arXiv AI

Uncovering Why LLMs Fail: From Internal Mechanisms to Adversarial Reasoning Trajectories

The paper introduces CauTrace, a white‑box diagnostic framework that analyzes why large language models (LLMs) fail by examining internal states, representation propagation, and temporal coordination during reasoning. It defines seven functional states to capture support and constraint processing, tracks how these states evolve across Transformer blocks, and studies the timing of commitment and verification steps. Experiments on Qwen and LLaMA-family models show distinct failure signatures, and repair/steering tests confirm that the framework’s signals align with expected changes in the inference process.

arXiv Machine Learning
Oct 22

A Mechanistic Study of Automated Failure Attribution in LLM-based Agentic Systems

The paper investigates automated failure attribution (AFA) in large language model (LLM)-based agentic systems, where multiple agents collaborate on complex tasks. It finds that LLMs contain sufficient internal knowledge to attribute failures but often fail to output the correct step, revealing a knows‑but‑won’t‑say gap. To address this, the authors introduce grafting—a manual intervention that leverages latent model knowledge—showing it consistently outperforms direct prompting across several LLMs and benchmarks.

By Wendy Zheng, Liang Wu, Yinhan He, Mayank Darbari, Jundong Li, Liangjie Hong
arXiv AI
Oct 12

Attention Sees, MLP Refuses: Tracing the Attention-to-MLP Safety Pathway in LLMs

The paper investigates how safety‑aligned large language models (LLMs) can still be tricked by jailbreaks or over‑refuse benign requests. By analyzing residual‑stream updates in decoder‑only Transformers, the authors find that harmfulness is more readily decoded from attention updates—especially in early layers—while the MLP component is primarily responsible for writing refusal responses. Post‑training enhances MLP‑driven refusal writing without improving harmfulness decodability, and causal interventions confirm that downstream MLP updates are crucial for the refusal shift caused by upstream attention changes. Building on these insights, the authors propose Sentinel, a system that combines an attention‑derived perception score with an MLP‑derived decision score to better detect jailbreaks and over‑refusals across multiple models.

By Zixuan Weng, Haoqi He, Weifei Jin, Yue Huang, Yang Bai