OpenAI has released GPT-5.1, the latest evolution of its flagship language model powering ChatGPT. The update introduces significant changes to how the AI reasons through problems and how users can customize its personality, marking a shift toward more adaptive and personalized AI interactions.
Two Modes: Instant and Thinking#
GPT-5.1 ships in two variants designed for different use cases. GPT-5.1 Instant is optimized for quick, conversational responses—ideal for everyday questions and rapid interactions. It employs adaptive reasoning to allocate computational resources efficiently, delivering fast answers to straightforward queries while dedicating more processing power when complexity demands it.
GPT-5.1 Thinking targets tasks requiring deeper analysis. This mode adjusts its processing time based on question complexity, providing clearer explanations with less jargon. For intricate problem-solving, research tasks, or detailed analysis, Thinking mode takes the time needed to deliver more thorough responses.
Adaptive Reasoning Under the Hood#
Both variants incorporate what OpenAI calls “adaptive reasoning”—the model dynamically adjusts its thinking time according to task complexity. Simple questions get quick answers; complex problems receive more computational attention. This approach aims to balance speed and thoroughness automatically, rather than forcing users to choose between fast-but-shallow or slow-but-deep responses.
Eight Personality Presets#
Perhaps the most user-facing change is the introduction of eight customizable personality modes: Default, Professional, Friendly, Candid, Quirky, Efficient, Nerdy, and Cynical. Users can switch between these presets to adjust ChatGPT’s tone and communication style to match their preferences—whether that’s a no-nonsense professional assistant or a more casual, quirky companion.
OpenAI is also experimenting with more granular customization options, including adjustable conciseness, warmth levels, and emoji usage in responses.
Rolling Out to Paid Users First#
The GPT-5.1 update is rolling out initially to paid subscribers—Pro, Plus, and Business tiers—with free users expected to gain access in the coming weeks. The release continues OpenAI’s strategy of delivering incremental improvements to its models while exploring new ways to make AI assistants feel more natural and personally tailored to individual users.