The "myside bias," defined as a bias against information supporting another side of an argument (Perkins 1985;Wolfe, Britt, and Butler 2009), can be observed by the presence of rebuttals to the author's claim or by formulating arguments for both sides when the overall stance is neutral.
85% of the documents do not consider any opposing side, and only 8% of the documents present a rebuttal, which is then attacked by refutation in 4% of the documents.