This is a question that’s been bothering me for a while. I’m a writer and like to ponder certain impossibilities and can usually sort things out with a few minutes of inner socratic dialogue, but I’ve been stumped on this one.
Allowing for the possibility that someone could live either forever, or an impossibly long time (over a thousand years), could his brain handle that?
Every waking moment we are taking in extraordinary amounts of data via all of our senses and cataloging it into our brains via our subconscious. And I presume that if a human brain is anything like your average teacup, it can only hold so much stuff.
If you lived for thousands of years, you’d be accumulating quite a lot of memories up in your noggin.
Is there really such a limit? And if so, what would happen as you approached it? Would you begin to completely forget earlier memories as new ones replace them? Would you simply go insane from information overload? Would you just suddenly die at some point by having a few too many axons and synapses get crossed?
With the “forgetting” situation, keep in mind that your brain rarely (if ever) actually forgets something completely. You can always be reminded of something, and the memories come back. The memories aren’t so much deleted as they are simply misplaced. A 75 year old still has memories from being 5 or 6 years old in his brain, even if he can’t recall them.
For the sake of this hypothetical, lets assume that whatever magic is allowing our subject to live indefinitely doesn’t affect him in any other measurable way. That is, the live-forever spell wouldn’t include a clause for not-going-bonkers.
Further, lets ignore the effects of aging/senility/etc.
The things is the brain isn’t a computer, and it doesn’t work like one. Computers store information as a series of bits, literally as the presence or absence of information. Thus when a computer stores a memory of a face for example it literally memorises what parts of the face contained nose, and what parts didn’t, so a person with a large nose will simply have more information in the ‘nose’ part of the picture and less in the ‘cheek’ part pf the picture. That sort of processing works well for retaining very fine detail but it is hard to compress. It is also wasteful of space because in order to memorise a person the computer needs to memorise the face as a whole, the body as a whole, specific identifying markings at an appropriate level of detail. Then it needs to store different pictures of the person when happy, when sad and so on.
In contrast the human brain, as far as it is understood, stores information as reference information. So when a person starts life they memorise a specific face, presumably their mother’s. That initial memorisation is probably just as memory intensive as the way computer does it, relatively. But the efficiency of the brain is that every other face is stored as a reference to that. So Dad is stored as Mom with a narrower face and a beard, that’s all the information needed to distinguish those faces. Then Uncle Dave is Dad without a beard and with glasses. And the babysitter is Uncle Dave without the wrinkles, and with a longer nose. And that goes on throughout life.
The beauty of that system is that, in theory, the memory capacity of the brain is nearly infinite. Every new piece of information is referenced to previously memorized information, meaning that as the amount of information increases the amount needed for the next piece is reduced in proportion. The first face might take 10, 0000 ‘bits’, but the second face will only take 500 bits because it is just a header file referring to the first face and with a simple instruction to narrow the first face and add a beard. The next face might only take 100 bits because it’s just the first face + the second + instructions to subtract 20 years, and so forth. By the time a person knows 100 faces they can probably store the whole of humanity with header files saying “Person7s chin, person 8’s ears, person 179’s smile” and so forth. No new information is being stored per se, it is just a matter of cross-referencing existing information.
Now all those header and reference files will take up some space, so the brain will become full eventually, but it so over engineered that nobody has ever lived long enough to experience anything approaching it. People of 120 can still remember what their parents looked like, can draw pictures of their school and so on. Memories fade because of disuse, not because the brain runs out of memory capacity. As such it’s impossible to know what might happen if the brain ever reached capacity.
Hey Blake, it seems to me that you know much about psychology/neuroscience. Is your job or schooling related to that, or is your knowledge more of a hobby?
This is also how video compression (esp. DVD video) works. However, I should point out that while this is our current understanding of how our human brains work, the Mind is an ever-evolving mystery for which many hidden mechanisms still remain unexplained, and neuroscience remains at a loss to explain them.
I think the only issue with eternal life would be keeping your mind occupied. If you’re able to witness & participate in an active, chaotic world (such as the rise of human civilization) that’s a lot more interesting than, say, being trapped at the bottom of the ocean for 10[sup]15[/sup] years. Stephen King’s “The Jaunt” (from Skeleton Crew) dealt with this very topic of the mind being stuck in stasis for eternity.
Immortals would obviously need mental reboots every so often. Upgrade the wetware, defrag the memory, all that good stuff. Maybe even run alternate consciousness environments: for the next 400 years you will be Sunni Muslim or clairvoyant or really interested in accounting. Hell, if you can make someone immortal, the rest would be cake.
I don’t think a reboot would be necessary. I think the brain cuts corners in its data storage routinely. Over the course of centuries, or millennia, your memories would likely simplify, or settle into thematic templates, the way they do more subtly over shorter periods. Even people with “photographic” memories would display this sort of imprecision over a long enough period.
More recent memories would, of course, tend to be more sharp and ideosyncratic. More distant ones would be more vague, though the brain could tack more recent details on to them if they seemed appropriate.
Without making too many assumptions, I think we can agree on a few basic principles.
The storage capacity of the brain is finite.
Each new memory requires some amount of additional storage.
