将大模型可解释性问题转化为图学习任务,提升因果电路分析的系统性。
Patch-Effect Graph Kernels for LLM Interpretability

- 用激活修补数据构建模型组件间的效应图,转为图机器学习问题。
- 局部边槽特征比全局图结构更准确区分不同任务类型。
- 提供可控基线,帮助区分可靠因果证据与表面相关性。
机制可解释性旨在通过激活修补识别因果电路,但跨多种提示和任务类型的干预会产生高维、无结构的数据,难以系统比较。本文提出将机制分析重构为图机器学习问题,将激活修补结果表示为模型组件间的补丁效应图。引入三种图构建方法:因果中介的直接影响、偏相关性和共影响,并应用图核分析其结构。在 GPT-2 Small 上评估间接宾语识别(IOI)及相关任务,发现补丁效应图能保留判别性结构信号。局部边槽特征的分类准确率高于全局图形状描述符。筛选后的配对修补验证表明,CI 和 PC 方法选出的边具有更强的激活影响效果,优于随机或低秩候选。关键的是,通过对比严格的仅提示控制和原始修补信号,明确了基准的实证范围:图特征压缩了结构化修补信号,而原始张量和表面线索构成强基线,任何电路级主张都需应对。最终框架提供了压缩与评估修补衍生结构的流水线,在受控基线下分离出可靠的切片判别证据与更具普适性的因果电路主张。
原文摘要 · Abstract (English)
Mechanistic interpretability aims to reverse-engineer transformer computations by identifying causal circuits through activation patching. However, scaling these interventions across diverse prompts and task families produces high-dimensional, unstructured datasets that are difficult to compare systematically. We propose a framework that reframes mechanistic analysis as a graph machine-learning problem by representing activation-patching profiles as patch-effect graphs over model components. We introduce three graph-construction methods: direct-influence via causal mediation, partial-correlation, and co-influence and apply graph kernels to analyze the resulting structures. Evaluating this approach on GPT-2 Small using Indirect Object Identification (IOI) and related tasks, we find that patch-effect graphs preserve discriminative structural signals. Specifically, localized edge-slot features provide higher classification accuracy than global graph-shape descriptors. A screened paired-patching validation suggests that CI and PC selected candidate edges correspond to stronger activation-influence effects than random or low-rank candidates. Crucially, by evaluating these representations against rigorous prompt-only and raw patch-effect controls, we make the evidential scope of the benchmark explicit: graph features compress structured patching signal, while raw tensors and surface cues define strong baselines that any circuit-level claim should address. Ultimately, our framework provides a compression and evaluation pipeline for comparing patching-derived structures under controlled baselines, separating robust slice-discriminative evidence from stronger task-general causal-circuit claims.
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