Researchers trying to improve health care with artificial intelligence usually subject their algorithms to a form of machine med school. Software learns from doctors by digesting thousands or millions of x-rays or other data labeled by expert humans until it can accurately flag suspect moles or lungs showing signs of COVID-19 by itself. A study published this month took a different approach—training algorithms to read knee x-rays for arthritis by using patients as the AI arbiters of truth instead of doctors. The results revealed that radiologists may have literal blind spots when it comes to reading Black patients' x-rays. Ziad Obermeyer, an author of the study and a professor at the University of California Berkeley's School of Public Health, was inspired to use AI to probe what radiologists weren't seeing by a medical puzzle.