Aaron Mueller

@amuuueller.bsky.social

Postdoc at Northeastern and incoming Asst. Prof. at Boston U. Working on NLP, interpretability, causality. Previously: JHU, Meta, AWS

If you'll be at ACL or ICML this year, come check out the work from our group and collaborators - summary 🧵 below. Lots to like for those into {mechanistic, developmental, pragmatic} interpretability! I'll be at ACL; say hi!

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The New England Mechanistic Interpretability (NEMI) workshop is coming to BU on Aug. 14! Join us for talks, a panel, food, and plenty of opportunities to connect with the many great researchers in the area. Register and help spread the word!

Micah Benson@micahben.bsky.social · 2mo ago

🧠🤖 The 2026 New England Mechanistic Interpretability (NEMI) Workshop will be Aug. 14 at Boston University! Help spread the word and join the New England mech interp community! Registration and submission info in thread:👇

BU campus and Boston skyline

I truly believe the rapid advances in the mech interp subfield have something real to offer AI ethics researchers: A chance to look beyond the HOW of evals to the WHY, a first pass at a technical solution when we see the opportunity, a new avenue for showing failures that prove models are not gods

Representation steering is now a common way to mitigate LLM shortcuts. How much legitimate knowledge does this tend to remove? Turns out that these methods can be surprisingly precise! But also: no single steering operation will fix all shortcuts. Led by @shanzzyy.bsky.social!

Zhengyang Shan@shanzzyy.bsky.social · 7mo ago

Can steering remove LLM shortcuts without breaking legitimate LLM capabilities? In our @eaclmeeting.bsky.social paper, we show that conceptual bias is separable from concept detection; this means inference-time debiasing is possible with minimal capability loss.

What's the right unit of analysis for understanding LLM internals? We explore in our mech interp survey (a major update from our 2024 ms). We’ve added more recent work and more immediately actionable directions for future work. Now published in Computational Linguistics!

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In neuroscience, we often try to understand systems by analyzing their representations — using tools like regression or RSA. But are these analyses biased towards discovering a subset of what a system represents? If you're interested in this question, check out our new commentary! Thread:

What do representations tell us about a system? Image of a mouse with a scope showing a vector of activity patterns, and a neural network with a vector of unit activity patterns
Common analyses of neural representations: Encoding models (relating activity to task features) drawing of an arrow from a trace saying [on_____on____] to a neuron and spike train. Comparing models via neural predictivity: comparing two neural networks by their R^2 to mouse brain activity. RSA: assessing brain-brain or model-brain correspondence using representational dissimilarity matrices
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Tried steering with SAEs and found that not all features behave as expected? Check out our new preprint - "SAEs Are Good for Steering - If You Select the Right Features" 🧵

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Lots of progress in mech interp (MI) lately! But how can we measure when new mech interp methods yield real improvements over prior work? We propose 😎 𝗠𝗜𝗕: a 𝗠echanistic 𝗜nterpretability 𝗕enchmark!

Logo for MIB: A Mechanistic Interpretability Benchmark

It’s common to assume one task = one static circuit. But this ignores that the important computations depend on position! We propose a way to find 𝗽𝗼𝘀𝗶𝘁𝗶𝗼𝗻-𝗮𝘄𝗮𝗿𝗲 circuits. (Highlight: using LLMs to help us create multi-token causal abstractions!)

Tal Haklay@talhaklay.bsky.social · last yr.

1/13 LLM circuits tell us where the computation happens inside the model—but the computation varies by token position, a key detail often ignored! We propose a method to automatically find position-aware circuits, improving faithfulness while keeping circuits compact. 🧵👇

What can mechanistic interpretability do for computational psycholinguists? @michaelwhanna.bsky.social and I took a stab at this question! We investigate garden path sentence processing in LMs at the feature (circuit) level.

Michael Hanna@michaelwhanna.bsky.social · 2y ago

Sentences are partially understood before they're fully read. How do LMs incrementally interpret their inputs? In a new paper, @amuuueller.bsky.social and I use mech interp tools to study how LMs process structurally ambiguous sentences. We show LMs rely on both syntactic & spurious features! 1/10