Manipulating and Mitigating Generative Model Biases without Retraining

TL;DR

This paper introduces a fast, model-free method to manipulate and mitigate biases in text-to-image generative models by adjusting their language embeddings, enabling bias control and prompt engineering without retraining.

Contribution

It presents a novel technique leveraging vector algebra in language embeddings to control biases and generate implausible images, also highlighting potential backdoor attack risks.

Findings

Effective bias balancing across social dimensions

Achieved up to 100% success rate in backdoor attacks

Enabled precise prompt engineering without retraining

Abstract

Text-to-image (T2I) generative models have gained increased popularity in the public domain. While boasting impressive user-guided generative abilities, their black-box nature exposes users to intentionally- and intrinsically-biased outputs. Bias manipulation (and mitigation) techniques typically rely on careful tuning of learning parameters and training data to adjust decision boundaries to influence model bias characteristics, which is often computationally demanding. We propose a dynamic and computationally efficient manipulation of T2I model biases by exploiting their rich language embedding spaces without model retraining. We show that leveraging foundational vector algebra allows for a convenient control over language model embeddings to shift T2I model outputs and control the distribution of generated classes. As a by-product, this control serves as a form of precise prompt engineering to generate images which are generally implausible using regular text prompts. We demonstrate a constructive application of our technique by balancing the frequency of social classes in generated images, effectively balancing class distributions across three social bias dimensions. We also highlight a negative implication of bias manipulation by framing our method as a backdoor attack with severity control using semantically-null input triggers, reporting up to 100% attack success rate. Key-words: Text-to-Image Models, Generative Models, Bias, Prompt Engineering, Backdoor Attacks