Distinguishing the Knowable from the Unknowable with Language Models

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Hauptverfasser: Ahdritz, Gustaf, Qin, Tian, Vyas, Nikhil, Barak, Boaz, Edelman, Benjamin L.
Format: Preprint
Veröffentlicht: 2024
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author Ahdritz, Gustaf
Qin, Tian
Vyas, Nikhil
Barak, Boaz
Edelman, Benjamin L.
author_facet Ahdritz, Gustaf
Qin, Tian
Vyas, Nikhil
Barak, Boaz
Edelman, Benjamin L.
contents We study the feasibility of identifying epistemic uncertainty (reflecting a lack of knowledge), as opposed to aleatoric uncertainty (reflecting entropy in the underlying distribution), in the outputs of large language models (LLMs) over free-form text. In the absence of ground-truth probabilities, we explore a setting where, in order to (approximately) disentangle a given LLM's uncertainty, a significantly larger model stands in as a proxy for the ground truth. We show that small linear probes trained on the embeddings of frozen, pretrained models accurately predict when larger models will be more confident at the token level and that probes trained on one text domain generalize to others. Going further, we propose a fully unsupervised method that achieves non-trivial accuracy on the same task. Taken together, we interpret these results as evidence that LLMs naturally contain internal representations of different types of uncertainty that could potentially be leveraged to devise more informative indicators of model confidence in diverse practical settings.
format Preprint
id arxiv_https___arxiv_org_abs_2402_03563
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Distinguishing the Knowable from the Unknowable with Language Models
Ahdritz, Gustaf
Qin, Tian
Vyas, Nikhil
Barak, Boaz
Edelman, Benjamin L.
Machine Learning
Artificial Intelligence
Computation and Language
We study the feasibility of identifying epistemic uncertainty (reflecting a lack of knowledge), as opposed to aleatoric uncertainty (reflecting entropy in the underlying distribution), in the outputs of large language models (LLMs) over free-form text. In the absence of ground-truth probabilities, we explore a setting where, in order to (approximately) disentangle a given LLM's uncertainty, a significantly larger model stands in as a proxy for the ground truth. We show that small linear probes trained on the embeddings of frozen, pretrained models accurately predict when larger models will be more confident at the token level and that probes trained on one text domain generalize to others. Going further, we propose a fully unsupervised method that achieves non-trivial accuracy on the same task. Taken together, we interpret these results as evidence that LLMs naturally contain internal representations of different types of uncertainty that could potentially be leveraged to devise more informative indicators of model confidence in diverse practical settings.
title Distinguishing the Knowable from the Unknowable with Language Models
topic Machine Learning
Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2402.03563