Not All Language Model Features Are One-Dimensionally Linear
Not on the map. Why?
Abstract (arXiv)
Recent work has proposed that language models perform computation by manipulating one-dimensional representations of concepts ("features") in activation space. In contrast, we explore whether some language model representations may be inherently multi-dimensional. We begin by developing a rigorous definition of irreducible multi-dimensional features based on whether they can be decomposed into either independent or non-co-occurring lower-dimensional features. Motivated by these definitions, we design a scalable method that uses sparse autoencoders to automatically find multi-dimensional features in GPT-2 and Mistral 7B. These auto-discovered features include strikingly interpretable examples, e.g. circular features representing days of the week and months of the year. We identify tasks where these exact circles are used to solve computational problems involving modular arithmetic in days of the week and months of the year. Next, we provide evidence that these circular features are indeed the fundamental unit of computation in these tasks with intervention experiments on Mistral 7B and Llama 3 8B, and we examine the continuity of the days of the week feature in Mistral 7B. Overall, our work argues that understanding multi-dimensional features is necessary to mechanistically decompose some model behaviors.
Key facts. Cited by 201 papers in the map (data through 7 Oct 2026). Builds on 31 of its 57 references that are in the map. First posted on arXiv 23 May 2024.
Builds on
31 of 57 references.
References · 31
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- 2024Opening the AI black box: program synthesis via mechanistic interpretabilitycited by 19
- 2024Monotonic Representation of Numeric Properties in Language Modelscited by 15
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Citing papers per year: 2024: 21; 2025: 61; 2026: 119.
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- 2026Causal and Interpretable Structures in LLM Compositional Tasks28 Sep 2026
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- 2026Interference Beyond Geometry in Concept Extraction28 Sep 2026
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