Being an "aging brain" myself I can totally relate to this. I've been a relatively obsessive photographer (i.e. visual diary) since digital cameras were practical, i.e. over 25 years now. 238K photos in the collection so far, and I can actually find things in it.

And I've more than once found that an anecdote I've been telling has been incorrect, precisely in a "melded memories" kind of way. It happened at this sort of gathering which were usually held for that reason so X was involved... and then finally look at the old pictures and there's no sign of X. It is literally the brain invoking "lossy compression" to make it all fit, just like certain web services that let you upload pictures without limit might reduce old ones, that hardly anyone ever looks at any more, to lower quality to limit storage bloat.

Of course any married man can confirm that this only applies to men. Women's memories are flawless. If they claim that they remember a conversation exactly, word for word, 20 years later, who's to prove them wrong?

I wonder how much of this is directly related to age (biological aging), and how much is just someone's brain becoming "full" due to more memories getting added every year?

It seems that memories must be stored as embeddings with single multi-neuron assemblies (cortical columns?) storing multiple embeddings as a kind of contents-addressable memory that is able to keep memories distinct due to the very high dimensional space (# neurons per assembly) being used. However, you'd expect that at some point if you store too many memories in a single assembly the recall accuracy is going to go down.

You'd expect that with big brains being so costly, evolution has only equipped us with brains big enough to store a lifetime of memories, so it would be odd if memory didn't suffer as we get old.

To make a computer analogy, it's a bit like a hash table getting too full. Say you had a hash table without any overflow mechanism... up to a point recall may still be pretty good, but as the table gets closer to full there will be more hash collisions and likelyhood of "false recall". Obviously the brain is not a computer, but the analogy may hold up reasonably well if you consider the hash table keys and values as embeddings and the store operation being an embedding merge rather than overwrite.

Is it aging or the extra amount of information on the brain? If a young man is in a coma and wakes up as an old man will he experience the blend memories or will he remember things just as they were when he remembered them as a young man?

There's also the issue of the more we remember something the more we change it. Which could contribute to the blended memories.

The paper certainly has its limitations. Only 61 participants, with almost nobody between 30 and 50, so we shouldn’t read the age trend as a decline across lifespan. What’s more interesting than the title suggests (and I find the title forcing the conclusion a bit) is that the attention measures were not linked to age or the brain patterns at all.

Then again, i'm 45 and I've been losing my keys and my IDs since I was 20

The concept of memories blending together resonates after watching a recent Kurzgezadt video entitled "How Are Memories Stored Inside Your Brain?". It makes the point that the very act of recalling a memory changes it:

https://www.youtube.com/watch?v=PqtggjVAi8M

> But memories are not static like photos. Like dioramas made from wax, each time they’re under the spotlight of your attention they can melt and change a tiny bit.

Gonna chuck a thought for you all. In social situations there is someone who talks alot and I think they are able to do so because they have lots of stories they can recall in good detail (maybe not perfect) but 20 year old event they are describing better than I can describe last week. Now I assume they don't have that rare calendar level memory but they do have a huge storage of stories and events. I am pretty jealous tbh!

Also that skill is probably excellent for interviews which is the ultimate memory test. I.e. Tell me a time when you turned water to wine, plus 5 deeper questions, any hesitation will be chalked ip as suspicious AI use.

For me I either do or I remember which makes performance management and interviews hard for me (as someone vouching for someone as evidence is rare now).

My theory behind this is that when you encounter something new/novel it is distinct enough to remember -- where you were when you learned of 9/11; the days around the start of covid/lockdowns; being in a car accident; getting married; etc..

However, when you experience the same thing repetitively -- having breakfast; getting ready for school/work/etc. -- it doesn't make sense for your brain to remember each of these events as distinct events but to mush them together into a single or combined memory. This may be due to how the brain indexes/references memories and that memories with the same references get combined together.

This is also partly why time appears to go faster when you get older -- the same day-to-day events blend together but the key milestones (holidays, etc.) stick out.

Compacting ———-~~~~~~~ 40%

This comes as absolutely no surprise to me -- my mother was recently transferred into memory care, and the changes to her memories are definitely showing some interesting changes. The foremost was that her new "apartment" is shared with one other person, gives off a bit of a dorm room vibe. First day, she was talking about how excited she was to be going back to school and seeing her boyfriends again(?!). I said, "Oh, like Doug? [my dad]". Her response? "Ew. No."

But, she's come around on that, and recently been upset about the affair he's been having (they divorced in 1980), and is irate over him having another kid with his new wife (1983), but isn't surprised that I haven't spoken to him in 12 years. She's never surprised at how I've aged, but doesn't remember her grandkids even exist and insists on meeting them soon (but remembers them when she sees them). Two weeks ago, she called to yell at me for things I did in high school (1990). At this point, I seem to be the anchor for everything recent, but when I'm not around physically, it's scattered everywhere else.

My dreams imprint stronger than reality. This has the unfortunate effect of sometimes recalling memories as real, when in fact it was all a dream.

I have some memories that I know for a fact are wrong in a pretty particular way. They’ve either become attached to the wrong place or the wrong time.

Like I remember a good friend picking me up from my childhood home, yet I didn’t even know that person until I’d long moved out (many years) from that place.

Did they really need a ai image for this article? https://stock.adobe.com/images/elderly-man-with-illuminated-...

For those getting locked out due to using an ad blocker: https://archive.ph/rPdSW

And the actual study: https://academic.oup.com/cercor/article/36/7/bhag114/8758582

How much of this, I wonder, is a function of the fact that our circadian rhythms get less robust with aging. The circadian clock hugely influences learning and memory processes, gating when you can learn and how much, and shaping the storage and recall also.

We know that with age the amplitude of these rhythms can decrease, as can the synchrony between cells.

This kind of mid-management seems to have at least some circadian component, and it would have been great if they looked to see if the effects were equally bad at all times of day, and knew the chronotype of the participants to use as a reference. I’d love to see if every test participant was tested at their cognitive peak, too.

Anecdatum: I confidently told a woman that her son, who was looking for a research opportunity in Berne, Switzerland, was heading for the birthplace of the World Wide Web, which is actually a couple of hours west and south at CERN.

I feel that anyone who has cared for someone with progressive brain degeneration has seen this a million times.

My grandmother has dementia, and if you know her you can see exactly which events/memories she's erroneously combining.

Worth keeping in mind also is that memories are not a reliable facsimile of objective reality.

Instead, they are selective representations of parts of a subjective experience. It also means that memories aren’t static, but shift over time and can even be imagined.

Clearly the hash table is filling up so you get more hash collisions.

I feel like we didn't need a study to tell us this but its always nice when science confirms something we know to be true.

I can't wait to tell my dad about this study. We recently got into a heated debate when he insisted that I was a toddler on a family vacation we were reminiscing about, when in fact I was a teenager on that particular vacation, and he was mashing it together with memories of a different vacation. He is 75 but is in pretty good cognitive health, no signs of dementia besides this unreliable long term memory.

This I belive, I used to have intimate knowledge of my niche internet lore and keep learning I am blending years around.

As a person who used to be a super genius then turned 40 and is now only a regular genius aging has been very hard to get used to.

It's interesting to compare and contrast LLMs and biological brains. Both use a form of "compaction".

Huffman Coding! :-)

Things seen at a distance blend together, as opposed to just disappearing.

So that's an interesting parallel. Says something about memory.

the basins merge

FYI this is LLM slop. Consider the information to be entirely unfounded.

/compact

[flagged]

This a covert op to buttress LLM support by planting this article and having people say it's just like compacting. The hype is getting more elaborate.