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TrainingFoundations Updated 2026

Catastrophic Forgetting

The tendency of a neural network to lose previously learned abilities when trained on new data — a key challenge for continually updating models.

When a network is trained on a new task, gradient updates can overwrite the weights that encoded earlier knowledge, erasing prior skills — catastrophic forgetting. Kirkpatrick et al. (2017) addressed it with Elastic Weight Consolidation, which slows learning on the weights most important to past tasks, letting a model retain old abilities while learning new ones.

It is a central obstacle to continual learning and to fine-tuning models without degrading their general capabilities.

References

Primary, peer-reviewed and archival sources for this definition.

Overcoming catastrophic forgetting in neural networks
Kirkpatrick, J., Pascanu, R., Rabinowitz, N., Veness, J., Desjardins, G., et al. (2017). Proceedings of the National Academy of Sciences (PNAS), 114(13), 3521–3526.

Dictionary & encyclopedic entries

Cite this entry

MultipleChat. "Catastrophic Forgetting." MultipleChat AI & LLM Glossary, 2026. https://multiple.chat/ai-glossary/catastrophic-forgetting

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