让语言模型与世界模型分离,提升生成的逻辑性和可控性。
The Mouth is Not the Brain: Bridging Energy-Based World Models and Language Generation
- 用能量模型构建世界认知,语言模型仅负责表达。
- 生成文本更连贯,对价格品牌组合的判断更合理。
- 可精准干预属性并影响输出,适合需要可控生成的场景
大型语言模型(LLMs)能生成流畅文本,但其是否真正理解世界仍存争议。本文提出‘嘴不是脑’架构原则,明确分离世界模型与语言模型。系统包含:基于能量的深度玻尔兹曼机(DBM)作为世界模型,捕捉领域结构;适配器将隐含信念状态映射到嵌入空间;冻结的GPT-2提供语言能力但无领域知识。在亚马逊手机评论数据集上验证,结果表明:(1) 世界模型条件化显著降低交叉熵损失,提升语义相似度,且软提示克服了简单提示表达力不足与详细提示导致小模型输出崩溃的矛盾;(2) DBM的能量函数能区分合理与不合理市场配置,对不合理的品牌-价格组合赋予更高能量;(3) 对特定属性的干预可因果传递至生成文本,干预后输出分布统计上与真实样本一致。这表明即使小型语言模型,只要连接合适的外部世界模型,也能实现稳定、可控的生成,为语言能力与世界理解分离提供了实证支持。
原文摘要 · Abstract (English)
Large Language Models (LLMs) generate fluent text, yet whether they truly understand the world or merely produce plausible texts about it remains contested. We propose an architectural principle, the mouth is not the brain, that explicitly separates world models from language models. Our architecture comprises three components: a DBM that captures domain structure as an energy-based world model, an adapter that projects latent belief states into embedding space, and a frozen GPT-2 that provides linguistic competence without domain knowledge. We instantiate this framework in the consumer review domain using Amazon smartphone reviews. Experiments demonstrate that (1) world model conditioning achieves lower cross-entropy loss and higher semantic similarity than architectural baselines including direct projection and full fine-tuning, while qualitative analysis reveals that soft prompt conditioning resolves a trade-off that prompt-based approaches cannot: simple prompts lack expressiveness while detailed prompts cause output collapse in small LLMs; (2) the DBM's energy function distinguishes coherent from incoherent market configurations, assigning higher energy to implausible brand-price combinations; and (3) interventions on specific attributes propagate causally to generated text with intervened outputs exhibiting distributions statistically consistent with naturally occurring samples sharing the target configuration. These findings suggest that even small-scale language models can achieve consistent, controllable generation when connected to an appropriate world model, providing empirical support for separating linguistic competence from world understanding.
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