TWO years ago IBM attracted a lot of admiring publicity when its “Watson” program beat two human champions at "Jeopardy!", an American general-knowledge quiz. It was a remarkable performance. Computers have long excelled at games like chess: in 1997 Deep Blue, another of the computer giant's creations, famously beat the reigning world champion Garry Kasparov. But "Jeopardy!" relies on the ability to correlate a vast store of general knowledge with often-punny, indirect clues. Making things hardest still, the clues themselves are, famously, phrased as answers, to which contestants must supply an appropriate question.

Yet IBM has always had bigger plans for its artificial know-it-all than beating humans at quiz shows. On February 8th it announced the first of them. Together with the Memorial Sloan-Kettering Cancer Centre and Wellpoint, a health company, it plans to adapt the system for oncologists, with trials due to begin in two clinics. The idea is to use the machine as a sort of prosthetic brain for doctors, by delegating to it the task of keeping up with medical literature.

What is really impressive about Watson is not so much that it thrashes humans, but how it does so. The machine extracts “meaning” from vast quantities of what computer scientists call unstructured data, which essentially means anything designed to be consumed by humans rather than computers. To prepare for its "Jeopardy!" appearances, the program was fed (among other things) dictionaries, archives of newspaper articles, lexical databases of English and the whole of Wikipedia. From these it was able to extract relationships between concepts and become deft enough with metaphors, similes or puns that it could cope with the show’s elliptical clues.

It is this ability to process human-oriented information that IBM hopes will be useful for doctors. The volume of medical research is huge and growing. According to one estimate, to keep up with the state of the art, a doctor would have to devote 160 hours a week to perusing papers, leaving eight hours for sleep, work and, well, everything else in life. Fortunately, Watson doesn't need any sleep.

IBM's ultimate goal is for Watson—or a small computer running the front-end, since the processing itself will take place on an internet-connected supercomputer—to compare patient notes with the information harvested from medical journals, treatment guidelines, etc. It would then suggest several treatment regimens, ranked by how effective it thinks they are likely to be. Watson may even suggest clinical trials that the patient could be enrolled in.

Every one of its recommendation will be based on data in the medical literature, and the human doctor can tell the computer to show how it arrived at the conclusion, linking back to the original data. If the doctor disagrees, or wishes to add any constraints, he can tell the program by speaking into a microphone. For now, though, the plan is to use the machine for "utilisation management", American health-care jargon for deciding whether a treatment is appropriate given the state of medical knowledge—and, therefore, whether it will be paid for by an insurance company.

Ensuring that doctors can stay current with the latest developments in their field sounds like an excellent idea. And it should be easily extendable: a computer that can crunch large amounts of natural-language data has obvious uses in law, politics and academia. But having computers decide whether to grant insurance coverage already grates with some patients, a reaction that is unlikely to improve simply because IBM's new machine excels at the job. How doctors will react to the presence of an electronic clever-clogs on their desks also remains to be seen. For although no one is claiming that Watson can replace human medics, it is another instance (alongside legal work and journalism) of computers encroaching into the sorts of white-collar jobs previously thought to be the preserve of two-legged biological computers.

Correction: We originally mislabelled Memorial Sloan-Kettering Cancer Centre as a charity. It is a non-profit oncological care and research institution. Apologies.