A little from column A and a little from column B.
I have young kids and it's fascinating watching them talk about half-remembered stuff from the past. They'll start off not really remembering much and taking guesses. Then the other takes that guess as gospel and repeats it back. Now the first has more confident. Soon they are both fully convinced of a whole pile of fabrications.
It made me realize how much of our memory is socially constructed.
Excellent question, and the answer is that human memory is generally highly fallible, malleable, and unreliable.
We all have the naive impression that memory is somehow like a video recording and we can just access it to find out what happened. Indeed, we all have some very vivid and probably quite accurate memories about some exceptional events, or can recall exactly what page and what part of the page we read some specific item. There area also examples of amazing memory stunts and records, and even memory contests and championships.
But we cannot assume that just because we have some very good memories, memory is generally good, indeed, it is mostly pretty bad, especially compared to any kind of recording system.
This is supported by several areas of research demonstrating how easy it is to plant fake memories, reshape memories, and get people to be completely convinced that they are describing are exact and real.
One area of research is eyewitness testimony, which has pretty much been the standard in courts since courts existed, yet when eyewitness accounts are compared, they almost always come up with a variety of contradictions.
There's also been research into the phenomena of "found" or "recovered" memories often used to convict accused child abusers. Again, it turns out that suggestion and guidance on the part of the investigator can create things our or whole cloth, so it must be very carefully guarded against.
There's also several other research areas in which this is relevant, but the outcome is pretty consistent -- human memory is generally pretty bad (sorry I haven't got the time to track down the references).
I've found that it's best to just treat memory as merely a good hint about what might have happened (or where I might have left that tool or the keys), and then look for actual evidence of what really happened.
For example I, as well as many others on the Internet, remember the James Bond Semi-Villain Jaws's romantic interest as being a blond, pig tailed, bespectacled girl with a large smile and a mouth full of braces. We're sure she had braces, that was the whole joke! Turns out, no record of her having braces whatsoever.
Weird that a memory could permeate society like that.
It seems that our memory isn't like photos or videos - isn't recorded directly - but rather it's procedurally generated - when you access a particular memory, some the brain simulates a lot of stuff based not just on the "seed" of that particular memory, but also everything else you've experienced since. This way, future experiences can significantly change what you recall, which leads to fun experiments (and not so fun issues with eye witness reports).
A completely made-up example: imagine that you saw a colored circle. Instead of storing a snapshot of what you saw, your brain really records two things - that you saw a "circle", and that it was of your "favourite color". Many years later, you recall that memory, and "see" a blue circle. But in reality, the circle was yellow - over those years, your favourite color has changed, and since the memory stores reference to it, your recollection also changed.
Even when talking brains and memories, we still can't get away from pointers and references, huh?
I've never heard this explanation for such a phenomenon. Quite interesting.
When I remember something, or when I purposefully recall a memory, it is very easy for me to change the details on purpose even as I am thinking the thing. It is also possible to create wholly false but entirely plausible recollections (for example, "remembering" having sex with a past girlfriend in a time or at a place which we never had sex, but because we spent so much time together, I have good baseline data to produce all the most pertinent details, and my mind doesn't care about glossing over the things which are fabricated.)
It's scary to think about. I am capable of consciously replaying totally false memories, so how often are the things which I remember a product of an unconscious version of the same process? How fallible is my memory really?
> Even when talking brains and memories, we still can't get away from pointers and references, huh?
That's because they're good models of a fundamental concept of indirection :). People sometimes think it's hubris that programmers tend to talk a lot about fields they "know nothing about", but part of it really comes from the fact that programming is dealing with one of the most powerful abstract concept ever devised - that of computation.
> It's scary to think about. I am capable of consciously replaying totally false memories, so how often are the things which I remember a product of an unconscious version of the same process? How fallible is my memory really?
Yeah, it is scary, though one gets used to it. Experience shows that most of the time at least your recent memories are pretty robust. There's a lot of context ensuring the consistency and accuracy of the "procedural recollection" of a memory, but it's procedural generation nonetheless.
EDIT: want another fun programming analogy? Think about how fast you can answer questions you've already heard and thought about vs. ones that are new to you. You may come to the conclusion that the brain is mostly a massive cache, and most thoughts being cache lookups. You know the concept of "speaking before you think"? For me that sometimes happens literally, and it really smells like a partial pattern-match to a question doing a cache lookup in the brain.
And now add to this that it's been estimated that the brain itself is clocked around 200Hz (Hertz, without SI prefix) of sequential computation speed...
O remember seeing a documentary about memory where they would show kids fake photoshopped images of trips they'd never done, and then the kids would "create" those memories like that had happened and also adding more details to the fake story
