OpenAI claims ChatGPT’s new default model hallucinates way less

OpenAI released a new default model called GPT-5.5 Instant that the company claims produces fewer hallucinations (instances where an AI generates false or made-up information as if it were fact), particularly in high-stakes fields like medicine and law. According to OpenAI's internal testing, the new model generated 52.5% fewer hallucinated claims than the previous GPT-5.3 Instant model on difficult prompts.