How does prior knowledge impact reading comprehension?
This is a great question. One of the great benefits of postmodernism is that it showed that there is no such thing as objective truth when it comes to reading of texts. Not only are all people different, but each person's interpretation can change through their experiences and prior knowledge.
In light of the above point, whatever a person knows will definitely change a person's reading of a text. Perhaps an example will be helpful. If a person is a reading Sophocles's Oedipus Rex as a teenager, then he or she might be repulsed by Oedipus's actions. Later on as a college student this person might read Oedipus Rex again but this time in a seminar knowing something about Greek tragedy and the historical context. This knowledge will certainly give another perspective.
And for the sake of argument, say this person reads the work again later in life, when there is an understanding of the brokenness of the world. This will give another perspective. All prior knowledge make a huge difference when it comes to reading of texts.