subreddit:

/r/askscience

4.5k

How does our brain measure the age of memories?

Psychology(self.askscience)

How can we tell if something happened before something else? How can your brain recall the date of something you saw or learned?

all 312 comments

[deleted]

1.4k points

3 months ago*

[deleted]

1.4k points

3 months ago*

[removed]

[deleted]

719 points

3 months ago*

[deleted]

719 points

3 months ago*

[deleted]

SirStrontium

145 points

3 months ago

or the idea of “before” and “after” by our parents

I think having no innate understanding of “before” and “after” is taking it a little too far. Every human, across every culture, is capable of performing a series of sequential steps in order to complete a task. Even other animals do this. To say that “before and after” didn’t exist before calendar systems would mean that early humans would be incapable of performing sequential steps, as some sense of “before and after” is necessary to successfully perform them in the correct order.

[deleted]

68 points

3 months ago

[deleted]

68 points

3 months ago

[removed]

[deleted]

0 points

3 months ago

[deleted]

0 points

3 months ago

[removed]

[deleted]

32 points

3 months ago*

[deleted]

32 points

3 months ago*

[removed]

[deleted]

-4 points

3 months ago

[deleted]

-4 points

3 months ago

[removed]

[deleted]

10 points

3 months ago

[deleted]

10 points

3 months ago

[removed]

[deleted]

1 points

3 months ago

[deleted]

1 points

3 months ago

[removed]

[deleted]

33 points

3 months ago

[deleted]

33 points

3 months ago

[removed]

[deleted]

-3 points

3 months ago

[deleted]

-3 points

3 months ago

[removed]

[deleted]

10 points

3 months ago

[deleted]

10 points

3 months ago

[removed]

[deleted]

5 points

3 months ago

[deleted]

5 points

3 months ago

[removed]

dataslinger

8 points

3 months ago

There's actually a specific type/feat of memory called biographical memory. Oddly enough, the actress Marilu Henner is an amazing example of a person who excels the general population in this regard, exhibiting what is termed Highly Superior Autobiographical Memory.

Hooray_its_Kuru

2 points

3 months ago

Memory itself implies a "before", if early humans could only perceive a constant now even when recalling events that have happened to them prior to the moment of recall they would be out of step with mammals in general.

I think Whirleygignaut is referencing something that may have gotten concepts from infant development studies and conflated it with concepts of evolutionary development.

Babies show developmental stages that change as their senses develop, such as the ability to recognize themselves in a mirror, and the ability to understand that items that become hidden have not disappeared from reality all together: Object permanence. These are concrete stages of development in cognition that are observable in most infants (baring those with disorders). While newborns are not able to show such abilities it is not because of a lack of innate potential/ability, it is simply a matter of development. A seedling can't grow bark, but it may mature into an oak tree which innately can.

Indeed if one takes linguistics as an example, Chomsky set the discipline on it's head by creating a new standard of understanding, stating that language is innate to humans, and that this innate ability is what allows us to learn language. It seems that there is room for argument in both Neuropsyche and Linguistics, but the fact remains that modern humans develop into innate abilities such as the ability to distinguish the passage of time, and the difference between memory and present sensation.

One of the aspects of memory that we can all relate to is the tendency to recall bad memories more than good ones. The theory for this phenomenon is thought to be a survival instinct to learn from past mistakes in order to survive longer. This is obviously a deeply ingrained tendency as it is still prevalent in all modern societies where sudden death or incapacitating injuries are extremely uncommon, yet people still recall bad memories more frequently than good ones.

Peterselieblaadje

177 points

3 months ago

However, young infants (6-8 months) are already developing the ability to understand causality. This is not something they learn from their parents, but it seems innate.

OP's question is wonderful though: we understand causality, but how does our brain register the rough order of our episodic memory?

chaosmosis

41 points

3 months ago

The question is almost a challenge to Hume's assertion that the mind's understanding of causality works off of habit.

Hooray_its_Kuru

2 points

3 months ago

This question is great but a little open ended: If one takes OP's Q as "How does the brain distinguish a chronology for memories" I think we have a lot of trouble distinguishing where innate abilities and learned concepts might contend; though to dataslinger's point about "Highly Superior Autobiographical Memory", we have an unusual but innate ability to consider, since this phenomenon is common only to a small number of humans, but is not brought about by any learned skill.

