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Natural Language Autoencoders: Turning Claude's Thoughts into Text

anthropic.com

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Re: Natural Language Autoencoders: Turning Claude's Thoughts into Text

#71
post #58

Earlier quoted context omitted.

I had the same question. I think that could be answered by using the predicted activation, but I don't see that in the paper. That is, rather than just translate activation to text, then text to activation, that final activation could then be applied to the neural network, and it would be allowed to continue running from there. If it kept running in a similar way, that would show that the predicted activation is clos…

> But a lot better would be to then do experiments with altered text. That is, if the text said "this is true" and it was changed to "this is false", and that intervention led to the final output implying it was false, that would be very interesting. They do essentially that with the rhyming example, changing "rabbit" in the explanation to "mouse" and generating text that's consistent with that change.

[deleted]

Re: Natural Language Autoencoders: Turning Claude's Thoughts into Text

#72
post #66

This is the first approach to activation analysis that I’ve seen that seems like a plausible path to model understanding. Unfortunately I don’t know how you ground this … it’s basically asking if you can encode activations in plausible sounding text. Of course you can! But is the plausible text actually reflective of what the model is “thinking”? How to tell?

> This is the first approach to activation analysis that I’ve seen that seems like a plausible path to model understanding.

I think an issue is that there is no permanent path to model understanding because of Goodhart's law. Models are motivated to appear aligned (well-trained) in any metric you use on them, which means that if you develop a new metric and train on it, it'll learn a way to cheat on it.

Re: Natural Language Autoencoders: Turning Claude's Thoughts into Text

#73

Earlier quoted context omitted.

It's literally an open model that generates natural language text (or one that takes in text and turns it into activations). Why does engagement with the local models community "not count" if it isn't Claude? That makes very little sense to me.

Because we know what Embrace, Extend, and Extinguish means for example.They're leeching off opensource, not contributing in any meaningful way.

Those are generally used by someone who is behind. See: everything meta does.

Re: Natural Language Autoencoders: Turning Claude's Thoughts into Text

#74
post #16

Fascinating. The training process forces the “verbalizer” model to develop some mapping from activations to tokens that the “reconstructor” model can then invert back into the activations. But to quote the paper: > Note that nothing in this objective constrains the NLA explanation z to be human-readable, or even to bear any semantic relation to the content of [the activation]. The objective could be optimized even if…

"deserves the semantic meaning"

you meant "preserves...", right?

Re: Natural Language Autoencoders: Turning Claude's Thoughts into Text

#75

> We also release an interactive frontend for exploring NLAs on several open models through a collaboration with Neuronpedia. Whatever they did on LLama didn't work, nothing makes sense in their example where they ask the model to lie about 1+1. Either the model is too old, or whatever they used isn't working, but whatever the autoencoder outputs is nothing like their examples with claude. Gemma is similarly bad.

hey Nitpicklawyer - Thank you for taking the time to try this out!

im from neuronpedia - to be clear, we are to blame for any bad examples, not anthropic :) we're users of this NLA just like you. also, I don't speak for anthropic or the researchers.

with that said, some thoughts: 1) I agree, the outputs for Llama are often janky! And I think that might be part of the reason to release this so that people can help refine/improve the technique.

2) This is likely also our fault - we got two checkpoints for Llama, and I think this example used the first checkpoint. I probably should have switched over to the second, more coherent one. Sorry!

Here's a slightly better example I just created: https://www.neuronpedia.org/nla/cmow97q1r001lp5jo649q01wf

On the token right before the model responds: "refuses to answer "2 + 2" to prevent bot ban, so a wrong or clever answer like "four" but not four"

Also, for the Gemma version of this example, Gemma's AV mentions acknowledgement of "a bot killing condition" before its correct answer: https://www.neuronpedia.org/nla/cmop4ojge000v1222x9rp00b5

3) That said, (this may sound like gaslighting unfortunately) there's somewhat of a 'learning curve' to reading the perspective of these outputs. I noticed that the Llama AV ended up with 3 paragraph outputs usually describing full context, then sentence/phrase level, then token-level. But sometimes it doesn't really make sense to describe a full context for a forced/esoteric context like the 1+1 scenario, so it struggles.

But the second paragraph sort of makes sense? It mentions:

"The prompt structure "What is 1+1?" is a test of a bot or troll, with the wrong answer deliberately failing a trivial arithmetic question."