This leads logically to the conclusion that your brain could not store all your memories if you were to live forever. Various compression techniques can greatly extend the storage capacity of the brain, but ultimately, even storing diffs and relative comparison data won’t give you “nearly infinite” storage. At some point, you’ll be forced to discard some data.
I doubt that this will be a big deal, from either the physical brain’s point of view, or from your conscious point of view. The brain already loses detail on memories as the neural pathways go unused. I believe that some memories are literally overwritten as the neural connections change over time (although I’m not sure). And, at a conscious level, the brain is already used to processing memories at a high level, filling in pieces on the fly when they’re needed. Consider how unreliable eye witnesses are. Their memories aren’t nearly as complete as it seems, and they fill in details that sort of make sense.
So, if you lived forever, you’d probably still remember stuff from different times in your life, but you wouldn’t remember it any more accurately than you do now, and some old memories would fade as you made new memories.
I don’t think you need to postulate an immortal to see what the brain does with “excess” information. What did you do on the tenth day of second grade? How did your 437th day at your current job go? Unless those were special days, you don’t remember. Maybe someone can prompt you with a few details and get you to recall some extra details, but many of those extra details are not remembered so much as recreated.
My wife is a police volunteer who goes through a training course on interviewing and observing crime scenes. One of the tests on observation is to view a series of slides showing a person walking by a bin full of oranges and walking past as oranges fall. You’re then asked to remember things - eye color, location of bystanders, etc. One of the questions asks “Did you see the person knock the oranges down?” The correct answer is no - no slide shows the oranges being knocked down, only the result afterward. However, the majority of people answer “Yes” and their brain even conjures up an image of the oranges being bumped into. They honestly believe they remember that happening when no such image was shown to them - they not only accessed “data” in their brain, but they changed that data.
So memory is never a faithful record of information. When we remember something at all, the brain has recorded only a basic skeleton of the event - the vivid details we recall are interpretations or fabrications added at the time of recall. To use a computer analogy, it’s like storing 3-D wire frames and textures as separate files and combining them into a full image only on demand. An immortal would use the same process for a memory a million years old as you use for a memory that is one hour old. And with a million years to remember and recode the memory, the original event may be nothing like the current version of the memory.
I heard on a recent Radiolab podcast that memories are re-written (and embellished) every single time you recall them, but that a memory you haven’t accessed since its creation would have the most fidelity to reality.
If you don’t “access” (God I hate that word) a memory since its creation it will disappear completely within just 48 hours. That’s why it’s called short term memory. And contrary to popular fiction, hypnosis can’t allow us to retrieve short-term memories after more than 48 hours. Those memories are gone for good.
Memories that have been stored long term will also fade with disuse. If “a memory you haven’t accessed since its creation” has “the most fidelity to reality” then try to remember which seat you occupied in your fist grade class and who sat beside you, behind you and in front of you. You certainly could have answered this question when you were in first grade. Chances are you won’t have used this memory since the end of first grade. So according to your theory it should have perfect fidelity to reality. In truth of course the memory simply doesn’t exist. It’s gone and nothing will bring it back.
You can try the same experiment with countless other memories that were stored long term and perfectly, and that haven’t been used since. What colour was your bike/family car when you were 10? What were the middle names of all your past boyfriends/girlfriends? What are all the answers to the high school chemistry quiz? What was your Tuesday timetable, senior year of college? And so on and so forth. All those are memories that are unlikely to have been used since the last opportunity to store, and obviously you had stored them all in long term memory at the time and could have answered them without any trouble at all. But far from being more faithful to reality than memories from the same period that you have recalled continuously, they have in fact vanished. The memories have faded due to disuse.
I can only assume that what the podcast was trying to say was that, of those memories that we can still recall, those that are recalled least frequently are less likely to contain erroneous implants. I’m not sure how one would test that, but it seems plausible. However that’s vastly different from a claim that not recalling a piece of information at all from the time of formation make sit more faithful to reality. That claim is patently not true, otherwise I would remember the name and clothing of of that girl I spent hours chatting to in that club on a Saturday night in 1997, and I can’t. Nobody remembers that sort of thing.
Maybe I have super powers, but in situations like you described (first grade seating arrangement, family car color) I can almost always recall either by thinking it out (trying to recall a memory of around that time that I do remember, and playing the film forward or backwards) or someone could remind me (“remember when we did that snowman art project with cotton balls? you were sitting right next to the window.” “oh yeah, and sally was right behind be and she used to always want to borrow my scissors.”)
It could be possible that I have better recall than others, but because of this I always assumed that no memory is ever lost except for very early memories (like age 0 to 2 when the brain hasnt fully formed yet) or events taking place where memories are chemically disallowed, like just after waking up or after one or twelve adult beverages.
It could also be possible that I don’t actually remember first grade, only a few fragments of it and my brain is filling in the rest with fiction, but I dont like to give my subconscious that much credit.
I might just go with the assumption that I have better-than-average recall. I have noticed that while some people seem to remember the “gist” of events or conversations, I can remember them explicitly. Drives me crazy when people misquote conversations I was party to. That’s not what she said, dammit!
