Research Institute for S
Abstract
Biases in machine learning pose significant challenges, particularly when
models amplify disparities that affect disadvantaged groups. Traditional bias
mitigation techniques often lead to a {\itshape leveling-down effect}, whereby
improving outcomes of disadvantaged groups comes at the expense of reduced
performance for advantaged groups. This study introduces Bias Mitigation
through Continual Learning (BM-CL), a novel framework that leverages the
principles of continual learning to address this trade-off. We postulate that
mitigating bias is conceptually similar to domain-incremental continual
learning, where the model must adjust to changing fairness conditions,
improving outcomes for disadvantaged groups without forgetting the knowledge
that benefits advantaged groups. Drawing inspiration from techniques such as
Learning without Forgetting and Elastic Weight Consolidation, we reinterpret
bias mitigation as a continual learning problem. This perspective allows models
to incrementally balance fairness objectives, enhancing outcomes for
disadvantaged groups while preserving performance for advantaged groups.
Experiments on synthetic and real-world image datasets, characterized by
diverse sources of bias, demonstrate that the proposed framework mitigates
biases while minimizing the loss of original knowledge. Our approach bridges
the fields of fairness and continual learning, offering a promising pathway for
developing machine learning systems that are both equitable and effective.
AI Insights - Just Train Twice (JTT) attains state‑of‑the‑art group robustness without group labels.
- JTT trains two models—one per group—and a combiner that learns a weighted loss.
- The weighted loss balances group performance, boosting robustness without extra data.
- JTT doubles training time and memory, limiting scalability to very large datasets.
- It shows promise in medical imaging and computer vision, where group shifts are common.
- More work is needed to assess residual biases and extend JTT to complex architectures.
- See Liu et al. “Just Train Twice” and Sagawa et al. “Distributionally Robust Neural Networks” for deeper insight.
Ludwig-Maximilian Univers
Abstract
Catastrophic forgetting is a significant challenge in continual learning, in
which a model loses prior knowledge when it is fine-tuned on new tasks. This
problem is particularly critical for large language models (LLMs) undergoing
continual learning, as retaining performance across diverse domains is
important for their general utility. In this paper, we explore model growth, a
promising strategy that leverages smaller models to expedite and structure the
training of larger ones for mitigating the catastrophic forgetting problem.
Although growth-based pretraining, particularly via transformer stacking, has
shown promise in accelerating convergence, its impact on forgetting remains
under-explored. Therefore, we evaluate whether growth-based models can retain
previously learned capabilities more effectively across a sequence of
fine-tuning tasks involving domain knowledge, reasoning, reading comprehension,
and bias. Our findings show that both models -- one trained with growth (Stack
LLM) and one without (LLM) -- exhibit improvements in domain knowledge.
However, reasoning and reading comprehension degrade over time, indicating
signs of catastrophic forgetting. Stack LLM consistently shows less
degradation, especially in reading comprehension, suggesting enhanced retention
capabilities. Interestingly, in bias evaluation, the baseline LLM becomes
progressively more neutral with continued fine-tuning, while Stack LLM
maintains a steady bias ratio around 60--61\%. These results indicate that
growth-based pretraining may deliver modest improvements in resisting
catastrophic forgetting, though trade-offs remain in handling social biases.
AI Insights - CrowS‑pairs is used to track gender and racial bias shifts during continual fine‑tuning.
- A hybrid of knowledge distillation from a frozen teacher and task‑specific fine‑tuning mitigates forgetting.
- Benchmarks on GLUE and other NLP tasks show growth‑based models beat vanilla baselines on domain accuracy.
- The paper cites BERT, RoBERTa, and XLNet to frame its pre‑training strategy.
- Limitations: narrow task set, unreported compute budgets, and training‑from‑scratch assumption.
- Future work: test other distillation objectives and multi‑task curricula for stronger retention.
- Catastrophic Forgetting: loss of prior knowledge when fine‑tuning; Knowledge Distillation: student mimics teacher outputs.