arXiv AI

From Error Prediction to Causal Influence: Auditing SAE Features in Multiple-Choice QA

The paper investigates whether features learned by sparse autoencoders (SAEs) in multiple‑choice question answering actually influence model predictions or merely correlate with errors. Using Gemma 3 1B and 4B models across eight datasets, the authors filter out SAE features that are tied to format or content artifacts and then perform causal interventions on the remaining features. They find that while SAE activations predict wrongness and uncertainty, causal interventions on filtered features shift answer margins more than random features but rarely flip answers, suggesting the features capture context‑dependent competition rather than the root cause of mistakes.

arXiv AI
Oct 12

The Evidence Anchoring Boundary: Where Visual Interventions Matter and When They Help in Multimodal LLMs

The paper investigates how visual interventions—training‑free edits applied to multimodal large language models—affect hallucinations and prediction quality. By applying a visual‑residual edit across successive decoder layers and matching its RMS strength, the authors identify an Evidence Anchoring Boundary (EAB) where the intervention’s influence drops sharply; effects before the EAB are 13.78–26.10× larger than after it. They further compare counterfactual subtraction across different question types and introduce calibrated selective routing, which only alters predictions when calibration supports an intervention, improving attribute accuracy by 1.56–1.81 percentage points while avoiding the harms of universal subtraction.

By Qiji Zhou, Junyi Hu, Peiyu Wang, Yue Zhang
arXiv AI
Oct 9

RAG-Stress: Probing the Limits of Evidence Reliance in Retrieval-Augmented Generation

The paper introduces RAG‑Stress, a diagnostic protocol that tests how retrieval‑augmented generation models handle misleading evidence. By fixing the question and reference answer, editing a single assertion to support an incorrect answer, and varying source‑priority policies and evidence positions, the study measures misleading rate (MR) and clean accuracy across fifteen systems on multiple QA datasets. Results show that prioritizing documents increases MR by 10.9–13.5 percentage points, with the highest MR when the misleading span appears at the end of the evidence.

By Shunyuan Zhou, Hao Chen, Tianyu Wang, Goose Lin, Zaiyuan Wang, Haiying Zhao
arXiv Computation and Language
Oct 5

Understanding Why Language Models Hallucinate: Testing Reasoning Against Priors

The paper investigates why large language models hallucinate by proposing that failures often stem from inference misalignment rather than missing knowledge. It introduces a latent key-task model that shows pretraining-frequency imbalance can cause shortcut inference paths to dominate, leading to hallucinations. The authors create TrapQA, a diagnostic testbed with ScientistQA and Real-Life Constrained QA, to demonstrate two failure modes—task-retrieval bias and key-selection bias—where biased latent inference produces hallucinated answers.

By Yangfan Hu, Xuhan Tong, Haoyue Bai, Xi Ding, Shashank Muralidhar Bharadwaj, Siyang Cao, Robert Nowak, Jiawei Zhang