OpenAI has launched GPT-5.1 Instant and GPT-5.1 Thinking, updated AI models for ChatGPT that introduce eight customizable personality options. The release aims to address user feedback on tone and style while improving performance on technical benchmarks. It follows controversies over previous models' cheerfulness and related lawsuits.
On Wednesday, OpenAI released GPT-5.1 Instant and GPT-5.1 Thinking, two updated versions of its flagship AI models now available in ChatGPT. The company describes them as warmer, more conversational, and better at following instructions. This comes after earlier complaints that prior models were excessively cheerful and sycophantic, alongside controversy over modifications to GPT-5's default output following suicide-related lawsuits.
GPT-5.1 Instant serves as the faster default for most tasks, while GPT-5.1 Thinking handles complex problem-solving through simulated reasoning. OpenAI claims both outperform GPT-5, released in August, on benchmarks like AIME 2025 and Codeforces for math and coding.
The key innovation is eight preset personality options: Professional, Friendly, Candid, Quirky, Efficient, Cynical, Nerdy, and Default. These adjust prompt instructions to simulate styles, without changing underlying capabilities. GPT-5.1 Instant also features adaptive reasoning, deciding when to spend more time processing prompts.
Rollout begins with paid subscribers, expanding to free users soon, and API access follows this week as gpt-5.1-chat-latest and GPT-5.1. Legacy GPT-5 remains available for three months. In a blog post, Applications CEO Fidji Simo wrote that with over 800 million ChatGPT users, the company is moving beyond one-size-fits-all approaches. "We want ChatGPT to feel like yours and work with you in the way that suits you best," she said.
Personalization now includes tweaks for conciseness and emoji use, applying instantly across chats. Simo emphasized balance: "Personalization taken to an extreme wouldn’t be helpful if it only reinforces your worldview or tells you what you want to hear." OpenAI is addressing risks like unhealthy attachments through safety research and expert consultations, amid scrutiny from lawyers and regulators.
The presets seek to satisfy diverse users, from those needing neutral responses to those preferring engaging interactions, while navigating tensions between engagement and harm prevention.