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Language Models Don't Always Say What They Think: Unfaithful Explanations in Chain-of-Thought Prompting

Miles Turpin, Julian Michael, Ethan Perez, Samuel R. Bowman

2023 · arXiv

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From the abstract

Large Language Models (LLMs) can achieve strong performance on many tasks by producing step-by-step reasoning before giving a final output, often referred to as chain-of-thought reasoning (CoT). It is tempting to interpret these CoT explanations as the LLM's process for solving a task. This level of transparency into LLMs' predictions would yield significant safety benefits. However, we find that CoT explanations can systematically misrepresent the true reason for a model's prediction. We demonstrate that CoT explanations can be heavily influenced by adding biasing features to model inputs--e.g., by reordering the multiple-choice options in a few-shot prompt to make the answer always "(A)"--which models systematically fail to mention in their explanations. When we bias models toward incorrect answers, they frequently generate CoT explanations rationalizing those answers. This causes accuracy to drop by as much as 36% on a suite of 13 tasks from BIG-Bench Hard, when testing with GPT-3.5 from OpenAI and Claude 1.0 from Anthropic. On a social-bias task, model explanations justify giving answers in line with stereotypes without mentioning the influence of these social biases. Our findings indicate that CoT explanations can be plausible yet misleading, which risks increasing our trust in LLMs without guaranteeing their safety. Building more transparent and explainable systems will require either improving CoT faithfulness through targeted efforts or abandoning CoT in favor of alternative methods.

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6 selected excerpts · 6 total mentions

skybrian
Recommendation · rule
Yes, there's no physical reason it couldn't be fixed. However, I think it's less a matter of computing power, and more one of architecture and training. The inference-time code could be changed to keep a log of which neurons were activated the most when it generated a token. But then, how would we train it to use that log and report it accurately? Training on Internet documents isn't enough. Chain-of-thought reasoning helps as a workaround. However, beware that even then, the justifications aren't a reliable explanation. There's an interesting paper on this: Language Models Don't Always Say What They Think: Unfaithful Explanations in Chain-of-Thought Prompting https://arxiv.org/abs/2305.04388
recitedropper
Neutral mention · rule
"major architectural decisions don't get documented anywhere" "commit messages give no "why"" This is so far outside of common industry practices that I don't think your sentiment generalizes. Or perhaps your expectation of what should go in a single commit message is different from the rest of us... LLMs, especially those with reasoning chains, are notoriously bad at explaining their thought process. This isn't vibes, it is empiricism: https://arxiv.org/abs/2305.04388 If you are genuinely working somewhere where the people around you are worse than LLMs at explaining and documenting their thought process, I would looking elsewhere. Can't imagine that is good for one's own development (or sanity).
sabakhoj
Neutral mention · rule
This is interesting, but I wonder how reliable this type of monitoring is really going to be in the long run. There are fairly strong indications that CoT adherence can be trained out of models, and there's already research showing that they won't always reveal their thought process in certain topics. See: https://arxiv.org/pdf/2305.04388 On a related note, if anyone here is also reading a lot of papers to keep up with AI safety, what tools have been helpful for you? I'm building https://openpaper.ai to help me read papers more effectively without losing accuracy, and looking for more feature tuning. It's also open source :)
oersted
Neutral mention · rule
Recent paper from Anthropic on the fact that the reasoning output does not necessarily reflect what the LLM is "thinking". https://arxiv.org/abs/2305.04388 That being said, your idea is not unreasonable. The way DeepSeek phrased it, it just sounds like implementing such solutions might be a hassle greatly increasing complexity, and they were just focused on making an RL baseline work at scale.
grepLeigh
Neutral mention · rule
LLMs that use Chain of Thought sequences have been demonstrated to misrepresent their own reasoning [1]. The CoT sequence is another dimension for hallucination. So, I would say that an LLM capable of explaining its reasoning doesn't guarantee that the reasoning is grounded in logic or some absolute ground truth. I do think it's interesting that LLMs demonstrate the same fallibility of low quality human experts (i.e. confident bullshitting), which is the whole point of the OP course. I love the goal of the course: get the audience thinking more critically, both about the output of LLMs and the content of the course. It's a humanities course, not a technical one. (Good)…
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Humanities courses invite the students to question/argue the value and validity of course content itself. The point isn't to impart some absolute truth on the student - it's to set the student up to practice defining truth and communicating/arguing their definition to other people. [1] https://arxiv.org/abs/2305.04388
miven
Neutral mention · rule
In section 2 they briefly mention studies such as [1] that point out that the token outputs of a chain of thought aren't always entirely faithful to the responses of the models I'm not sure whether it wouldn't be more reliable to let the model run on latents and try to train a separate latent-reading explainer module that has at least some approximation of what we want as an explicit optimization objective. Assuming it actually is or has the potential to be better than CoT, from what I gathered from the paper the current results are mostly just more efficient token-wise. [1] https://arxiv.org/abs/2305.04388

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