arXiv:2506.16288cs.LGcs.AI2025-06

让模型根据模糊程度调整预测策略,提升复杂场景下的生成质量

Next-Token Prediction Should be Ambiguity-Sensitive: A Meta-Learning Perspective

  • 用元学习构建可控制模糊度的合成数据集,测试模型表现
  • 发现大模型在高模糊情境下预测能力显著下降
  • 提出蒙特卡洛推理框架,实现灵活的生成与高效推断

自回归基础模型的快速适应能力通常归因于预训练数据的多样性。从贝叶斯视角看,最小化预测误差需对所有与观测一致的潜在假设进行积分。然而,在高模糊性情况下,可行假设数量庞大,贝叶斯最优预测变得计算不可行。认知科学认为此时应采用启发式或信息获取策略。我们据此提出:低与高模糊性预测应有不同的计算需求,而当前普遍的模糊无关预测是一种有害的归纳偏置。为此,我们设计了具有丰富组合结构和可计算贝叶斯真值的合成元学习基准MetaHMM。实验表明,不同规模的Transformer在高模糊任务中均表现不佳。受认知理论启发,我们提出将预训练模型转化为蒙特卡洛预测器的方法,实现任务推断与词元预测解耦。初步结果表明,该方法在模糊情境下通过更优的资源分配与可扩展的测试时推断,显著提升了性能,但仍有挑战待解决。

原文摘要 · Abstract (English)

The rapid adaptation ability of auto-regressive foundation models is often attributed to the diversity of their pre-training data. This is because, from a Bayesian standpoint, minimizing prediction error in such settings requires integrating over all plausible latent hypotheses consistent with observations. While this behavior is desirable in principle, it often proves too ambitious in practice: under high ambiguity, the number of plausible latent alternatives makes Bayes-optimal prediction computationally intractable. Cognitive science has long recognized this limitation, suggesting that under such conditions, heuristics or information-seeking strategies are preferable to exhaustive inference. Translating this insight to next-token prediction, we hypothesize that low- and high-ambiguity predictions pose different computational demands, making ambiguity-agnostic next-token prediction a detrimental inductive bias. To test this, we introduce MetaHMM, a synthetic sequence meta-learning benchmark with rich compositional structure and a tractable Bayesian oracle. We show that Transformers indeed struggle with high-ambiguity predictions across model sizes. Motivated by cognitive theories, we propose a method to convert pre-trained models into Monte Carlo predictors that decouple task inference from token prediction. Preliminary results show substantial gains in ambiguous contexts through improved capacity allocation and test-time scalable inference, though challenges remain.

语言建模贝叶斯推理元学习

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