I think it is just choosing words and matching them with what a particular author may typically use. My first paragraph had the word 'demon' and it chose Anne Rice. My second paragraph talked of carriages so I got Arthur Conan Doyle. My last choice got Neil Gaiman. I haven't worked out why yet. All are paragraphs from a story I wrote. I guess I should be pleased that they are all good authors but wow, what a variety.