Qwen Model Caught Overthinking: A Simple 'Hi' Triggers Endless Reasoning Loop

nijfranck · x · 2026-08-03

A developer running the Qwen 3.5 9B model locally on a MacBook discovered that a simple "hi there" prompted an unnecessarily long and agonizing reasoning process.

The model's chain-of-thought continuously analyzed intent, drafted multiple response options, and repeatedly overrode its own decisions, stuck between "keeping it simple" and "adding warmth." The author described this severe, meaningless overthinking as "scary yet oddly human."

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