layers.
Anthology ID:
2026.emnlp-main.1366
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
31160–31184
Language:
URL:
https://aclanthology.org/2026.emnlp-main.1366/
DOI:
Bibkey:
Cite (ACL):
Raito Kiya, Satoki Ohashi, Kosuke Sato, Go Kamoda, Ryosuke Takahashi, Yuji Yamamoto, Daiki Shiono, Keisuke Sakaguchi, and Goro Kobayashi. 2026. It’s Not RoPE that Creates Sinks: The Role of Self-Concentration and Value-Non-Mixing in Attention. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 31160–31184, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
It’s Not RoPE that Creates Sinks: The Role of Self-Concentration and Value-Non-Mixing in Attention (Kiya et al., EMNLP 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.emnlp-main.1366.pdf