Deconstructing Overconfident Failures in Code LLMs: Instruction Tuning Inflates Confidence on Failing Code
Researchers have conducted the first systematic empirical study characterizing overconfident failures in code LLMs across HumanEval+, MBPP+, and BigCodeBench. Analyzing CodeLlama, DeepSeek-Coder, Qwen2.5-Coder, and OpenCoder, the paper reveals that instruction tuning significantly inflates confidence on erroneous code without improving discrimination between correct and failing programs.
- •Disconnect between confidence and execution correctness: erroneous programs exhibit token- and program-level confidence comparable to correct code
- •Side effects of instruction tuning: post-training inflates certainty on failing generations without improving discriminative calibration
- •Latent representations hold hidden signals: exploratory internal state probing shows hidden layers encode correctness indicators suppressed at the output level
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