Research reveals systematic differences in evidence-location sensitivity among models with varying long-context lengths.
An empirical study published on October 24, 2026, on arXiv (paper ID 2610.31135v1) compared the positional bias of Transformer, state-space, and hybrid Mamba architectures in long-context question-answering tasks. It found that Transformer models generally exhibit an advantage in leveraging evidence from the initial positions, whereas state-space models lack this characteristic; however, both types of models tend to favor evidence from the end positions.
Why it matters：This study, based on a controlled experimental design (with nine perturbed documents fixed and a single golden document slid), for the first time conducts a cross‑comparison of the positional sensitivity of three mainstream sequence‑modeling architectures within a unified evaluation framework. It reveals the strong coupling between model capabilities and architecture type, prompt engineering, and task characteristics, offering direct guidance for the design and tuning of long‑context AI systems.