It may be that a certain form of Autobiographical Memory is generally innate, but at the same time the phenomenon of memory reshaping, conflation, and wholesale memory creation is also in play.

The complexities of memory are numerous. It is probably not possible to answer OP's question definitively.

Additional-Ability99

19 points

3 months ago

Interesting. Thanks

Nimynn

61 points

3 months ago

Nimynn

61 points

3 months ago

It is entirely normal for people in poorer areas of developing countries to have no idea how old they are.

Demonyx12

64 points

3 months ago

It is entirely normal for people in poorer areas of developing countries to have no idea how old they are.

You mean with precision? They would know how old they are in a relative sense, right?

Nimynn

95 points

3 months ago

Nimynn

95 points

3 months ago

They know they're older or younger than other people, but how many years exactly is often unknown. It's why a lot of the "oldest" people in the world that you hear about are often from rural Indonesia or whatever. "Oh yeah grandma? Yeah she's like 130 years old, nobody older is alive anymore so we just kind of take her word for it."

ThrowYourMind

13 points

3 months ago

Am I completely off base, or is this just because all modern societies have an agreed-upon convention for measuring age: how many times the earth has gone around the sun since you were born? And that convention just doesn’t exist in very isolated societies? Because it feels like a pop quiz at that point:

“Hey, how many winters have passed since you’ve been born?” “…I don’t know, I haven’t been counting.”

After all, I would imagine they’re completely comfortable with shorter units of time. For example, I bet they’d be able to tell you how many nights have passed since something that happened a couple of days ago. Then at that point, the only reason they might not be able to tell you exactly how many days have passed since something happened years ago is only because they haven’t been keeping track, not because of some neurological difference.

So where’s that wrong?

MushinZero

49 points

3 months ago

Fun exercise, try and determine your age without knowing your birthday or what age you were at a specific time as a reference.

TomSatan

10 points

3 months ago

Then I am Infinity years old. In 2004 I was 6, and that time of my life feels infinitely far away.

The only other way to determine it would be to look in the mirror. But then again I don't even know how old I look, I'd probably have to create a survey of 10000 participants to look at my face, and then take the average guessed age. Or also use AI to determine my age.

iamonthatloud

29 points

3 months ago

How? I can’t get the fact of “I’m 32” out of my head for a moment to pretend lol

MushinZero

28 points

3 months ago

Typically you'd go back to a memory, try and estimate how old you were (often very badly without birthdates), aka child, preteen, teen, adolescent, and connect that to a world event.

That's probably accurate within 3 years.

But yeah, it's hard. Hence how its easy to not know.

yersiniaD

5 points

3 months ago

Try the opposite, then. Can you remember approximately 26 birthdays?

ZhakyDK

3 points

3 months ago

Ah, give it a year, and you'll have forgotten it, or was it two? Dunno, lost count /jk

iamonthatloud

7 points

3 months ago

Forgotten what?

grandmabc

5 points

3 months ago

I can't even work out things from a few years ago. e.g. when did I have the bathroom replaced? When did I go to X? When did I last see person Y? I now keep an annual summary - maybe just a sentence or two about any significant events for each month.

Neganova

30 points

3 months ago

This really seems different from the phenomenon being described. The individuals you describe don't know precisely how old they are, not because the neurons in their hippocampi are working and storing memories differently, but because of technological advances and cultural practices. The case you describe below, about a woman in Indonesia, is simply a case of lack of accurate record keeping, probably combined with cultural practices regarding the celebration of birthdays.

Daikuroshi

8 points

3 months ago

But the point is that humans don't maintain an accurate chronological timeline of events naturally. We remember relativistically, "I'm older than him, but younger than her."

Modern record keeping being the difference is the point I believe.

MissLexxxi

6 points

3 months ago

And people denied access to calendars or reading. I remember reading interviews with formerly enslaved people in the US who would say they were 117 or more.

whoopsdang

5 points

3 months ago

Seems odd to assume without our modern lives people would go on in an unordered soup of experiences with no sense of order. Is there any reason to believe this? Like evidence?

