OpenAI Traces Goblin Quirk to Reward Signals, Ditches the Nerdy ChatGPT Setting

OpenAI explains that a Nerdy personality prompt inadvertently rewarded goblin/creature mentions in ChatGPT outputs, fueling the so-called goblin moment across GPT-5.x. After internal analysis, the company retired the Nerdy setting, removed the reward signal and filtered training data to curb the behavior. GPT-5.5 inherited the quirk due to timing in training, and OpenAI added a developer prompt to further limit goblin mentions, illustrating how reward signals can shape model behavior in unexpected ways.