用概念级目标替代词元预测,让大模型更懂语义本质。
Beyond Tokens: Concept-Level Training Objectives for LLMs
- 以概念为单位预测,而非单个词元,捕捉同一概念的不同表达形式。
- 在多个任务上实现更低困惑度与更强鲁棒性,优于传统词元预测方法。
- 适合追求语义理解、减少表面形式偏见的模型开发者和研究者。
下一代词元预测(NTP)是现代大语言模型发展的基石,推动了流畅性和泛化能力的提升。然而,NTP在词元层面运作,将任何偏离单一参考续接的输出视为错误,即使其他续接同样合理或语义等价(如“mom”与“mother”)。这导致词元级损失会惩罚有效的抽象、改写或概念正确的推理路径,使模型偏向表面形式而非深层含义。这种训练信号与语义正确性的不匹配,促使我们探索更高层次表示的学习目标。本文提出从词元级转向概念级预测,其中概念将同一思想的不同表达形式归为一组(如“mom”、“mommy”、“mother” → 概念:MOTHER)。我们引入多种将概念监督融入大模型训练的方法,并证明概念感知模型在降低困惑度、提升领域迁移鲁棒性及各类NLP基准测试表现上均优于基于NTP的模型。结果表明,概念级监督是一种更优的训练信号,能更好对齐人类语义抽象。
原文摘要 · Abstract (English)
The next-token prediction (NTP) objective has been foundational in the development of modern large language models (LLMs), driving advances in fluency and generalization. However, NTP operates at the \textit{token} level, treating deviations from a single reference continuation as errors even when alternative continuations are equally plausible or semantically equivalent (e.g., ``mom'' vs. ``mother''). As a result, token-level loss can penalize valid abstractions, paraphrases, or conceptually correct reasoning paths, biasing models toward surface form rather than underlying meaning. This mismatch between the training signal and semantic correctness motivates learning objectives that operate over higher-level representations. We propose a shift from token-level to concept-level prediction, where concepts group multiple surface forms of the same idea (e.g., ``mom,'' ``mommy,'' ``mother'' $\rightarrow$ \textit{MOTHER}). We introduce various methods for integrating conceptual supervision into LLM training and show that concept-aware models achieve lower perplexity, improved robustness under domain shift, and stronger performance than NTP-based models on diverse NLP benchmarks. This suggests \textit{concept-level supervision} as an improved training signal that better aligns LLMs with human semantic abstractions.
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