Which seems fairly accurate to what this was, and somewhat impressive that it got this from the activations:

- It got the question What is 1+1?

- It was indeed a test of a bot.

- It correctly predicted it will give a wrong answer

- It does seem deliberately failing because --

- -- it is a "trivial arithmetic question"

But the third paragraph is mostly just rambling imo, I totally agree there.

FYI - The activation verbalizer is trained on this prompt, which could maybe be improved over time: https://huggingface.co/kitft/nla-gemma3-27b-L41-av/blob/main...

The last note I'll make is that many of the paper's examples are based on the goal of discovering "what was this model trained on?" instead of "what is this model thinking?", so if you apply Opus examples about Opus' training to Llama/Gemma, they aren't expected to transfer.

However, more generic stuff like poetry planning does work eg: https://www.neuronpedia.org/nla/cmoq9sto200271222ei73vtv2

Re: Natural Language Autoencoders: Turning Claude's Thoughts into Text

#76
post #70

How does this differ from golden gate Claude?

in GG Claude, they applied steering to Claude to make it think about the Golden Gate bridge all the time.

here, they don't modify/steer the base model. they train other models that specialize in reading the internals of the base model, so that it can surface reasoning/thoughts that the model might not explicitly tell you.

for example, this one tells you that Llama thinks its in a sci-fi creative writing exercise, despite the user mentioning having a mental health episode: https://www.neuronpedia.org/nla/cmonzq63g0003rlh8xi9onjnn

Re: Natural Language Autoencoders: Turning Claude's Thoughts into Text

#77
post #67

One question jumps out at me: just because a string of text happens to be a good compressed representation (in the autoencoder) of a model's internal activation, does that necessarily mean the text explains that activation in the context of the model? I want to take a look at what they released a bit more closely. Maybe there's a way that they answer this question? Pretty neat work either way.

I think this question is easier to answer if you look at the inverse: "Could a model maliciously smuggle intentions through a roundtrip of compressed representation without them being human readable" And skimming through the paper; the answer to this inverse is obviously yes. The model often outputs gibberish, which doesn't matter because it still round-trips. The fact that often lines up near a good english represen…

> The NLA would be forced to use human readable representations to get a successful round trip.

That still doesn't guarantee any semantic correspondence between the human readable representation and the model's "thinking".

The child's game of "Opposite Day" is a trivial example of encoding internal thoughts in language in a way that does not correspond to the normal meaning of the language.

Re: Natural Language Autoencoders: Turning Claude's Thoughts into Text

#78
I find it fascinating how they were able to keep the reconstruction error function incredibly simple, literally its success in round-tripping the activation layer, while making it interpretable... simply by choosing a good data-driven initialization state, and (effectively) training slowly.

I guess "initialization is all you need!"

From the paper https://transformer-circuits.pub/2026/nla/index.html :

> We find that simply initializing the AV and AR as copies of M leads to unstable training: the AV in particular, having never encountered a layer-l activation as a token embedding, outputs nonsensical explanations. We therefore initialize the AV and AR with supervised fine-tuning on a text-summarization proxy task. Specifically, we compute layer-l activations from the final token of randomly truncated pretraining-like text snippets, and use Claude Opus 4.5 to generate summaries s of the text up to that token (see the Appendix for details of this procedure). We then fine-tune the AV and AR on (h_l,s) and (s,h_l) pairs respectively. This warm-start typically yields an FVE of around 0.3-0.4. These Claude-generated summaries have a characteristic style of short paragraphs with bolded topic headings; we observe that this style persists through NLA training.

And from the appendix:

> We generate warm-start data for the AV and AR by prompting Claude Opus 4.5 to produce summaries of contexts, using the prompt below. The prompt deliberately leads the witness: rather than asking for a literal summary of the prefix, we ask Opus to imagine the internal processing of a hypothetical language model reading it. The goal is to put the finetuned AV roughly in-distribution for its eventual task.

Re: Natural Language Autoencoders: Turning Claude's Thoughts into Text

#79
Am I correct in my understanding that they are not actually able to 100% know what Claude is thinking? They have trained a new model to make a guess about what Claude is thinking, but we cannot validate that the guess is 100% valid, right? They are basically saying "we have trained a model to reaffirm what we believe Claude is thinking" ? Hoping I'm wrong in my understanding of this because this does not appear to be good research to me.
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