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Cammarata and Goodfire claim most neurons are readable; researchers disagree

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In mid-October 2026, Nick Cammarata and the Goodfire team published a long article arguing that most internal computation in neural networks follows regular patterns rather than being a chaotic jumble. Cammarata said that when he participated in OpenAI's mechanistic interpretability work in his early years and launched its first large-scale automated interpretability project, using primitive tools he found only about 2% of neurons readable, and he was therefore pessimistic for a time; with modern agent tools, he believes that in models up to the trillion-parameter scale, the vast majority of neurons are readable, that many famous "entangled neuron" cases are actually misunderstandings, and that early polysemanticity stems from several ordinary and mostly fixable problems rather than superposition. He reinterpreted a neuron in InceptionV1 that responds to both cat faces and car fronts as a V-shaped detector, and proposed "recursive generalization." A preliminary review of Qwen3-32B showed that about 90% of neurons have one main job at each of the positive and negative poles, about 7% have two, and 2% to 4% are unexplainable. The team also drew a circuit diagram using a trillion-parameter model answering "whether to return a found wallet" as an example, and tested the explanation by turning off neurons: after turning off 20 neurons labeled "Christmas," the model's probability of answering "Santa Claus" was still 76%, while switching to another 8 key neurons made it plummet to 6%. These claims sparked disagreement in the field: LessWrong user leogao wrote a rebuttal arguing that activation examples matching a pattern does not mean the neuron has been explained, and advocated instead using downstream KL and large-dataset simulation scores for testing; Dean Ball pointed out that the analysis mainly relies on Cammarata's subjective judgment, and that a technical paper is about to be published; Zvi considered this an important update, but still far from solving interpretability and alignment.

Generated by AI from reports · Updated 9 days ago

Latest developments

4 developments
  1. · 1 report
    Zvi reviews Goodfire's neuron interpretability breakthrough
    LessWrong: Zvi reviews Goodfire's new work on neuron interpretability: most neurons correspond to only one concept, but alignment is far from solved
  2. · 2 reports
    The author argues that neuron interpretability is not yet solved
    LessWrong: Neural networks are not yet clean
  3. · 1 report
    Dean Ball comments on interpretability breakthroughs and superposition theory
    Dean Ball: The Beauty of Things That Grow: Dean Ball on Interpretability and AI Policy
  4. · 7 reports
    Nick Cammarata says neural network interpretability has achieved a breakthrough
    Goodfire Research: Goodfire research says neural networks are already clean

Progress timeline

Oct 20
  1. MIT Technology Review
    "We were wrong before": Goodfire researcher says neural networks are more understandable than expected

    Goodfire researcher Nick Cammarata published a 26,000-word blog post arguing that the internal mechanisms of LLMs may be far more understandable than previously thought, and therefore easier to monitor and control, sparking widespread discussion in the AI world. He reexamined Google's 2014 image recognition model Inception v1, arguing that multi-task neurons previously interpreted as superposition actually encode common shapes, such as the V shape shared by cat faces and car fronts. He said the team has begun studying modern LLMs and will soon publish technical results. Chris Potts of Stanford considers this just intuition; Jacob Hilton of the Alignment Research Center said researchers' understanding of the internal mechanisms of top LLMs is less than 0.01%; Neel Nanda of Google DeepMind also believes this is not a significant advance for the big picture of interpretability. Cammarata acknowledged that outsiders overinterpreted his claims.

