Contextual Searchlight via PMI

Variance-Calibrated Modulation (VCM): training-free decoding intervention to address LLM likelihood trap

Researchers propose Variance-Calibrated Modulation (VCM), a training-free pre-decoding method that reshapes LLM probability distributions before truncation to combat repetitive degeneration and vocabulary dullness. VCM combines two mechanisms: Contextual Searchlight via PMI (suppressing stopwords, elevating context-relevant tokens) and Adaptive Self-Debiasing (scale-invariant penalization using real-time logit standard deviation). Evaluated across open-ended generation, factual QA, and mathematical reasoning, VCM improves diversity, coherence, and reasoning accuracy at higher temperatures with negligible overhead. The method is compatible with existing decoding strategies like Top-p and Min-p.