bigger-or-cheaper-scale-and-quantization-effects-on-uncertainty-signals-in-vision-language-models-under-image-degradation-3b35eb0f·1 events·first seen Aliases: Bigger or Cheaper? Scale and Quantization Effects on Uncertainty Signals in Vision-Language Models Under Image Degradation
A new arXiv paper evaluates how model scale and 4-bit quantization affect two confidence signals — verbalized confidence and mean token probability — in the Qwen2-VL family across 5,700 predictions under six photographic degradation types. Key findings: scaling from 2B to 7B sharply improves internal uncertainty (AUROC 0.80→0.98) while verbalized confidence remains weak; 4-bit quantization costs little in accuracy (-1.6 pts) but degrades the internal confidence signal (AUROC 0.95→0.80) and collapses verbalized-confidence parse rate from 99% to 64%. The practical recommendation is to prefer a larger quantized model over a smaller full-precision one within a fixed memory budget, and to use error-detection AUROC rather than calibration error as the primary metric.