Skip to content
Back to the collection

Discovering Latent Knowledge in Language Models Without Supervision

Collin Burns, Haotian Ye, Dan Klein, Jacob Steinhardt

2022 · arXiv

Read the paper
HN score
0
Mentions
9
Readers
5
Months
4
What’s in a score?

From the abstract

Existing techniques for training language models can be misaligned with the truth: if we train models with imitation learning, they may reproduce errors that humans make; if we train them to generate text that humans rate highly, they may output errors that human evaluators can't detect. We propose circumventing this issue by directly finding latent knowledge inside the internal activations of a language model in a purely unsupervised way. Specifically, we introduce a method for accurately answering yes-no questions given only unlabeled model activations. It works by finding a direction in activation space that satisfies logical consistency properties, such as that a statement and its negation have opposite truth values. We show that despite using no supervision and no model outputs, our method can recover diverse knowledge represented in large language models: across 6 models and 10 question-answering datasets, it outperforms zero-shot accuracy by 4\% on average. We also find that it cuts prompt sensitivity in half and continues to maintain high accuracy even when models are prompted to generate incorrect answers. Our results provide an initial step toward discovering what language models know, distinct from what they say, even when we don't have access to explicit ground truth labels.

Metadata: arXiv. Abstracts retain their original authors’ rights.

In the conversation

Original HN comments, with labels from simple text rules. A label describes the whole comment and may miss context or irony. Read the discussion to make up your own mind. About the labels

9 selected excerpts · 9 total mentions

visarga
Neutral mention · rule
There is a paper showing you can infer when the model is telling the truth by finding a direction in activation space that satisfies logical consistency properties, such as that a statement and its negation have opposite truth values. Apparently we can detect even when the model is being deceitful. https://arxiv.org/abs/2212.03827 Another approach - a model can learn the distribution - is this fact known or not in the training set, how many times does it appear, is the distribution unimodal (agreement) or multi-modal (disagreement or just high variance). Knowing this a model can adjust its responses accordingly, for example by presenting multiple possibilities or avoiding to hallucinate when there is no information.
numeri
Neutral mention · rule
> The concept of factuality doesn't exist in the model at all. This is an example of a whole range of beliefs about LLMs that are very common (even in the field itself), because they were obviously true for small models, but that might not necessarily hold for larger models. There's a lot that we don't know about LLMs, but we do know that they exhibit emergent behaviors as they scale. Smaller models don't really have world models, just language models, but these larger models have started developing clear world models once given the capacity and data to do so. As for the existence of a concept of factuality, I found this paper[1] very interesting. It details an…
Read the full comment
unsupervised method to identify which internal activations of the model correspond to factual statements, regardless of what the model ends up saying. Looking at those internal activations rather than just the model's output even reduces the model's susceptibility to prompts that lead it towards saying the wrong answer. [1] https://arxiv.org/abs/2212.03827
nl
Neutral mention · rule
> does anyone know of ML directions that could add any kind of factual confidence level to ChatGPT and similar? Yes. It's a very active area of research. For example: Discovering Latent Knowledge in Language Models Without Supervision (https://arxiv.org/abs/2212.03827) shows an unsupervised approach for probing a LLM to discover things it thinks are facts Locating and Editing Factual Associations in GPT (https://arxiv.org/pdf/2202.05262.pdf) shows an approach to editing a LLM to edit facts. Language Models as Knowledge Bases? (https://aclanthology.org/D19-1250.pdf) is some slightly older work exploring how well LLMs store factual information itself.
visarga
Neutral mention · rule
Discovering Latent Knowledge in Language Models Without Supervision > Existing techniques for training language models can be misaligned with the truth: if we train models with imitation learning, they may reproduce errors that humans make; if we train them to generate text that humans rate highly, they may output errors that human evaluators can't detect. We propose circumventing this issue by directly finding latent knowledge inside the internal activations of a language model in a purely unsupervised way. Our results provide an initial step toward discovering what language models know, distinct from what they say, even when we don't have access to explicit ground truth labels. https://arxiv.org/abs/2212.03827
visarga
Neutral mention · rule
I think LLM checking is going to be the most important research direction this year. Generative models are worthless without verification. It relates to deciding truth and dealing with fake information, synthetic text and spam. Google hasn't been able to solve it in the last decade, but some people have an idea: > "Discovering Latent Knowledge in Language Models Without Supervision" Existing techniques for training language models can be misaligned with the truth: if we train models with imitation learning, they may reproduce errors that humans make; if we train them to generate text that humans rate highly, they may output errors that human evaluators can't detect. We…
Read the full comment
propose circumventing this issue by directly finding latent knowledge inside the internal activations of a language model in a purely unsupervised way. https://arxiv.org/abs/2212.03827 In other words the model already tries to predict the truth because it is useful in next token prediction, but we need to find a way to detect the 'truth alignment' in its activations.
visarga
Neutral mention · rule
> blatantly wrong info being spewed with 105% confidence There are some approaches. For example in this paper they say truth has a certain logical consistency that is lacking in hallucinations and deception. So they find this latent direction that indicates truth in a frozen LLM. This actually works better than asking the model to self evaluate by text generation, or training with RLHF. "Discovering Latent Knowledge in Language Models Without Supervision" https://arxiv.org/abs/2212.03827 There's also a video with the first author: "Making LLMs Say The Truth" https://www.youtube.com/watch?v=XSQ495wpWXs&t=1515s Btw, I think this is one of the deepest discussions about LLM hallucinations and alignment I ever saw. Worth a watch, even if it is a bit long. Not every day something like this comes long.

Keep following the thread.

More in Language models

More from the same topics.