The news: OpenAI's GPT-5.1, a notable model upgrade with improved prompt comprehension over the poorly received GPT-5, is now equipped with seven personality options.

Let’s break down how GPT 5.1 differs from its predecessor and how marketers can best use its customizable voices.

Why it matters: Two of the main problems users reported with GPT-5 were its struggles to follow instructions and stilted, stiff tone in conversations.

GPT-5.1 aims to tackle GPT-5’s woes by offering more natural dialogue, adhering more closely to parameters, having greater emotional intelligence, and being more willing to ask for clarification rather than spitballing answers.

• OpenAI stated that GPT-5.1 “Thinking” mode spends less time and fewer tokens on simple queries compared with GPT-5, giving deeper responses for complex questions while speeding up straightforward ones.
• It also uses less jargon and fewer undefined terms—an advantage for enterprise customers who want easily digestible information.

Tone options: ChatGPT’s seven personalities add a new layer of customization, letting users choose whether they want direct, mechanical responses or more creative, imaginative styles.

• Quirky and Nerdy: Enthusiastic, adjective-laden responses with plain language descriptions and easy-to-read instructions. Quirky goes heavy on emojis, and Nerdy sometimes swaps hyper-specific details for anecdotes.
• Professional, Efficient, and Candid: Similar to the “default” personality setting, with clean, simple responses and less flowery prose.
• Friendly: Warm and approachable—similar to Quirky and Nerdy but with fewer descriptors and more concise delivery.
• Cynical: More of a devil’s advocate, offering multiple angles to queries and including a bit more sass and skepticism in its responses.

Our take: Although GPT-5.1 isn’t a radical reinvention, it’s better at following instructions than GPT-5 and provides clearer conversational outputs. When paired with customizable personalities, it’s a stronger everyday tool, especially for teams that need to juggle quick-turn copy and campaign planning.

What marketers should do: Test how GPT 5.1 and the chatbot’s personalities align with specific tasks and brand tone and voice. Each GPT personality could offer unique benefits to marketer workflows and campaign development—Cynical could help evaluate pros and cons of advertising and messaging approaches, while Quirky may outperform Efficient when generating light-hearted copy for social media posts.

Agencies working with numerous brands can use the chatbot’s personalities to meet the various requirements of clients, such as Professional for more serious product campaigns—for example, a pharma or financial company—and Friendly or Quirky for Christmas campaigns from fashion brands.

This content is part of EMARKETER’s subscription Briefings, where we pair daily updates with data and analysis from forecasts and research reports. Our Briefings prepare you to start your day informed, to provide critical insights in an important meeting, and to understand the context of what’s happening in your industry. Non-clients can click here to get a demo of our full platform and coverage.