arXiv Computation and Language By Ziyuan Wang, Genliang Zhu, Xiaobo Chen

Do Multimodal Models Decide Consistently on Equivalent Optical Spectra?

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The study evaluates whether multimodal models produce consistent decisions when presented with equivalent optical spectra in different representations—tables in nanometers, micrometers, scientific notation, or photon energy, and plots in wavelength or energy. Using datasets of silicon metasurfaces and gold nanoparticles, the authors test several models (d3-nano, Jev 1.13, GPT‑6 Luna variants, Qwen3.5‑2B) and find that representation changes can shift accuracy by up to 41 percentage points, with some models benefiting from photon‑energy inputs while others suffer. Fine‑tuning with LoRA improves performance on trained formats but often relies on a shortcut of abstaining when data are truncated; training with answerable truncations mitigates this shortcut, revealing significant gaps in models’ handling of missing evidence.

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