# EP 42: What Is GPT-5.1? Instant, Thinking and 8 Personalities Explained - URL: https://www.agenticpod.net/episodes/ep42-gpt-5-1-instant-thinking/ - Watch on YouTube: https://www.youtube.com/watch?v=pdn6ZQWP-js - Published: 2026-11-13 - Length: 5 min - Hosts: Stella (asks), Liam (answers). Both are AI hosts with AI-generated voices. ## Summary OpenAI released GPT-5.1 on November 12, 2026, as an upgrade inside the GPT-5 generation, with Instant, Thinking, Auto routing and 8 personality presets. ## Key takeaways - GPT-5.1 is an upgrade inside the GPT-5 generation, not a new generation: Instant for everyday questions, Thinking for harder reasoning, and Auto routing each question to the model that fits it best. - Instant is warmer and more conversational by default, better at following instructions, and now uses adaptive reasoning, deciding when to think before it answers. - Thinking adapts its time more precisely: roughly 2 times faster than GPT-5 Thinking on the fastest tasks and 2 times slower on the slowest, with clearer answers and less jargon. - There are 8 personality presets: Default, Professional, Friendly, Candid, Quirky, Efficient, Nerdy and Cynical. Professional, Candid and Quirky are new, and the rest include renames like Efficient for Robot. ## Chapters - 0:00 Intro - 0:45 Two models and Auto picks for you - 1:32 Instant got warmer and learned when to think - 2:18 Thinking spends time where it counts - 3:04 8 personalities, rollout and the honest verdict ## FAQ **What is GPT-5.1?** An upgrade inside the GPT-5 generation, released November 12, 2026, with 2 models in ChatGPT (Instant and Thinking), Auto routing, adaptive reasoning, and 8 personality presets. **What is the difference between GPT-5.1 Instant and Thinking?** Instant is the everyday model, warmer and better at following instructions, now deciding when to think. Thinking is for harder reasoning and adapts its thinking time, roughly 2 times faster on the fastest tasks and 2 times slower on the slowest. **Which GPT-5.1 personality should I use?** Pick per use: Efficient for work summaries, Candid for direct advice, Professional for anything a client will read. Settings apply instantly across all chats. **When does GPT-5.1 reach the API?** Later in the launch week: gpt-5.1-chat-latest for Instant, gpt-5.1 for Thinking, plus gpt-5.1-codex and gpt-5.1-codex-mini for long running agentic coding. ## Resources - [Step-by-step guide](https://github.com/asly-97/ai-automation-workflows/tree/main/gpt-5-1-instant-thinking) - [OpenAI GPT-5.1, what changed](https://technewsnest.com/openai-gpt-5-1-what-changed/) ## Transcript ### Intro Liam: Hey hey hey, welcome to Agentic Pod! I'm Liam. Stella: And I'm Stella! Liam, OpenAI released GPT-5.1 on November 12th, and it now comes with 8 personalities? Liam: 8, yeah. And 2 models under one name. GPT-5.1 Instant for everyday questions, and GPT-5.1 Thinking for harder reasoning. Stella: So which one do I actually get when I open ChatGPT? Liam: That is the trick. Most people meet GPT-5.1 Auto first, and Auto picks for you. By the end you will know which model does what, and which personality to pick. ### Two models and Auto picks for you Stella: Okay, basics. Is GPT-5.1 a whole new generation? Liam: No. It is an upgrade inside the GPT-5 generation, not a new generation. Same family, sharper manners. Stella: Sharper manners is one way to sell a software update. Liam: Fair. There are 2 models in ChatGPT. Instant is the most used model, for everyday questions. Thinking is for harder reasoning work. Stella: And Auto? Liam: GPT-5.1 Auto routes each question to the model that fits it best. Quick question, quick model. Hard problem, more thinking. Stella: So Auto is like a receptionist who decides if you need a sprint or a marathon. Liam: Exactly. And that routing matters, because Instant itself changed a lot this time. That is next. ### Instant got warmer and learned when to think Liam: Instant is warmer by default now, and more conversational. OpenAI says early testers noted it stays playful while staying clear and useful. Stella: Playful but useful. Like you on a good day. Liam: I will take that. Instant is also better at following instructions, which is the part I actually care about. Stella: Same. What is the big technical change? Liam: Adaptive reasoning. Instant now decides when to think before it answers. Simple prompt, fast answer. Tricky prompt, it pauses and thinks first. Stella: So it does not burn the same effort on what is 2 plus 2 and on a planning problem? Liam: Right, right. That split should make daily work feel snappier. But for the really hard stuff, you want the other model. ### Thinking spends time where it counts Stella: Okay, Thinking. How is it different from the old GPT-5 Thinking? Liam: It adapts its thinking time more precisely. On the fastest tasks it is roughly 2 times faster than GPT-5 Thinking. On the slowest tasks it is roughly 2 times slower, because it thinks longer. Stella: Faster when it can be, slower when it should be. That sounds obvious, but models are bad at it. Liam: They are. Thinking also gives clearer answers, with less jargon and fewer undefined terms. Stella: Less jargon is a real feature. I say that as your full time translator. Liam: And the default tone is warmer and more empathetic too. So both models got the manners upgrade, Thinking just gets the time budget. Stella: Good. Now the part everyone will play with first. The personalities. ### 8 personalities, rollout and the honest verdict Liam: 8 presets total. Default, Professional, Friendly, Candid, Quirky, Efficient, Nerdy, and Cynical. Stella: 8. Which ones are actually new? Liam: 3 are new: Professional, Candid, and Quirky. The rest are renames. Friendly was Listener, Efficient was Robot, Cynical was Cynic, and Nerdy was Nerd. Stella: Robot to Efficient is the most honest rebrand I have ever heard. Liam: Settings apply instantly across all chats. And there is more tuning coming. Conciseness, warmth, scannability, and emoji frequency, rolling out gradually as an experiment to a limited number of users later this week. Stella: Who gets GPT-5.1 first? Liam: Rollout began November 12, starting with paid users on Pro, Plus, Go, and Business. Free and logged out users follow gradually over the next few days. Stella: And schools and companies? Liam: Enterprise and Education get a 1 week early access preview before GPT-5.1 becomes the default. GPT-5 stays for paid users for 3 months in a dropdown. GPT-5 Pro becomes GPT-5.1 Pro soon, no date given. Stella: And for builders? Liam: API comes later the same week. Instant as gpt-5.1-chat-latest, Thinking as gpt-5.1, both with adaptive reasoning. Plus gpt-5.1-codex and gpt-5.1-codex-mini for long running agentic coding. Stella: Okay, honest verdict. No vibes, your rule. Liam: Try Instant for daily work. Route hard, multi step work to Thinking. Measure instruction following on your own tasks, not on a demo. Stella: And personalities are not a toy if you pick with intent, right? Liam: Right. Efficient for work summaries. Candid for direct advice. Pick per use, and do not judge any of it by tokens or vibes. Stella: Same. The step by step guide is in the description. Which personality would you actually use every day, Efficient or Candid? Tell us in the comments. See you next time!