Pollyanna is a best-selling 1913 novel by Eleanor H. Porter that is now considered a classic of children's literature, with the title character's name becoming a popular term for someone with the same very optimistic outlook. Also, the subconscious bias towards the positive is often described as the Pollyanna principle. The book was such a success that Porter soon produced a sequel, Pollyanna Grows Up (1915). Eleven more Pollyanna sequels, known as "Glad Books", were later published, most of them written by Elizabeth Borton or Harriet Lummis Smith. Further sequels followed, including Pollyanna Plays the Game by Colleen L. Reece, published in 1997. Pollyanna has been adapted for film several times. Some of the best known are Disney's 1960 version starring child actress Hayley Mills, who won a special Oscar for the role, and the 1920 version starring Mary Pickford.