Watson is already incremental to the business, Kelly said in an interview."Incremental means it's above our base business, which are core existing businesses— all new," Mr. Kelly said. "As soon as possible, it will be very material to IBM."To attract more developers to the Watson platform, IBM is announcing new services and tools to help build applications that use cognitive computing. These moves are part of IBM's effort to sell more data-analytics and cloud-computing technology as demand for older services weaken, leading to revenue declines and divestitures. The company is also focusing on selling Watson products into areas such as education and healthcare."It's a whole new era of computing," Mr. Kelly said.