ChatGPT Upgrades to GPT-5.5 Instant: Fewer Hallucinations

OpenAI has upgraded ChatGPT's core engine, rolling out GPT-5.5 Instant as the new default model. This change promises fewer made-up answers. Here's the thing: OpenAI claims a 52.5% drop in "hallucinations" for critical topics like medicine and law. This means you should get more reliable information. What's interesting is a new "Memory Sources" feature. It shows you what ChatGPT remembers from past chats and lets you delete that information, giving you more control over your data. The rollout started on May 5th, 2026, and replaces the older GPT-5.3 Instant. OpenAI also says answers will be shorter and more concise. This upgrade aims to make ChatGPT a more trustworthy and transparent tool for everyone.