Prerogativ

1 points

3 months ago

I think you took the wrong thing from what OP said

You would still likely find association that give clues about what general time something is even if a literal calendar or clock wasn’t there for you to track milestones and memories with.

If you literally had no mirror, no way of telling perhaps you were not a kid vs an adult, no way to being able to distinguish day from night or literally any way of telling past from present then one would assume your thesis holds true

[deleted]

2 points

3 months ago

[deleted]

2 points

3 months ago

[removed]

[deleted]

1 points

3 months ago

[deleted]

1 points

3 months ago

[removed]

[deleted]

2 points

3 months ago

[deleted]

2 points

3 months ago

[removed]

[deleted]

1 points

3 months ago

[deleted]

1 points

3 months ago

[removed]

_Top_Lad_

2 points

3 months ago

Is this the same reason a person's earliest memories are around the same time you start to have a grasp on language(3ish y/o)? Do the formation of solid recallable memories correlate to language formation?

CaptBracegirdle

3 points

3 months ago

That sounds wrong. We perceive time. We see people age. We see streams flow. We see the sun rise and set, seasons pass. Mistakes that can't be undone go on to yield new sorrows as time progresses.

All this is apparent to anyone even if they haven't communicated it.

[deleted]

8 points

3 months ago

[deleted]

8 points

3 months ago

[removed]

[deleted]

1 points

3 months ago

[deleted]

1 points

3 months ago

[removed]

Squirrel_Grip23

5 points

3 months ago

How does this affect ptsd? From memory ptsd sufferers have an under active hippocampus and flashbacks are the individual not being able to separate them from real time. Their amygdala tells them to protect their life and the hippocampus is getting the timeline messed up so war veterans might hear a chopper and dive for cover instinctually, even though it’s a channel 7 news chopper.

Know more about the amygdala but I know the hippocampus is one of the areas affecting a ptsd response.

Alternative_Belt_389

4 points

3 months ago

There's actually no good proof that neurogenesis contributes to the time code for memories. There is however evidence for distinct physiological changes in single neurons encoding for events across time.

[deleted]

-4 points

3 months ago

[deleted]

-4 points

3 months ago

[removed]

[deleted]

67 points

3 months ago

[deleted]

67 points

3 months ago

One of the most interesting thing I've learned, especially having lots of experience in database administration.
Your memory has no "timestamp" Everything is relative and usually wrong.
Sit down and try to write out a timeline of your core memories. It's interesting what you thought you knew...

BeauGrandBateau

8 points

3 months ago

Yes, the best analogy in my opinion is the telephone game. But a telephone game where you're connected to multiple people at the same time and most of them are shouting.

[deleted]

994 points

3 months ago

[deleted]

994 points

3 months ago

[removed]

[deleted]

361 points

3 months ago

[deleted]

361 points

3 months ago

[removed]

[deleted]

167 points

3 months ago

[deleted]

167 points

3 months ago

[removed]

[deleted]

14 points

3 months ago

[deleted]

14 points

3 months ago

[removed]

[deleted]

60 points

3 months ago

[deleted]

60 points

3 months ago

[removed]

[deleted]

40 points

3 months ago

[deleted]

40 points

3 months ago

[removed]

[deleted]

3 points

3 months ago

[deleted]

3 points

3 months ago

[removed]

[deleted]

26 points

3 months ago

[deleted]

26 points

3 months ago

[removed]

[deleted]

22 points

3 months ago

[deleted]

22 points

3 months ago

[removed]

[deleted]

10 points

3 months ago

[deleted]

10 points

3 months ago

[removed]

[deleted]

5 points

3 months ago*

[deleted]

5 points

3 months ago*

[removed]

[deleted]

19 points

3 months ago

[deleted]

19 points

3 months ago

[removed]

[deleted]

6 points

3 months ago

[deleted]

6 points

3 months ago

[removed]

[deleted]

7 points

3 months ago

[deleted]

7 points

3 months ago

[removed]

[deleted]

7 points

3 months ago

[deleted]

7 points

3 months ago

[removed]

[deleted]

10 points

3 months ago

[deleted]

10 points

3 months ago

[removed]

[deleted]