Oct 19
  1. LessWrongSelected
    Zvi reviews Goodfire's new work on neuron interpretability: most neurons correspond to only one concept, but alignment is far from solved

    LessWrong author Zvi lays out the polarized reactions to Goodfire researcher Nick Cammarata's article "Neural networks are already clean," arguing that it is an important update on neuron interpretability, but still far from solving interpretability and alignment. Cammarata says the cause of polysemanticity in early models is not superposition, but several ordinary and mostly fixable problems, plus what he calls "recursive generalization"; a preliminary audit of Qwen3-32B estimates that about 90% of neurons have only one primary function, about 7% have two related functions, and 2% to 4% are not yet understood, with similar results on trillion-parameter models such as Kimi K3. OpenAI researchers including Dean W. Ball and roon say its significance is comparable to "Attention Is All You Need," while Neel Nanda, Leo Gao, Joshua Achiam and Eliezer Yudkowsky argue that progress is limited and that the explanations themselves still need more rigorous evaluation.

  2. WebDon't Worry About the Vase· Media coverage
    I Can See Everything(opens the original post in a new tab)
Oct 18
  1. X @NeelNanda5
    @nabla_theta publishes new blog post "Neural networks are not already clean"

    @nabla_theta published a new blog post, "Neural networks are not already clean." @NeelNanda5 said this is another contribution to the discussion of "no, we haven't solved interpretability yet."

Oct 17
  1. LessWrong
    Neural networks are not yet clean

    LessWrong user leogao wrote a rebuttal to Nick Cammarata's judgment that neuron polysemanticity is overestimated, arguing that activation examples matching a pattern does not mean the neuron has been explained. Using a neuron associated with both dogs and bicycles as an example, the article points out that top activation examples may only correspond to some subset that is difficult to characterize compactly, and the reverse relationship does not necessarily hold. The author advocates instead using downstream KL and computing simulation scores on large datasets: if replacing the neuron with a simulated value significantly degrades model performance, the explanation does not hold, and this criterion can also flag bad explanations previously treated as polysemantic explanations. The author speculates that ablating weak activations would also significantly degrade model performance, so weak activations should not be completely ignored. The author also believes that explaining neurons is only part of understanding network computation; concepts are stored in a superimposed manner, making circuit research still unable to explain most of the variance in model behavior.

Oct 16
  1. Dean Ball
    The Beauty of Things That Grow: Dean Ball on Interpretability and AI Policy

    Dean Ball writes a commentary on former OpenAI researcher Nick Cammarata's new perspective on mechanistic interpretability. Cammarata argues that the previous view of neurons as human-like concepts was wrong; neurons are more like control flow, with meaning accumulating layer by layer during training, so models are more interpretable than previously thought. He revisits the classic cat-and-car neuron in a 2017 vision model, arguing it detects V-shaped objects, and calls this property recursive generalization. Ball notes that the analysis relies heavily on Cammarata's subjective judgment, the technical paper is forthcoming, and much uncertainty remains about understanding interactions among millions of neurons. Ball also speculates that if interpretability nears a solution, those focused on catastrophic alignment risk would be pleased, while those more concerned about power concentration and labor markets might see it as bad news.

  2. The Decoder
    Is AI interpretability close to a breakthrough? A new article divides researchers

    Mechanistic interpretability researcher Cammarata, in a new article, reinterprets classic findings such as polysemantic neurons and superposition, arguing that these most famous examples have been misread, sparking disagreement in the field. He reinterprets the neuron in InceptionV1 that responds to both cat faces and car fronts as a V-shape detector, treats the car hidden in the dog neuron in the paper Zoom In as ordinary generalization, and proposes a pattern of recursive generalization. He gives preliminary numbers for Qwen3-32B: about 90% of neuron poles have only one primary function, about 7% have two related functions, and 2% to 4% are unexplainable; Goodfire says it sees similar results on models with trillions of parameters. OpenAI employee Roon says this could be an important moment in the history of science, while Google DeepMind interpretability team lead Neel Nanda says it does not change the big picture and insists that superposition still exists. Cammarata believes interpretability is crucial to AI safety, otherwise it is hard to judge whether models are deceiving.

