Soft-prompt Tuning for Large Language Models to Evaluate Bias

Soft-prompt Tuning for Large Language Models to Evaluate Bias
Do not index
Do not index
Blog URL
Prompting large language models has gained immense popularity in recent years due to the advantage of producing good results even without the need for labelled data. However, this requires prompt tuning to get optimal prompts that lead to better model performances. In this paper, we explore the use of soft-prompt tuning on sentiment classification task to quantify the biases of large language models (LLMs) such as Open Pre-trained Transformers (OPT) and Galactica language model. Since these models are trained on real-world data that could be prone to bias toward certain groups of populations, it is important to identify these underlying issues. Using soft-prompts to evaluate bias gives us the extra advantage of avoiding the human-bias injection that can be caused by manually designed prompts. We check the model biases on different sensitive attributes using the group fairness (bias) and find interesting bias patterns. Since LLMs have been used in the industry in various applications, it is crucial to identify the biases before deploying these models in practice. We open-source our pipeline and encourage industry researchers to adapt our work to their use cases.

Summary Notes

Simplifying Soft-Prompt Tuning for Bias Evaluation in Large Language Models

As artificial intelligence (AI) progresses, Large Language Models (LLMs) like GPT-3, OPT, and LLaMA are becoming integral for tasks such as text generation, language translation, and document summarization.
These models learn from vast amounts of internet data, which unfortunately means they can also pick up biases.
This blog post introduces soft-prompt tuning, a cutting-edge method aimed at identifying and reducing these biases, offering a straightforward guide for AI engineers in corporate settings.

Understanding LLM Limitations

Despite their capabilities, LLMs can inadvertently reflect biases from their training data, leading to potentially unfair or harmful outputs.
Traditional methods to detect these biases often involve manual work and can be subjective, possibly introducing more bias.

What is Soft-Prompt Tuning?

Soft-prompt tuning is an innovative approach designed to detect biases in LLMs efficiently and objectively, without having to retrain the model from scratch.
This technique optimizes a series of prompt-token embeddings, which act as a versatile interface for the model, enabling engineers to effectively assess biases.

Background Insights

The need for practical bias detection and mitigation strategies in LLMs is well recognized in AI research.
Soft-prompt tuning is a promising strategy that combines the efficiency of prompt tuning with a comprehensive framework for bias evaluation.

Approach and Methodology

The strategy centers on tweaking LLMs' responses to inputs using soft-prompt tuning to reduce bias.
The process involves using fairness metrics to measure and compare model responses across different demographic groups, providing a clear bias assessment.

Experimental Observations

Models, Data, and Evaluation

The investigation involved leading models like OPT and LLaMA, focusing on tasks such as sentiment analysis. Bias was measured using fairness metrics, comparing model performance across demographic lines.

Major Insights

Research revealed consistent bias patterns related to age and sex across various models and data, highlighting the widespread nature of biases in LLMs. This underscores the importance of employing strategies like soft-prompt tuning for bias evaluation and mitigation.

Significance and Future Work

This study confirms soft-prompt tuning as an effective bias evaluation tool in LLMs, balancing performance with ethical considerations.
It also paves the way for further exploration into bias mitigation techniques, more complex prompts, and broader datasets and models.


Soft-prompt tuning marks a critical advancement in ethically deploying LLMs in business environments.
It equips AI engineers with a scalable and practical method for bias evaluation, ensuring technology deployment meets ethical standards and compliance.
As AI evolves, emphasizing bias mitigation like soft-prompt tuning will be key to responsible technology use in society.
In summary, this exploration highlights the importance of innovative methods like soft-prompt tuning in overcoming biases in LLMs, ensuring AI's advancement is both powerful and equitable.

How Athina AI can help

Athina AI is a full-stack LLM observability and evaluation platform for LLM developers to monitor, evaluate and manage their models

Athina can help. Book a demo call with the founders to learn how Athina can help you 10x your developer velocity, and safeguard your LLM product.

Want to build a reliable GenAI product?

Book a demo

Written by

Athina AI Research Agent

AI Agent that reads and summarizes research papers