The short answer is that we don't really know what we think we know. I've written about false memories before a couple of times, most recently in my February Book of the Month post, and now we have an almost textbook example of it in NBC's Brian Williams.
His story illustrates almost perfectly how a false memory can be planted, watered, nurtured, and allowed to come to full bloom. It's pretty easy to dismiss Williams as a lying liar warrior-wannabe and an example of "big media" and its lying liars who lie, but I don't think it's as simple as that.
There's an excellent article at rival network CBS called Brian Williams and the false memory phenomenon" that is worth taking a look at:
"I was kind of amazed by how insistent and quick people would say he was liar when there was another plausible interpretation -- that he had a false memory," Elizabeth Loftus, a distinguished professor the at the University of California, Irvine, and an expert in human memory, told CBS News. "Mostly these false memories develop and people are not even aware of why they happen."How many times has something like this happened to you: Two people who were both at the same incident will talk about it later and realize that they disagree on the details so radically that an independent observer will come away thinking that they were witness to two different incidents?
Loftus calls Williams' circumstances a "teaching moment." She says it's a perfect example of how a false memory can subconsciously slide into a person's psyche until it becomes their version of the truth. Williams defines his mess-up as a the "fog of memory."
Loftus explains that a false memory occurs when a person comes to believe something happened that didn't; they may have adopted an account they heard or made up, perhaps based on details that are distorted and loosely based on the truth. "Brian Williams is sort of a combination of this," says Loftus.
This kind of thing happens between me and She-Who-Must-Be-Obeyed all the time. It makes for some interesting ... "discussions".
It's a phenomenon that should be more well known, which is why so-called "eyewitness testimony", while it has a lot of seeming credibility in a courtroom, is the most unreliable testimony. And yet people are routinely sentenced to death because of it.
And of course, Jon Stewart has his own unique take on the whole Brian Williams saga.