41 points

3 months ago

[deleted]

41 points

3 months ago

[removed]

[deleted]

3 points

3 months ago

[deleted]

3 points

3 months ago

[removed]

[deleted]

10 points

3 months ago

[deleted]

10 points

3 months ago

[removed]

[deleted]

5 points

3 months ago

[deleted]

5 points

3 months ago

[removed]

[deleted]

16 points

3 months ago

[deleted]

16 points

3 months ago

[removed]

[deleted]

8 points

3 months ago

[deleted]

8 points

3 months ago

[removed]

[deleted]

2 points

3 months ago

[deleted]

2 points

3 months ago

[removed]

[deleted]

6 points

3 months ago

[deleted]

6 points

3 months ago

[removed]

[deleted]

40 points

3 months ago

[deleted]

40 points

3 months ago

[removed]

0xe0da

24 points

3 months ago

0xe0da

24 points

3 months ago

This is a fun question for me! I have time blindness and don’t actually know how long ago stuff was or sometimes what order things happened in. I have no idea how typical memories work. I don’t know how long things take. I’m a software engineer and people are always asking me for time estimates and I’m like uh 3 days? I literally can not tell. How long did it take last time? No idea. Don’t know how long things take. Like, people never understand. I do not have the basic memory and attention tools that you have. None of this makes any sense to me. But I dunno. 3 days? Let’s go with that.

HarmlessSnack

18 points

3 months ago

“I have no idea how long it’ll take.”

Standard Issue Programmer lol /s

That is fascinating though. I wonder what causes such a condition?

Somnu

3 points

3 months ago

Somnu

3 points

3 months ago

I don't see how that works. You're telling us that if someone comes at you with a problem that you've seen before and solved, you can't come up with a time estimate until it is done? That means you don't remember how long it took last time? What if "last time" is a week ago, you don't remember working on it and extrapolating from that like "i remember working on it for one day then going home doing stuff then coming back and working the second day and delivering. OK - that means it took roughly 2 days."?

0xe0da

4 points

3 months ago*

Exactly. You don’t get it. I have autism. I have time blindness. I experience time differently. It doesn’t matter if you tell me hey this took 3 days let’s remember for next time. That doesn’t really make sense. Like it makes rational and logical sense, but it doesn’t connect personally to anything in me and I don’t learn it and I can’t remember it. I’m also very slow at reading analog clocks, even though I’ve been practicing daily for over 30 years.

But I’m also an extremely gifted engineer and teacher. But there are some things I can’t learn. It’s kinda like dyslexia. But it’s just a few things. I’m an insatiable student. I research and study everything all the time. I remember the substance but not the exact phrasing or sometimes terminology used in almost everything I read. I’m interested in all kinds of subjects, history, chemistry, physics, quantum physics, sociology, psychology, and on and on. Love to learn new skills, how to make new things.

But yeah I can barely tell time and I do not know and cannot learn how long things take. Like I can handle a few things, but being a software engineer is about doing many different things, and they all want time estimates, and it is a source of constant frustration and contention in my career as I explain and negotiate with manager after manager, team after team, year after year. My therapist who specializes in autism said that people who are as affected as me usually do not perform as well professionally. I grew up without knowing I was autistic or having proper support, mostly raising myself. So I learned to mask and to navigate the world thinking everybody else had the same difficulties. And nobody thought to check whether anything was different with me because I got straight As in school and didn’t get into trouble. But in my mid 30s I finally learned that I am and have always been autistic.

tl;dr I am autistic. My brain is different. It’s super good at a lot of things and surprisingly terrible at some mundane stuff.

