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abrupt representation change

Abrupt representation change refers to the sudden and disruptive modification of a machine learning model internal feature representations when it encounters new, previously unseen data distributions or classes in a sequential learning stream. In continual learning environments, as a neural network attempts to rapidly accommodate unfamiliar concepts alongside historical data, the newly introduced features can heavily interfere or overlap with existing representations, triggering severe parameter adjustments. This rapid reorganization of the latent feature space destabilizes the stability of previously acquired representations, significantly contributing to catastrophic forgetting and impairing the model ability to retain past knowledge while integrating new tasks.

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New Insights on Reducing Abrupt Representation Change in Online Continual Learning

New Insights on Reducing Abrupt Representation Change in Online Continual Learning

Lucas Caccia, Rahaf Aljundi, Nader Asadi, Tinne Tuytelaars, Joelle Pineau, Eugene Belilovsky

OrganizationsConcordia UniversityKU LeuvenMcGill UniversityMetaMilaToyota Motor Europe

Why you should read this

Demonstrates how Experience Replay causes disruptive representation shifts when new classes appear in online continual learning, and resolves this with an asymmetric update rule that forces incoming data to adapt to established representations.

In the online continual learning paradigm, agents must learn from a changing distribution while respecting memory and compute constraints. Experience Replay (ER), where a small subset of past data is stored and replayed alongside new data, has emerged as a simple and effective learning strategy. In this work, we focus on the change in representations of observed data that arises when previously unobserved classes appear in the incoming data stream, and new classes must be distinguished from previous ones. We shed new light on this question by showing that applying ER causes the newly added classes' representations to overlap significantly with the previous classes, leading to highly disruptive parameter updates. Based on this empirical analysis, we propose a new method which mitigates this issue by shielding the learned representations from drastic adaptation to accommodate new classes. We show that using an asymmetric update rule pushes new classes to adapt to the older ones (rather than the reverse), which is more effective especially at task boundaries, where much of the forgetting typically occurs. Empirical results show significant gains over strong baselines on standard continual learning benchmarks.

Added

2026-09-26