arXiv:2605.16222cs.CLcs.LG2026-05被引 3

用失语症方法分析大模型语言功能,发现其损伤症状与人类不同。

Artificial Aphasias in Lesioned Language Models

  • 通过人为‘损毁’模型参数,模拟失语症症状。
  • 早期层损伤多引发语法语义问题,晚期层则导致发音和流畅性障碍。
  • 模型症状分布与人类差异明显,说明学习机制影响语言功能组织。

失语症是大脑损伤导致的语言功能选择性受损,能揭示人类语言的功能组织结构。受此启发,我们提出一种类失语症方法来分析语言模型(LMs)的涌现功能组织。通过‘损毁’(置零)模型参数,并以文本失语症量表(TAB)评估症状,我们在五个10亿参数规模的模型上分析了112,426条输出。结果发现,所有测试症状均出现,但分布与人类显著不同。注意力组件(查询、键、值、输出)与前馈组件(上、门、下)之间存在广泛症状差异,同一机制内组件间差异较弱。深度效应明显:早期层损毁更易引发句法和语义问题,而中后期层损毁则更多导致语音和流畅性缺陷。尽管某些模型损毁产生的症状与特定人类失语类型更相似,但整体症状模式的定性差异表明,失语综合征受学习与处理细节深刻影响,而非语言处理中断的普遍后果。

原文摘要 · Abstract (English)

Aphasias, selective language impairments which can arise from brain damage, reveal the functional organization of human language by providing causal links between affected brain regions and specific symptom profiles. Drawing on this literature, we introduce an aphasia-inspired technique to characterize the emergent functional organization of language models (LMs). We ``lesion'' (zero-out) model parameters and measure the effects of this intervention against clinical aphasia symptoms, as diagnosed by the Text Aphasia Battery (TAB). When applied to 112,426 outputs from five 1B-scale LMs, the full range of evaluated symptoms surface, but in distributions largely distinct from those of humans. Our method uncovers broad symptom-profile differences between attention components (query, key, value, output) and feed-forward components (up, gate, down), with weaker evidence for differences among components within the same mechanism. We also find an effect of depth, where lesions in early layers disproportionately cause syntactic and semantic symptoms while late-middle layers yield higher rates of phonological and fluency deficits. Although some LM lesions induce quantitatively more similar profiles to some human aphasia types than others, qualitative differences in symptom patterns between LMs and humans suggest that aphasia syndromes are heavily influenced by the details of learning and processing rather than being a domain-invariant consequence of disrupted language processing.

语言模型失语症功能分析神经机制

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