A while ago I listened to some lectures to learn a bit about neurology. One topic that came up was Source Amnesia. This describes a human tendency to remember things like statements and facts, but not the context in which one heard them and the caveats, explicit or not, that came with the statement.
Here is the same Sam Wang in the NYT.

I had no picture, so why not something a little less heteronormative than the usual random picture choice (From the classy but very NSFW Jess Fink)
“The brain does not simply gather and stockpile information as a computer’s hard drive does. Facts are stored first in the hippocampus, a structure deep in the brain about the size and shape of a fat man’s curled pinkie finger. But the information does not rest there. Every time we recall it, our brain writes it down again, and during this re-storage, it is also reprocessed. In time, the fact is gradually transferred to the cerebral cortex and is separated from the context in which it was originally learned. For example, you know that the capital of California is Sacramento, but you probably don’t remember how you learned it.
This phenomenon, known as source amnesia, can also lead people to forget whether a statement is true. Even when a lie is presented with a disclaimer, people often later remember it as true.
With time, this misremembering gets worse. A false statement from a noncredible source that is at first not believed can gain credibility during the months it takes to reprocess memories from short-term hippocampal storage to longer-term cortical storage. As the source is forgotten, the message and its implications gain strength.”
The article, and this one on the same topic go on to describe the problem in light of political rumours (especially the Obama = secret muslim rumours that were present in the then presidential race) and how the patently false can become entrenched in many heads. They also describe the role of repetition in enforcing beliefs, as it is (unconciously) interpreted as evidence that the belief is widespread.
This has many alarming implications, especially for political media coverage and public debate.
It makes any media bias that exists more troubling. I used to be comforted by the fact that while there was little respect for truth or intellectual honesty in Australian media, particularly in the dominant player (News Ltd), I had no reason to expect that most media consumers were any more credulous or passive than I. After all, they report an opinion of media ethics that is very low. I also think the idea that everyone is is credulous is misanthropic. But it turns out that it doesn’t matter. Skepticism of a source is no use when you forget it. Bullshit oft repeated, whether in the form of dishonest bias or just bad fact checking, is dangerous even when people are sensible and skeptical.
The effects of bad media habits are amplified. Framing any announcement as a conflict (inventing opposition if needed); the industry standard of treating rent seekers and PR spivs as content providers; using weasel words and reverse ferrets to publish statements that are unverified or demonstrably false etc.. All potentially more dangerous than I thought. It doesn’t help that the journalists are prone to the same amnesia, which might be why an opinion can quickly solidify into the kind of groupthink Ken Parish criticized earlier, which can then be transferred to consumers. (Continued)