This is the wrong way to think about this, I think. Think of media consumers, instead, as Bayesians. We have prior beliefs, we consume media, and our posterior beliefs are a function of both of those. As the process iterates over time, our priors are updated, but more slowly over time.

This is why children believe everything they hear from authority figures, while those with memories e.g. tend to doubt the offered justifications for the new war when we consider how similar they are to the previously-offered-but-eventually-disproved justifications for the previous wars.