I think when it comes to determining what form of literature individuals enjoy reading, I don't think you really need science to figure this one out. Just simply pole as many Americans as possible and have their explain what kind of literature they like to read. People like to read what they find interesting.
Science can study your brain and the activity that goes on inside of it when you are reading certain literature. This information can then be used to determine what kind of literature triggers your brain in a certain way. If you like to read that literature, then it will show up in the study.
Science probably won't be able to predict what type of literature people would like to read. While we could run it all through algorithms for book suggestions, similar to what a giant retail website does, the recommendations are often way off. "Likes" are very subjective, and just because someone enjoys one type of book, it doesn't mean that a similar one will also be enjoyable to him or her. Tastes are far too subjective for science.
Science can examine many things in the physical world but it can not answer everything. It can not deal with realities that might not be on the physical level and so can not be seen or experienced with the senses. It can not tell us what kind of literature someone reads or what kind of music he or she will enjoy.
Science cannot determine what kind of literature individuals like to read. Science is amazing but I highly doubt that they will be able to succeed in this one. Individuals choose what they like to read and it is a personal choice so I highly doubt they will find a way to predict this. Also, what would be the point, is this not a waste of resources?