Overcoming Catastrophic Forgetting During Domain Adaptation of Seq2seq Language Generation
Dingcheng LiZheng ChenEunah ChoJie HaoXiaohu LiuFan XingChenlei GuoYang Liu
Proposes a framework combining adaptive parameter regularization with embedding-space domain drift estimation to prevent catastrophic forgetting in sequential sequence-to-sequence language generation without storing past task data.
Modern language generation systems, such as automated dialog assistants and paraphrasing tools, frequently struggle with catastrophic forgetting. When these sequence-to-sequence models are updated with data from a new domain or task, they tend to forget what they previously learned. Existing continuous learning solutions typically demand substantial extra memory storage to save past data samples for replay or fail to correct representation shifts between differing domains. As organizations deploy conversational artificial intelligence across expanding sets of features and operational environments, retaining previous knowledge without incurring massive storage overhead has become a critical challenge.
The article develops and evaluates a framework called RMR_DSE to mitigate catastrophic forgetting during sequential domain adaptation in text generation models. The approach demonstrates how models can acquire new domain skills while preserving prior capabilities without storing raw data from earlier training phases.
The proposed framework integrates two complementary techniques: a Regularized Memory Recall (RMR) mechanism and a Domain Shift Estimation (DSE) algorithm. RMR enhances training loss by selectively penalizing changes to critical parameters from prior models using gradient-based importance weights and vocabulary-ratio adjustments. DSE estimates semantic drift in internal representation spaces between consecutive models via unsupervised clustering and shifts, which is then subtracted during inference on past domains. The authors evaluated the system across two distinct generation benchmarks: sequential paraphrase generation (using over 270,000 sentence pairs across Quora, Twitter, and Wikipedia datasets) and task-oriented dialog response generation (using the multi-domain MultiWOZ-2.0 dataset across six domains and seven intent categories), testing standard architectures including BART, CVAE, and SCLSTM.
Experimental results show that the framework consistently outperforms standard sequential fine-tuning and state-of-the-art lifelong learning baselines on both current and historical tasks. In paraphrase generation, RMR_DSE achieved higher accuracy across all sequential test orderings, improving generation quality metrics by 3–9% over basic fine-tuning and significantly reducing performance drop when tested on earlier datasets. In dialog response generation without stored exemplars, the system dramatically reduced average slot error rates on previous domains from roughly 64–67% down to 48–52%, while maintaining higher text generation accuracy. When evaluated on initial task retention after learning all six dialog domains, the method cut error rates nearly in half compared to fine-tuning, reducing slot error from over 100% to 57–68%.
These findings indicate that artificial intelligence systems can expand into new domains without requiring burdensome archival databases of previous user interactions. This capability minimizes data storage costs, mitigates user privacy risks associated with long-term data retention, and improves the reliability of deployed natural language systems. Organizations can maintain stable conversational quality without having to retrain models from scratch across entire combined datasets every time a new business domain is added.
Engineering and product teams developing conversational systems should consider adopting adaptive regularization and domain shift estimation pipelines for sequential deployments. Teams can implement this approach as a lightweight drop-in optimizer and loss function adjustment without modifying underlying model architectures. For next steps, teams should pilot the framework across additional text generation tasks, such as automated summarization and machine translation, while experimenting with token-level drift estimation and deep contrastive learning objectives to further refine semantic alignment across domains.
While the empirical findings demonstrate strong confidence across two established text generation benchmarks, several operational considerations remain. The framework requires hyperparameter tuning—such as penalty weights and cluster numbers—that varies based on the structural complexity of the underlying neural network. In addition, semantic drift estimation showed modest improvements when embedding values between domains exhibited similar distributions. Stakeholders should validate cluster settings and parameter sensitivity on domain-specific pilot data before full-scale production rollouts.
- Paper: Memory Aware Synapses: Learning what (not) to forget, Rahaf Aljundi et al. (2017). Its synapse-importance method establishes how to protect parameters crucial to prior tasks, the regularization idea RMR adapts for sequential generation.
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