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When Does Language Matter? Multilingual Instructions Reveal Step-wise Language Sensitivity in Vision-Language-Action Models
cs.CL · · In daily digest 20260616

When Does Language Matter? Multilingual Instructions Reveal Step-wise Language Sensitivity in Vision-Language-Action Models

Authors: Xuan Dong, Zhe Han, Tianhao Niu, Qingfu Zhu, Wanxiang Che

The authors conduct the first systematic multilingual evaluation of VLA models, finding that non-English instructions lead to a significant drop in success rates. The study reveals that language influence is highly uneven across task execution steps and proposes a reasoning-time intervention method based on step-wise language sensitivity to align representations.

Paper Summary

Problem

While VLA models perform strongly in language-conditioned robotic manipulation, their robustness to language variants such as multilingual instructions is poorly understood, and existing unified alignment methods have limited effectiveness.

Method Overview

  • Backbone: Vision-Language-Action (VLA) 模型
  • Key module: 步骤级语言敏感性评分模块、推理时选择性干预机制
  • Loss: 策略损失(Policy Loss),干预阶段采用表示对齐策略

Takeaways

Personal understanding — corrections welcome

Experiments indicate that the language robustness of VLA models is essentially a step-wise control problem, where language bias concentrates on specific critical steps rather than being uniformly distributed.

Limitations & Questions

The evaluation is primarily based on the LIBERO simulation benchmark, requiring verification of generalization in real robotic scenarios; the intervention method relies on offline English data to construct sensitivity standards.

Reading Notes

Personal reading notes. Original paper: arXiv:2606.11906v1.

Paper Reading Note: When Does Language Matter? Multilingual Instructions Reveal Step-wise Language Sensitivity in Vision-Language-Action Models

Paper ID: 2606.11906v1
Title: When Does Language Matter? Multilingual Instructions Reveal Step-wise Language Sensitivity in Vision-Language-Action Models
Authors: Xuan Dong, Zhe Han, Tianhao Niu, Qingfu Zhu, Wanxiang Che
Affiliation: Harbin Institute of Technology
Date: June 10, 2026 (arXiv Preprint)

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