Sebra: Debiasing Through Self-Guided Bias Ranking

TL;DR

Sebra introduces an automatic, self-guided bias ranking method that mitigates spurious correlations in data by leveraging the difficulty of learning samples, improving debiasing performance without human supervision.

Contribution

The paper proposes a novel self-guided bias ranking framework that dynamically steers ERM training to learn attributes in order of increasing spuriosity, enabling unsupervised bias mitigation.

Findings

Outperforms previous unsupervised debiasing methods on multiple benchmarks.

Effectively ranks data points by spuriosity without human supervision.

Enhances bias mitigation in complex datasets like ImageNet-1K.

Abstract

Ranking samples by fine-grained estimates of spuriosity (the degree to which spurious cues are present) has recently been shown to significantly benefit bias mitigation, over the traditional binary biased-\textit{vs}-unbiased partitioning of train sets. However, this spuriosity ranking comes with the requirement of human supervision. In this paper, we propose a debiasing framework based on our novel \ul{Se}lf-Guided \ul{B}ias \ul{Ra}nking (\emph{Sebra}), that mitigates biases (spurious correlations) via an automatic ranking of data points by spuriosity within their respective classes. Sebra leverages a key local symmetry in Empirical Risk Minimization (ERM) training -- the ease of learning a sample via ERM inversely correlates with its spuriousity; the fewer spurious correlations a sample exhibits, the harder it is to learn, and vice versa. However, globally across iterations, ERM tends to deviate from this symmetry. Sebra dynamically steers ERM to correct this deviation, facilitating the sequential learning of attributes in increasing order of difficulty, \ie, decreasing order of spuriosity. As a result, the sequence in which Sebra learns samples naturally provides spuriousity rankings. We use the resulting fine-grained bias characterization in a contrastive learning framework to mitigate biases from multiple sources. Extensive experiments show that Sebra consistently outperforms previous state-of-the-art unsupervised debiasing techniques across multiple standard benchmarks, including UrbanCars, BAR, CelebA, and ImageNet-1K. Code, pre-trained models, and training logs are available at https://kadarsh22.github.io/sebra_iclr25/.