Debiasing length preference drops a decision model from 60 to 45 on Habermas Machine

antoine_chaffin · x · 2026-10-29

The author debiased their decision model's preference for longer options, dropping it from 60 to 45 on the Habermas Machine benchmark — below the "pick the longest" heuristic (50%, vs 24% for random chance).

Key point: the model wasn't made worse; debiasing prevents it from collapsing when a few tokens are added to the wrong options. The author accepts people may ignore the model over lower benchmark scores, highlighting the tradeoff between leaderboard scores and robustness.

Related event: Researchers Warn LLM Benchmarks Skewed by Option Bias, Debiasing Can Lower Scores(3 posts)→

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