The actual brain mechanism that keeps you from changing
And how we change that.
This is the second instalment in a series on memory reconsolidation. You can read the first entry here.
Memory reconsolidation is kind of like a legacy software system. When you try to use the system for your current goals, it can feel totally ass-backwards and counter-intuitive. As in, What idiot thought this workflow was a good idea?
But legacy systems get a lot less confusing if you think about them in terms of the problems they originally solved. Features that seemed worthless make more sense. You start to grasp the underlying logic. And using the system for your purposes becomes a lot easier.
To take this approach with memory reconsolidation, we need to go back quite a ways. Further even than COBOL. Let's say about 10,000 years.
So imagine you're an ice-age human, living in a cave with some other humans, and your life is all about survival. Your days are filled with things that might be about to kill you: giant bears, rival tribes, poisonous plants, you name it.
Luckily your brain has a super-efficient way to collect and use survival-related information. Here’s an example of how it works:
One day you go into the forest and get attacked by a tribe you've never seen before. We'll call them Forest Tribe. Somehow you manage to get away and flee back to your group.
Your brain will store two different kinds of memories from this experience:
1) Episodic or explicit memories. These are what we usually mean when we talk about memories. They contain what happened, where, how, etc. When you recount the story of your heroic escape from Forest Tribe around the fire that night, you'll be using your episodic memory.
2) Implicit memories. This is the kind I mentioned in the previous post in this series. Implicit memories contain the key takeaways from significant experiences. In this case, the takeaway might be something like Forest Tribe wants to kill you. Basically, your implicit memory is a storehouse of key predictions for what is likely to happen or rules about how the world works. These predictions get reactivated whenever your brain thinks they are relevant to the present context.
So let's say a couple of years later, you're in a different area that looks like where you got attacked by Forest Tribe. The similarity triggers your implicit memory to power up the Forest-Tribe-wants-to-kill-you prediction. Because implicit memory has a direct connection to your autonomic nervous system—the part of the brain that governs fight-or-flight—your body immediately gets flooded with stress chemicals. Your heart starts racing, your hands start sweating, you feel a general sense of doom. You have an overriding urge to get the hell out of there.
And no part of what I've just described requires your active knowledge or participation.
You don't have to consciously notice any similarities between where you are and where you were attacked. You don't have to think about Forest Tribe at all. In fact, even if you had brain damage that erased your episodic memory of Forest Tribe entirely, the rule would still function just fine. You would have zero idea why you wanted to flee the forest, but you'd feel a strong urge to hightail it back to your cave anyway.
That's the 'implicit' part of implicit memory, and it's why the system is so efficient. Once the prediction is activated, it catapults you straight into reaction without you have to co-sign anything. It's like you have a rule-governed auto-pilot constantly running in the background, which uses your nervous system to steer you toward some things and away from others. Meanwhile, you’re just thinking about what to forage for dinner.
Once you've got this rule about Forest Tribe stored in implicit memory, it's going to seem pretty much permanent. Someone from your tribe can tell you why Forest Tribe is actually awesome, and the rule won't change. You can practice empowering thoughts about how you’re safe from Forest Tribe, and the rule won't change. You can use deep breathing to calm your nervous system before going into the forest, and the rule won't change.
This indelible quality makes sense, given how important these predictions are. It wouldn't be ideal for them to change willy-nilly. A sabre-toothed tiger not eating you once shouldn't erase the rule Sabre-toothed tigers are a threat to life. But it also isn’t ideal if the rules couldn’t be updated at all. Acting on old information could also be lethal. So the rule-book for survival needs to be as stable and as accurate as possible.
That’s where memory reconsolidation (MR) comes in.
MR rewrites implicit memories, so that the existing prediction disappears and a new one takes its place. But this only happens under very specific conditions. Three things need to happen, in order, in a period of 4-6 hours.
1) The rule gets activated. So you'd have to be in a situation where Forest Tribe wants to kill you seems to apply, the implicit memory fires up, and you have that physical reaction.
2) You have an experience that contradicts or 'mismatches' the rule. For example: you see someone from Forest Tribe, so the prediction is activated. But then, instead of trying to kill you, the Forest Tribe member saves you from a sabre-toothed tiger! You've now had an experience that directly 'mismatches' the prediction Forest Tribe wants to kill you. Note: this mismatch is not enough to force an update. What it does is unlock the rule so it can be changed, should further conditions be met (see #3). It’s like you've now been given edit permissions on a google doc, but you haven't actually changed anything yet.
3) You have another contradictory experience (or a repeat of the original one), within a 4-6 hour window. Let's say you were injured in the sabre-toothed-tiger incident, and the Forest Tribe member helps you back to your cave. When you encounter this second mismatch, the rule updates. Your brain rewrites the original pathway containing the implicit memory with a new prediction, and it's as if the old one never existed. Your new prediction, Forest Tribe is helpful and not prone to killing you, seems self-evident— something you've always known to be true.
You’ll still have the episodic memory of the attack, but it doesn't create any kind of reaction in your body. It feels like something that happened a very long time ago. You have trouble believing you ever really felt afraid of Forest Tribe.
You have been memory-reconsolidated.
Now, notice how each of the steps required for MR acts as a kind of quality filter. By restricting change to moments when the rule is active, your brain can be sure that what’s happening in the present has actual relevance for the original prediction.
If you do have a contradictory experience when the rule is active, then it’s possible the rule might need to change—at which point the memory becomes editable.
But a single contradictory experience could also be a fluke or a one-off, so the criteria still haven't been met. It takes a second ‘mismatch’ within a few hours for your brain to accept that the rule is outdated and should be altered.
And at that point, it eradicates the original rule completely. The new information overwrites the old, and the old one is gone. Caput.
As way to reconcile the need for accuracy with the need for permanence for some stored knowledge, this is pretty genius. We’re used to thinking of the ‘primitive brain’ as an obstacle and a problem, but there’s nothing backwards or clunky about MR. The problem may have originated early in our evolution, but the solution is elegant as hell.
Now let's zoom back to the present. The threats we experience now are usually more emotional than physical, but the systems are exactly the same. Our brain is still busy storing predictions in implicit memory, and they're still piloting us around without our conscious knowledge.
Imagine if at some point, early on, you stored the rule, If you take yourself too seriously, people will laugh at and reject you. Imagine all the times across your life you were faced with opportunities to grow, only to be steered away from them by the AVOID AVOID DANGER signals flooding your system. And then imagine how exhausting it would be to try so many things to shift that fear of your own importance, only to have it sit there, unchanged and indelible, like a fate you were born to.
But once we understand how MR works, this whole soul-sucking struggle transforms. First, we know why the rule has been so unchanging despite all our efforts—and that it had nothing to do with how hard we tried or how much we wanted the change. Second, we can now fucking change the rule. We can escape that exhausting reality where we can’t seem to stay on our own side, and nothing makes it better. We can stop our implicit memories from steering us away from the very places we most want to go.
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