  3. WeChat · AI Era (Xinzhiyuan)
    Former OpenAI researcher Nick Cammarata and Goodfire: about 90% of neurons each have one primary task

    OpenAI 前研究员 Nick Cammarata 与 Goodfire 团队发布长文《神经网络早已「干净」》,提出神经网络的内部计算大多有规律可循,而非混乱的拼盘。团队以一个万亿参数模型回答「捡到钱包是否归还」为例画出电路图,追踪答案如何形成,再通过关闭神经元检验解释是否可靠:关掉 20 个标为「圣诞节」的神经元后,模型回答「圣诞老人」的概率仍有 76%,换成另外 8 个关键神经元则骤降到 6%。在一个 320 亿参数语言模型中,团队分开统计神经元的正负响应,粗略估计约 90% 各有一个主要任务,约 2% 至 4% 仍未理解;Nick 估计 ConvNeXt 视觉模型最后一层约 99% 的神经元可解释。团队还让一个 Agent 写神经元功能说明、另一个据此造句做盲测,183 个正向解释中目标例子强激活比例 76%、干扰例子 11%,逐个比较为 164 胜 15 平 4 负。

  4. WeChat · Synced (Jiqizhixin)Selected
    OpenAI interpretability team creator says large model black boxes are almost readable; about 90% of neurons in Qwen3-32B have a single function

    Nick Cammarata, creator of OpenAI's interpretability team, said in a long post that with modern agent tools, trillion-parameter large models are almost readable, and that the superposition hypothesis, which held that neural network representations are entangled, is a misunderstanding. Re-examining a neuron in InceptionV1 that responds to both cat faces and car fronts, he believes the two share a V-shaped feature, and that neurons are more like verbs that distinguish patterns than nouns that label objects. The author's preliminary review of Qwen3-32B shows that about 90% of neurons have one main job at each of the positive and negative poles, about 7% have two, and 2% to 4% are not yet understood; conclusions are similar for dense models and MoE models. The author says he produced the first known attribution map for a trillion-parameter model on Kimi K3, and when re-examining GPT-2 XL with new tools, about 70% of neurons are also roughly one thing. Agents are used to inspect neuron samples, propose explanations, trace upstream and downstream connections, and design counterexample experiments.

  5. Goodfire ResearchSelected
    Goodfire research says neural networks are already clean

    Goodfire Research proposes that the cause of polysemy in early model organisms is not superposition, but several ordinary and mostly fixable problems. The organization says it can now understand most neurons in models with up to trillions of parameters, and believes the prospects for mechanistic interpretability may be far more optimistic than previously expected.

  6. X @HaydnBelfield
    Nick Cammarata says modern agent tools make the vast majority of neurons in large models readable

    Researcher Nick Cammarata said that with modern agent tools and closer observation, the vast majority of neurons in models with parameter scales up to trillions are readable, circuit structures are clear, and many famous "entangled neuron" cases are actually misunderstandings. He was involved in OpenAI's mechanistic interpretability work in his early years and initiated OpenAI's first large-scale automated interpretability project; at the time, using raw tools, he found only about 2% of neurons readable, which made him pessimistic. He now believes that most of the obstacles he expected do not exist, and ambitious interpretability may be solved soon because automated scientists continue to improve.

  7. LessWrong
    Link post: neural networks are now clearly readable

    Yair Halberstadt posted a link on LessWrong, relaying Nick Cammarata's long post on mechanistic interpretability, in which he says neural networks are not as entangled and difficult as he once thought. Cammarata says he became pessimistic after early mechanistic interpretability work at OpenAI, but later launched OpenAI's first large-scale automated interpretability project, finding only about 2% of neurons readable with the then-primitive tools; with modern agent tools and more careful observation, the vast majority of neurons in models up to trillion-parameter scale are readable, and many famous cases of entangled neurons are actually misunderstandings. He believes ambitious interpretability will be solved when it is most needed, possibly even soon. Roon quoted and shared it, calling it a potentially important moment in the history of science, while the post author asks how much this advances known results and what use it is for alignment practice.

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