I think it is more fallible than you imagine.
OK, here's just one thing to consider:
http://en.wikipedia.org/wiki/Memory_implantation
Now, probably nobody intentionally implanted a false memory in Brian Williams, but we also know that these things can easily happen naturally as well.
How do you know that your memories are correct?
This is a complicated question, and I've thought about it. It's really hard to give a pithy answer. I'm aware of those studies.
Basically, you remember what you attended to and believed at the time, and told yourself at the time, and afterward. Not so much sensory details.
If you constantly tell a story to be entertaining -- say, in a bar to your pals -- it will start to acquire distortions stemming from your desire to be entertaining. This can be accounted for.
The way you know whether your memories are basically accurate is by confirmation with recorded media and by other people, and by understanding your own motives.
Another way is by attending to what was utterly novel at the time. Genuine memories often don't particularly add to the shape of the narrative.
Example: When I was abducted at gunpoint by a child molester, he had
Band of Gypsies by Jimi Hendrix on his turntable. This was something I attended to at the time, which doesn't "make sense" -- it doesn't support any point about the narrative. In fact, it's still one of my favorite records.
I place a high value on basic honesty, and I'm very often ashamed. Shame is one way to confirm. I don't tell stories to be entertaining. I'm not entertaining. The force of shame of memories can be confirmation.
Implanting memories requires a conscious effort on someone's part. Either it's part of an experiment, or it's ideologically driven, or fear-driven, or process-driven. (Therapy, interrogation, barroom story-telling, lying, posturing.)
It's possible that our journalist is constantly telling stories and hearing stories and is constantly preoccupied with appearance, with how he's going over with his audience. This would be socially-driven confabulation.
Another general way we confirm the accuracy of our memories is by the daily effort of getting along in the world. As I've gotten older, in the last few years, I can observe my own failings and slips. (Here I'm only arguing against the radical possibility that everything's misremembered or made up.) If your memory is completely unreliable, you can't function. (Which is why
Memento is fiction. No one with radical memory loss can survive unless someone else takes care of them .)
I remember the car accidents, but I don't remember what color the cars were, because I don't pay attention to that kind of stuff. Nor do I remember when exactly they happened. I only remember the basic narrative. If I was reasonably perceptive and honest with myself at the time, and I haven't been interrogated or coached, that basic narrative is true.
