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Comment by gluelogic | Hacker News Reader

So you're saying it's a hard number and, one-for-one, if something new goes in, something old goes out?

Pretty much. Since around my late 20s everything new going in has been at the expense of something old. The only interesting thing is the loss is not a first in, first out system nor is it based on importance. I have retained pointless memories from the past and lost things that were quite important. All I can say is that my capacity is finite and I have reached the limit.

I'll concede that this might be true - but you most certainly can't validate it based on these descriptions. In fact, by definition, you are unable to forget "something" for every other "something" you learn. In fact - if you know you forgot something - is that not a new piece of information? Now that I'm writing it out I think it's definitely nonsense actually - sorry. As a parallel consider music (a "single" domain for simplicity) - you are implying you can hear a new song and forget an old one, AND KNOW that you forgot an old one(?). You're trolling us for sure.

No I am not trolling. The reason I know (more precise I think I know) that every new piece of information I learn is at the expense of something old, is that the old is not always lost without the metadata about the old being retained. I am often left with the memory of having once known something, but now lacking the actual knowledge. To give you an example I often come across plant species where I know I once knew the name (I can even often remember where I first learned its name), but I can now no longer tell you what it is. Basically I have memories of what my brain used to be like without it being like this anymore.

I experience a very similar thing. You aren't alone in being able to look at meta-states of your mind and realize it's different, or things are slipping.

For me, I noticed I no longer had instant recall of various remote control buttons. Was a small thing, but until that time, I stored maps of buttons and modes for everything. Now, I sometimes do, but I find I have the general rules, and need to parse devices and apply them now, not just thought as action as it was before.

So you forget things. Everyone does. Now demonstrate that forgetting is caused by learning. It seems you just assumed that part.

One way of demonstrating this is if the rate of forgetting old information increases when you are doing some intense learning (either studying in school, or taking additional vacations, etc).

Has that been your perception? How do you measure that?

This is definately hard to prove particular since we are talking about my own perception of my brain. Due to the nature of my career I have never had to stop learning new concepts and skill and the pace of this learning has been pretty constant over the last 25 years.

What I can say is that up until my late 20s this learning did not seem to come at the expense of past learning or memories. Since then I have noticed that while I can still learn new things at around the same pace as in the past, that new learning seems to kick out the old.

Since my ability to learn has not changed (I have had to do courses and other external tests that confirm this personal observation), then the most parsimonious explanation is that new learning is coming at the expense of old learning which is just another way of saying my brain is full :)

Of course it is possible that my memory storage capacity is just getting smaller with age, but if this was the case I would expect it to impact on my ability to learn new things now. My perception is my brain can hold around 30 years worth of learning and as you get old that capacity gets stretched to the point that gaps start to appear. While better than the alternative, getting old is not good :(

Kind of like how I can't remember a thing about a rafting trip I was supposedly on when I was 19, but I clearly remember running into someone I was on that trip with, and discussing/reminiscing about it, when I was 22. So at 22 I clearly had the memory (enough to talk in detail about it), and I now (more than 20 years later) have a recollection of that conversation, but other than that the memory of that trip at 19 is totally purged. (except some vague recollection about glowing moss in the woods).

I think it's possible to know that you forgot something. You can remember the title of a song, but the lyrics/details are deleted and replaced with a much shorter "memory was deleted to free space" message :-)

This is true - the metadata about a memory and the actual memory are often stored seperately. In regard songs memory loss seems to occur with the song title before the cord progression is lost. This results in the classic old person lament that all new music sounds the same.

You can take a hash, delete the file, and record the deletion. You'll use less space, know something is missing, and even be able to identify the deleted file if you encounter it again.

Or maybe you can jam an SSD in your ear and use it as swap space?

I thought this was why people carry around phones - why remember anything when you can just ask siri?

So then the brain must have some kind of weighting algorithm to decide what memory of equal value to jettison. Surely learning a few new URLs poses no risk to remembering which kind of car you drive?

And on the subject of memories, are all memories information? If you learn something new in mathematics, do you risk losing the memory of the cake at your fourth birthday party, or only something technical you learned about archery?

Also, if what you are saying is true, you are vulnerable to a DoS attack on your brain. I could flood you with new information right now and, if you read it, you might not remember your mother's name by the end of it.

Your mention of the idea of DoSing someone's brain reminds me of Ewen Cameron's experiments attempting to "depattern" people. (see http://en.wikipedia.org/wiki/Unethical_human_experimentation... )

Rather horrifying.

Cameron's "experiments" (torture) seemed to revolve more around sensory depravation and electric shock therapy (one of the major side effects of electro-shock is serious memory loss).

This does bring up an idea I had from years ago where instead of making prisons as boring as possible we make them amazingly interesting places where the prisoners have to use their brains constantly all day. The idea being that all this information will slowly push out the ideas and thoughts of the old person to be replaced with a new ideas and memories that make the person less likely to commit crime once released. The person should come out of prison a better person than they went in.

I've found that my weighting is a function of recall. The more often I recall a memory, the more likely I am to continue to remember it, conversely unrecalled memories tend to fade more and in a sense become compressed or move to cold storage which requires more concentration to recall.

I've always assumed this was an evolutionary result of weighting memories based on their usefulness, wherein the most useful memories are correlated with their recall frequency. I.e. they are the most useful for surviving my day to day life since I seem to need them a great number of times.

I am pretty sure that passing-out and altered states of consciousness are the brain's anti-DoS measures. You would have to counteract all those measures to successfully DoS a brain, and that would probably take a lot of drugs.

I doubt that. It is more likely that you are impatient. Recall of older experiences can be frustratingly slow.

To recover old info, first concentrate on it and recall as much as possible (what you call "metadata"), and then simply cease focusing on it. Your mind will "re-hydrate" the archived experience in the background. Sometimes this may take a day or two, but usually it requires less than 10 minutes.

Reconsider the memory periodically: each time you should feel an indicator of whether progress is being made (even though the memory isn't yet fully recovered).

One of the problems with doing this is the "recovered" memories are not exactly reliable.

One of the good things about my memory is if I remember something it accurate. I used to win lots of bets (for drinks mostly) by exploiting this - people would tell me X happened and I would say no it was Y and would they like to bet on it. I was always amazed at how many people would accept these bets even after losing to me many times - it seemed they forgot that I had an accurate memory :)

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