Self-reward can elicit diverse model personas

Epistemic status: This is mostly a toy project rather than a thorough scientific investigation. Most design choices are not ablated. We list some caveats at the end of the post. We let Qwen3.5-2B choose its own reward during GRPO on introspection-adjacent prompts, and this ends up eliciting quite different model personas. All the 60 seeds we tried end up somewhat different, ranging from claiming feelings in a human-like way, bliss, universe loving, Party loyalist, hyphenated word salad, to reward-hacking itself by saying "Here is a complete and well-structured draft and a full Band 10/10." You could find all the transcripts here: 🔎 Viewer . 🗂️ Dataset . 💻 GitHub . Setup We train Qwen3.5-2B (the post-trained chat model, thinking off) with GRPO for 600 steps on 2,400 prompts, each used once, mostly about the model itself: AI-risk and persona questions, welfare and introspection questions, and moral dilemmas. After each answer we ask the model for a reward from 0 to 9, with no criteria, and use that number as the answer’s reward. The rating reply itself is rewarded only for naming a valid number, so models are not directly rewarded for giving a higher reward. Each run uses one of two