Improving Language Models with REAL Sampling
A new approach enhances accuracy and creativity in language model outputs.
― 5 min read
Table of Contents
Language models, or LLMs, are tools used to generate text. They work by predicting what comes next based on a given input. However, many of these models struggle with accuracy and creativity at the same time. When they generate text, they can produce false information while also being repetitive or lacking in variety. These problems are often referred to as issues with Factuality and Diversity.
To tackle these concerns, researchers have been looking for better ways to guide how LLMs create responses. A popular method called nucleus sampling, which picks from a range of possible next words based on their likelihood, has been widely used. However, there is a tradeoff: increasing the diversity of responses may lead to more incorrect information. This paper introduces a new method called REAL sampling that aims to improve both factuality and diversity without sacrificing one for the other.
The Challenge of Hallucination
One major setback with LLMs is a problem known as hallucination. This is when the model generates information that is either made up or incorrect. For example, it might confidently state a false fact because it has perceived it to be likely based on its training data. This is particularly concerning in open-ended tasks where the model is expected to provide accurate and informative outcomes.
Research shows that LLMs can sometimes be aware of their inaccuracies, indicating that the way they generate text can significantly contribute to hallucination. Current sampling methods might not adequately address this issue, hence the need for new strategies.
REAL Sampling: An Overview
REAL sampling is a new method designed to tackle the dual problems of hallucination while improving diversity. The foundation of this method is a model that predicts when the language model might generate false information. By doing so, REAL sampling can adjust its selection process. If there’s a high chance of an error, it can narrow down the focus to more reliable words. Conversely, when the chances of making an error are low, it can widen the selection to include more diverse options.
The method also relies on smaller models that can accurately predict the likelihood of hallucination. Even though these smaller models do not possess all the data of their larger counterparts, they can still provide useful insights to adjust the sampling process.
How REAL Sampling Works
At its core, REAL sampling modifies the traditional sampling process by incorporating a technique to estimate the Uncertainty of word predictions. This is done by examining how the model's predictions change with increasing size. Larger models generally produce more reliable predictions, so by observing how their outputs differ, we can get a sense of the inherent uncertainty related to the next word choices.
The sampling process involves:
Prediction of Uncertainty: By analyzing the outputs of variously sized models, REAL sampling estimates a threshold value for the next token based on the uncertainty observed.
Adjustment of Selection: With this uncertainty in hand, REAL sampling can adjust the likelihood of choosing a particular word. If the uncertainty is high, fewer words are chosen. If it is low, more options are available, promoting diversity.
Optimization: The method continually optimizes by comparing the factual accuracy of generated content against known reliable data, such as Wikipedia articles.
Performance Evaluation
To assess the effectiveness of REAL sampling, various benchmarks and comparisons against existing methods were conducted. A notable benchmark was the FactualityPrompts, which provides a structured way to evaluate the accuracy of generated sentences by comparing them to factual statements.
The results indicated that sentences generated using REAL sampling contained significantly fewer inaccuracies and were more diverse compared to sentences generated from traditional methods like greedy and nucleus sampling. These improvements in both factuality and diversity were consistent across different models.
Human Evaluation
In addition to automated evaluations, human assessments were also carried out to gauge the perceived quality of the outputs. Participants were asked to evaluate several aspects such as factuality, fluency, and overall quality of the text generated by different methods.
The feedback revealed a notable preference for REAL sampling over traditional methods. Participants reported that the generated text was not only more accurate but also more interesting and easier to read.
Implications for Future Applications
The advancements made with REAL sampling could have significant implications across various fields that rely on language generation. For instance:
Chatbots and Virtual Assistants: As these tools become more integrated into daily life, ensuring they provide accurate and diverse responses is critical. REAL sampling could enhance their reliability.
Content Creation: Writers and marketers can benefit from tools that generate ideas or content with a higher degree of accuracy and variety, potentially revolutionizing how content is produced.
Education: Language models that accurately present information can serve as valuable educational tools, providing students with reliable data for their studies.
Conclusion
REAL sampling presents a promising approach to overcoming long-standing challenges in language model performance. By addressing both factuality and diversity, this method demonstrates that it is possible to improve the storytelling capabilities of LLMs. As the research continues and REAL sampling is refined, its potential applications in various domains may reshape how we view and interact with language technology.
With the foundation laid by REAL sampling, it is clear that significant strides can be made in the field of language generation, ensuring that these increasingly powerful models serve as accurate and reliable sources of information and creativity.
The future of LLMs looks bright, with innovative methodologies like REAL sampling paving the way for more effective and trustworthy applications across multiple sectors. Continued exploration in this field will undoubtedly yield even more sophisticated tools and strategies that enhance our interaction with language models, making them more beneficial to society as a whole.
Title: REAL Sampling: Boosting Factuality and Diversity of Open-Ended Generation via Asymptotic Entropy
Abstract: Decoding methods for large language models (LLMs) usually struggle with the tradeoff between ensuring factuality and maintaining diversity. For example, a higher p threshold in the nucleus (top-p) sampling increases the diversity but decreases the factuality, and vice versa. In this paper, we propose REAL (Residual Entropy from Asymptotic Line) sampling, a decoding method that achieves improved factuality and diversity over nucleus sampling by predicting an adaptive threshold of $p$. Specifically, REAL sampling predicts the step-wise likelihood of an LLM to hallucinate, and lowers the p threshold when an LLM is likely to hallucinate. Otherwise, REAL sampling increases the p threshold to boost the diversity. To predict the step-wise hallucination likelihood without supervision, we construct a Token-level Hallucination Forecasting (THF) model to predict the asymptotic entropy (i.e., inherent uncertainty) of the next token by extrapolating the next-token entropies from a series of LLMs with different sizes. If a LLM's entropy is higher than the asymptotic entropy (i.e., the LLM is more uncertain than it should be), the THF model predicts a high hallucination hazard, which leads to a lower p threshold in REAL sampling. In the FactualityPrompts benchmark, we demonstrate that REAL sampling based on a 70M THF model can substantially improve the factuality and diversity of 7B LLMs simultaneously, judged by both retrieval-based metrics and human evaluation. After combined with contrastive decoding, REAL sampling outperforms 9 sampling methods, and generates texts that are more factual than the greedy sampling and more diverse than the nucleus sampling with $p=0.5$. Furthermore, the predicted asymptotic entropy is also a useful unsupervised signal for hallucination detection tasks.
Authors: Haw-Shiuan Chang, Nanyun Peng, Mohit Bansal, Anil Ramakrishna, Tagyoung Chung
Last Update: 2024-06-11 00:00:00
Language: English
Source URL: https://arxiv.org/abs/2406.07735
Source PDF: https://arxiv.org/pdf/2406.07735
Licence: https://creativecommons.org/licenses/by/4.0/
Changes: This summary was created with assistance from AI and may have inaccuracies. For accurate information, please refer to the original source documents linked here.
Thank you to arxiv for use of its open access interoperability.
Reference Links
- https://medialab.di.unipi.it/wiki/
- https://github.com/jcpeterson/openwebtext
- https://github.com/AI21Labs/factor
- https://github.com/balevinstein/Probes/
- https://github.com/microsoft/HaDes
- https://github.com/nayeon7lee/FactualityPrompt
- https://platform.openai.com/playground?mode=chat
- https://nips.cc/public/guides/CodeSubmissionPolicy
- https://neurips.cc/public/EthicsGuidelines