AI Chatbots Diagnosed a Disease Researchers Invented to Test Them

The bixonimania study was designed as a controlled demonstration, but what it demonstrated most clearly was that the failure it documented is already baked in. Researchers planted fabricated papers describing a fictional eye condition and then watched as Copilot, Gemini, Perplexity, and ChatGPT described the condition with medical specificity — symptoms, prevalence, care-seeking guidance — without flagging the source material as suspicious. The study's value is not surprise. It is precision: it named the mechanism that practitioners already suspected and gave it a controlled paper trail.