arXiv Computation and Language
Aug 31

Tracing the complexity profiles of different linguistic phenomena through the intrinsic dimension of LLM representations

The paper investigates the intrinsic dimension (ID) of large language model (LLM) representations as an indicator of linguistic complexity. By comparing ID across model layers for coordination vs. subordination, right‑branching vs. center‑embedding, and unambiguous vs. ambiguous attachment, the authors find consistent ID differences that align with established complexity contrasts. Experiments across six LLMs, including representational similarity and layer pruning analyses, confirm that more complex phenomena produce higher ID profiles, with peaks occurring at different layers for each contrast.

By Marco Baroni, Emily Cheng, Iria de-Dios-Flores, Francesca Franzon