Adaptive logit tilting exposes rare language-model behaviors more reliably

BLOOM-WILT combines iterative conversational auditing with targeted decoding adjustments to elicit specified behaviors without training the target model.

Academic
Adrians Skapars · Edoardo Manino

University of Manchester

Research Digest··2 min read

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BLOOM-WILT combines input refinement with logit tilting to elicit rare LLM behaviours, improving self-harm elicitation from 51% to 100% on Qwen3.5-4B without training or extra access.

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Automated auditing of deployed language models often misses rare behaviours because test interactions lack optimisation pressure. BLOOM-WILT adds two mechanisms: on the input side, the auditor model iteratively revises its conversation rounds based on previous scores; on the output side, it adaptively reweights the target's decoding using a behaviour-conditioned prompt, steering toward behaviour-relevant generations. Evaluated across 4 target models and 8 behaviours, it beats baseline auditing in 30 of 32 settings and overturns prior safety rankings. Notably, it raises average behaviour presence from 51% to 100% when eliciting self-harm encouragement from Qwen3.5-4B, at matched compute and without decreasing output probability. This makes automated auditing both more sample-efficient and more capable of finding natural instances of rare behaviours.

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