Google's new method ASPIRE: gives LLM self-scoring capabilities, effectively solves the 'illusion' problem, and surpasses 10 times the volume model

The "illusion" problem of large models will soon be solved?

Researchers at the University of Wisconsin-Madison and Google recently launched the ASPIRE system, which enables large models to self-evaluate their output.

If the user sees that the result generated by the model has a low score, they will realize that the reply may be an illusion.

If the system can further filter the output based on the score, for example when the score is low, the large model can generate something like "I can't answer this question" " statement, which may improve the hallucination problem to the greatest extent.

Paper address: https://aclanthology.org/2023.findings-emnlp.345.pdf

ASPIRE allows LLM to output the answer and the confidence score of the answer.

The researchers’ experimental results show that ASPIRE significantly outperforms traditional selective prediction methods on various QA datasets such as the CoQA benchmark.

Let LLM not only answer questions, but also evaluate those answers.

In the benchmark test of selective prediction, the researchers achieved results of more than 10 times the scale of the model through the ASPIRE system.

It’s like asking students to verify their own answers at the back of the textbook. Although it sounds a bit unreliable, if you think about it carefully, everyone After completing a question, there will indeed be a score for the degree of satisfaction with the answer.

This is the essence of ASPIRE, which involves three phases:

(1) Tuning for a specific task,

(2) Answer sampling,

(3) Self-assessment learning.

In the eyes of researchers, ASPIRE is not just another framework, it represents a bright future that comprehensively improves LLM reliability and reduces hallucinations. .

If LLM can become a trusted partner in the decision-making process.

By continuously optimizing the ability to make selective predictions, humans are one step closer to fully realizing the potential of large models.

Researchers hope to use ASPIRE to start the evolution of the next generation of LLM, thereby creating more reliable and self-aware artificial intelligence.

ASPIRE’s mechanics

Fine-tuning for specific tasks

ASPIRE performs task-specific fine-tuning to train adaptive parameters while freezing the LLM. Given a training dataset for the generation task, it fine-tunes the pre-trained LLM to improve its prediction performance.

To this end, parameter-efficient fine-tuning techniques (e.g., soft-cue word fine-tuning and LoRA) can be employed to fine-tune pre-trained LLMs on the task, as they can be efficiently obtained with a small number of targets Strong generalization task data.

Specifically, the LLM parameters (θ) are frozen, and adaptive parameters

are added for fine-tuning. Only update θ (p) to minimize the standard LLM training loss (e.g. cross-entropy).

This kind of fine-tuning can improve selective prediction performance because it not only improves prediction accuracy, but also increases the likelihood of correctly outputting the sequence.

Answer sampling

## After being tuned for a specific task, ASPIRE uses LLM and learned Generate different answers for each training question and create a dataset for self-evaluation learning.

The researcher’s goal is to generate output sequences with high likelihood. They used Beam Search as the decoding algorithm to generate high-likelihood output sequences and used the Rouge-L metric to determine whether the generated output sequences were correct.

Self-evaluation learning

After sampling the high-likelihood output for each query, ASPIRE adds self-evaluation Adapt parameters and fine-tune only to learn self-evaluation.

Since the generation of the output sequence depends only on θ and , freezing θ and the learned can be avoided Changing LLM's predictive behavior when learning self-evaluation.

The researchers optimized so that the adapted LLM can distinguish correct and incorrect answers on its own.

In this framework, any parameter-valid fine-tuning method can be used to train and .

In this work, the researchers used soft-cue fine-tuning, a simple yet effective mechanism for learning "soft cues" to tune frozen language models, thereby Perform specific downstream tasks more efficiently than traditional discrete text prompts.

The core behind this approach is the recognition that if cues can be developed that effectively stimulate self-evaluation, it should be discoverable through fine-tuning of soft cues combined with targeted training goals These tips.

After training and , the researchers decoded by beam search Get predictions for the query (beam search decoding).

The researchers then define a choice score that combines the likelihood of generating an answer with the learned self-assessment score (i.e., the likelihood that the prediction is correct for the query) to do Make selective predictions.

Results

To demonstrate the effect of ASPIRE, the researchers used various open pre-trained Transformer (OPT) models on three question and answer data Evaluate it on the set (CoQA, TriviaQA and SQuAD).

By adjusting training using soft cuesThe researchers observed a substantial improvement in the accuracy of LLM.

For example, the OPT-2.7B model with ASPIRE showed better performance than the larger pre-trained OPT-30B model using the CoQA and SQuAD datasets.

These results suggest that with appropriate tuning, smaller LLMs may have the ability to match or possibly exceed the accuracy of larger models in some situations.

When delving into the calculation of selection scores for fixed model predictions, ASPIRE achieved higher AUROC scores than the baseline method for all datasets (random The probability that a selected correct output sequence has a higher selection score than a randomly selected incorrect output sequence).

For example, on the CoQA benchmark, ASPIRE improves AUROC from 51.3% to 80.3% compared to the baseline.

An interesting pattern emerged from the evaluation of the TriviaQA dataset.

Although the pre-trained OPT-30B model exhibits higher baseline accuracy, its choice when applying traditional self-evaluation methods (Self-eval and P(True)) The performance of sex prediction is not significantly improved.

In contrast, the much smaller OPT-2.7B model outperformed other models in this regard after being enhanced with ASPIRE.

This difference reflects an important issue: larger LLMs that utilize traditional self-assessment techniques may not be as effective at selective prediction as smaller ASPIRE-enhanced models.

The researchers’ experimental journey with ASPIRE highlights a key shift in the LLM landscape: A language model’s capacity is not the be-all and end-all of its performance .

Instead, model effectiveness can be greatly improved through policy adjustments, allowing for more accurate and confident predictions even in smaller models.

Thus, ASPIRE demonstrates the potential of LLMs to sensibly determine the certainty of their own answers and significantly outperform others 10 times their size in selective prediction tasks. Model.

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