ChatGPT update rolls out GPT-5.5 Instant with fewer hallucinations and more personalized answers
52.5% fewer hallucinations. OpenAI just made ChatGPT's default model actually safer for high-stakes decisions.
Why it matters
OpenAI is shipping tangible safety improvements (hallucination reduction on medical/legal topics) and personalization features to all ChatGPT users, signaling a shift from raw capability races to deployment-grade reliability—a competitive move that changes what 'production-ready' means for enterprise AI adoption.
The key facts
6 to knowGPT-5.5 Instant becomes default ChatGPT model
52.5% reduction in hallucinations on high-risk topics (medicine, law) in internal testing
New 'memory sources' feature shows which stored context shaped responses
Rollout to all ChatGPT users immediately
Personalization (past chats, files, Gmail integration) launches first for Plus/Pro users on web
Feature addresses critical pain point: hallucination risk in regulated/high-stakes domains
Go to the source
The Decoderthe-decoder.com
Publisher excerpt: OpenAI is swapping out ChatGPT's default model for GPT-5.5 Instant. In internal testing, the update produced 52.5 percent fewer hallucinated claims on high-risk topics like medicine and law. A new feature called "memory sources" lets users see which stored context shaped a given response. The model…