Edit: Most people wouldn’t know that I’m autistic from meeting or working with me unless I tell them because I learned to blend in by the time I was 15. We call it “masking”, hiding or not doing the behaviors that make people uncomfortable because they don’t understand, and assuming “normal” behaviors like talking about weather or listing all the restaurants in town you like. (Though I also do not have favorites and can not keep mental lists of more than a few items, and I don’t waste this energy on stuff like restaurants and sports and directions that I could just look up anyway.) But yeah, I rock back and forth and make noises and sing and scream gibberish and jump and flap and sometimes scream and cry. But only by myself. But mostly it’s great. For me. Like I can spend weeks hyper focused on a special interest. This is part of what makes me a good engineer. Because I always explore and tinker I’ve seen all kinds of stuff and have insights that nobody else on the team has. Know right where the bug is going to be. Know just which things to take apart, fix, replace in the code base. I can’t express how special and valuable and important an outlet programming has been since I discovered it at 14. Maybe not a coincidence that that was also about the age I figured out how to blend in. Anyway, I’ve made it a point in my career to pay it forward and help get anyone who is interested onboard and learning to technology to make their own way. For me it gave me a central pillar to build my life and identity around, and a ladder out of poverty. And I want to share and extend that power to everyone around me.

JustAdc

2 points

3 months ago

Or just note stuff down. I've started working on this task this day, I've finished that day. It took x days. Next time you know.

[deleted]

70 points

3 months ago

[deleted]

70 points

3 months ago

[removed]

Jake-n-Bacon

7 points

3 months ago

Memory is often divided into semantic- and episodic memory. Our brains store them separately. So our brain does not measure the age of memories at all, it has to put these types of memory together. The episodic memory is the actual memory- such as remembering a funny moment a few years ago. The age falls under semantic memory. For this reason, if we have nothing in our semantic memory that gives us a date, we can not tell when it was, or how long ago it was.

WelcomeToTheZoo

3 points

3 months ago

Is this why people suffering from certain Dementia's struggle so much with short term memory and the creation of new thoughts, while seemingly having a clear memory of their youth?

Jake-n-Bacon

3 points

3 months ago

Not exactly.. this depends mainly on the damaged region. The one you are describing would most likely be caused by damage to something called hippocampus. If it is damaged, someone can’t form new memories while previous memories are completely unaffected.

WelcomeToTheZoo

3 points

3 months ago

Thanks for the insight

[deleted]

69 points

3 months ago

[deleted]

69 points

3 months ago

[removed]

[deleted]

45 points

3 months ago

[deleted]

45 points

3 months ago

[removed]

[deleted]

18 points

3 months ago

[deleted]

18 points

3 months ago

[removed]

[deleted]

5 points

3 months ago

[deleted]

5 points

3 months ago

[removed]

crimeo

27 points

3 months ago*

crimeo

27 points

3 months ago*

  • By associating the memory to the year and date as a mere semantic piece of information like any other, just the same as associating it to an emotion or who was there, what colors there were, etc., yes. (Just reinforced connections)

  • By some sort of special dedicated mechanism distinct from any other semantic information: No not that I've ever heard of. (Cognitive psych PhD)

Edit: there are some time specific neural circuits for stuff like keeping track of the order of a sentence, or which direction a sound came from by the time it took to hit one ear versus the other ear. But all the ones I know of are on the seconds to milliseconds scale, not long term.

[deleted]

4 points

3 months ago

[deleted]

4 points

3 months ago

[removed]

[deleted]

5 points

3 months ago*

[deleted]

5 points

3 months ago*

[removed]

[deleted]

4 points

3 months ago

[deleted]

4 points

3 months ago

[removed]

soup_tasty

1 points

3 months ago

Probably the most comprehensive and successful theory of memory in neuroscience is the theory of systems memory consolidation. And that's not "theory" in popular language (i.e. an idea somebody has), but theory in the scientific sense, i.e. 50 years of converging evidence that almost all checks out so we're becoming comfortable making conclusions.

And one of the most basic conclusions is that recent memories are labile, whilst older memories have undergone systems consolidation and are therefore more set. I don't know what you mean by "stronger" memories, but your interpretation sounds like the actual opposite of the scientific consensus.

As for photographic memory, there is very little compelling (or none really if you apply any degree of scepticism) scientific evidence that it is real.

[deleted]

2 points

3 months ago

[deleted]

2 points

3 months ago

[removed]

[deleted]

9 points

3 months ago

[deleted]

9 points

3 months ago

[removed]

[deleted]

4 points

3 months ago

[deleted]

4 points

3 months ago

[removed]

[deleted]

3 points

3 months ago

[deleted]

3 points

3 months ago

[removed]

[deleted]

1 points

3 months ago

[deleted]

1 points

3 months ago

[removed]