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Memory Storage


Memory Storage, and if you're just joining in right now, this is part of a little set on Memory Lessons. In the last lesson, I covered Memory Encoding, and here we're looking at Memory Storage. The guiding questions are, where are how do we process the information that we paid attention to, on a day to day basis.

What's going on in our different facilities our different modes of processing. The lessons after this look at, how do we actually recall the memories that we actually do form? So if there's one thing to know about memory storage, if you don't do anything else, if you just turn this off and walk away from this lesson forever, just know that there are three kinds of memory storage.

There are sensory, short term and Long-Term Memories, most of us are familiar with these terms short term, Long-Term Memories. Sensory is something you might be less familiar with and I'm going to go through each of these in more detail but this is just an overview slide. Sensory memories only last about one to two seconds, and they basically just provide a sense of continuity to our moment to moment experience.

An example, here, you lift up your foot to take a step, and you remember you're taking a step, which leads to footing your foot down. And then, you take the next step, without sensory memories, our actions and awareness would be extremely disjointed. We would feel like we're waking up from a dream every waking moment. And that's pretty much all you need to know about sensory memories.

The only other thing I would say is important to know is knowing how information goes from being a Sensory Memory into potentially getting stored and processed in the Short-term Memory. Because that's what happens, if information makes it past the sensory memory, it does become a short-term memory, or it has that potential. It's through awareness and selective attention, it has to do with as you're walking through space, what are you paying attention to.

We're constantly bombarded with stimuli and we pay attention to just a little bit of it, most of it flies by the radar. The information that we do pay attention to, that has the potential to become stored in our short-term memory. After that we have the Short-Term Memory, which is also called the working memory. And it has a duration of about 15 to 30 seconds, I think of our short term memory as kind of like a very unstable to-do list that we kind of hold in awareness for a limited period of time.

So, for an example, let's say you're making a cake, you're mixing the batter, you read the first three ingredients add them, then go back to the book and app to read the next three. I mean some people might try and store a whole recipe into their longterm memory, but overall it's a lot more efficient to just remember these ingredients for a very limited period of time.

A few characteristics of short-term memories is that they are Well, they're limited in capacity, a maximum of 4 to 9 items is what can typically be stored in working memory. They're limited in duration, so 15 to 30 seconds is about how long you can keep that thought stored in your working memory. And if that thought is still there after 15 to 30 seconds, that probably means you've been doing some kind of mental rehearsal of that information, and it´s already made it to your long term memory.

And example of that would be, say you want to go to the store, you just want to pick up four items, and you're kind of rehearsing to yourself as you´re driving What those four items are, that's actually now in your long term memory, cuz it's been there for longer than 30 seconds. Short term memories are primarily acoustic, when we're using our short term memory we often mutter or talk out loud or just kind of hear in our mind a voice repeating information.

And short term memories are vulnerable to distractions, you get startled by the doorbell as you're kinda rehearsing these ingredients in your mind, and then you can't remember was it half a teaspoon or one teaspoon of salt? Short term memories become long term memories through various kinds of rehearsal. If you repeat this to yourself over and over again for a long enough period of time, that's a type of rehearsal and after 30 seconds of that, it's actually landed in your long term memory.

What happens during this stage is that the memory moves from the hippocampus which is the seat of the short term memory and it starts to become processed this by your neocortex which is where your long term memory's are stored. And long term memories can last indefinitely if the brain isn't damaged, that doesn't mean all memories can be accessed easily but that's because we can't retrieve them, it's not because they aren't there.

Okay, so I want to talk about Broadbent's Filter says that stimuli is selectively attended to as we go through our days and it's processed at varying levels of depth. We have tons of information coming into our sensory memory all the time. And then, some of that becomes short term memory through as you remember selective attention. So an example of this is, say you are sitting at work you're doing what ever you are doing, working or checking your email, and the people next to you are having a conversation.

They are not super next to you, you can kind of hear your word, their word if you try, but your not paying attention you don't even really know what they're talking about. All of a sudden one of them says your name in their conversation and suddenly it's like that name jumps out to you, it sounds louder, it's clearer you're paying attention.

So that's an example of Broadbent's filter, we selectively attend to stimuli and it's not necessarily conscience. Like the example with your name you don't suddenly become aware because you're trying to become aware it just jumps out at you. And you can even think of it as though each memory is kind of like a funnel for the next stage.

Some sensory memory do becomes short term and then some short term memory becomes the long term memories. What's really interesting is actually this April 2017 research that was released that say there are some short term memories and long term memories, that appear to form in parallel rather than sequentially and specifically these are emotional memories, memories that involve fear.

Amygdala activation can undergo the first stages of longterm memory formation in the neocortex before the hippocampus is even sending the signals, and so. In this case, they're working in parallel, and if you think about this from like a survival or evolutionary perspective it makes sense that if something is very frightening to us it might be in our best interest to store that information as a long term memory as quickly.

And as effectively, and as strongly as possible, so that we can avoid dangerous situations in the future. Emotionalized memories tend to be very strong in general, especially when they are tied up with fear, so here is an overview, just kind of a summary of this remember. Sensory memories become working memories via selective attention like broad bands filter, working memories become long-term memories via rehearsal.

And then, of course there are just those few examples where it looks like short-term and long-term memories are formed and parallel, it's not that one becomes the other. The last thing I'm gonna cover here are the two major groupings of long-term memories, looking at the third stage, more than 30 seconds, implicit and explicit. Implicit memories are the skills that we know, but we can't really easily articulate, they're also called procedural memories, those are often used as synonyms for one another just like working memory and short-term memory are synonyms and an example of this is riding a bicycle.

We have, if we've ever learned to ride a bike, we have memories, body type memories of how you do that. They're in our long-term memories, and it would be very difficult to try and describe in great detail how exactly we rotate our ankles or wrists, and how we grip the handle bars, and so on, and so forth, right? It's not something that we can easily articulate, and yet, people can usually access that memory without having to re-learn the steps all over again.

Explicit memories are also called declarative memories, so those are synonyms for one another. And there are two kinds of explicit memories, episodic, these are memories about something specific that happened such as a bike trip that you took five years ago, it was an incident, an event. And then, semantic explicit memories are more along the lines of what we usually think of when we think of memory, such as being able to memorize and talk about the physics laws that enable bikes to work in the first place.

So procedural memories are like skills, episodic are kinda like stories, and then semantic that's just information. One last thing is I wanna clear up a little bit of confusion about short term memories, really drive this home. Remember that short term memories are working memories, really do just have a duration of about thirty seconds.

If at one point in your life you knew something for longer than thirty to forty five seconds that information was stored as a long term memory. Some examples where people often use the term short term memory when really they're referring to the long term memory would be cases such as this. The content that you crammed for right before a midterm and then you can't recall it when its time to study for finals, that information still is in your long term memory.

Now you might have to go back in and reinsert it and re-encode it, because you might not have encoded it in ways that make it easy to retrieve. But the information is there, it's just hard to access, the hotel room, from a vacation you took three ago. Think about how many of those their are, all the different room numbers you've ever had or just what you had for lunch yesterday.

And in the next lesson, we'll talk about retrieval, which is what I think is, when we talk about memory, that's mostly what we're usually talking about. How do you actually get the information back into your awareness after you've stored it?

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