“It isn’t just about being long or short, it’s about function too.”

memory_types

If you clicked on this because of the title; you shan’t be disappointed.

There are many things that are different lengths but what makes up these functional pieces of body mass matters, too.

“Meeeemooorrieesss, in the corners ooff myyyyy miiiiiiiind…”

Memory is a function that we use everyday; well, obviously. We use it not only to remember people we like (or do not like), we use it to succeed (or fail) at school, we can be actively doing it (recalling) or not actively doing it (recognition). It is made up of many different sub parts, parts that can over lap and use the same neural map and also ones that do not.

To know this, we can refer back to the previous post about “why do we study Amnesia and brain damage?”, there is a great deal that the malfunctioning brain can show is.

So what are the different types of memory and what do they do for us, if anything?

These are the main guys:

Long – this is the stuff that we commit to memory; it is mainly autobiographical information about important events. It can contain anything that you specifically find interesting or important. It is made up of two systems known as declarative or procedural memory. This is the lifer guy.

Short – this is the stuff that we are thinking of committing to memory, or thinking about currently. It doesn’t require conscious recollection like long term memory so it requires less ‘thinking’. On average, a human with an average brain can recall 7 (+/-2) objects in a short period of time (30 or so seconds) but with maintenance rehearsal it can raise to 9 or so. He is a lingerer.

Working – this is the super fun guy. He is living in the moment and reacting to all the senses that he is being given (well modality specifically speaking :P). He processes sensory and linguistical content. Working and short term might sound the same, but they actual travel along different paths. Short term is always considering going long term and working memory is always living in the moment. Working memory holds, however momentarily, information from the outside world before it is either forgotten or encoded into long term.

These are the sub parts of the main guys, (think of them as the weird clingy on friends):

Declarative – This guy is super tight friends with long term memory. Declarative memory likes facts and knowledge. He is super tight friends with episodic memory and semantic memory. They keep all your conscious memories in a box under their bed (creepy? No. Just aware.)

Non-declarative – is all about the skills you learn. Non-declarative can play piano, ride a bike and all the motor functional things that we love to do. ND only has 1 friend (procedural memory) friends but that is ok, he is way too indie and cool riding on his bike and playing his saxaphone to care.

Implicit – this is just a nickname for declarative memory; they gave this nickname as declarative is all about what we don’t have to do; consciously remember. Things like making toast, or opening a water bottle; you don’t need to remember that stuff actively, implicit has your back and will help you not have to consciously recall every mundane activity you do through out your day.

Explicit – He is conscious. He is intentional. He is explicit memory. He is the personal diary that has every date written in. Appointment at the dentist at 2pm? Remembered it. the horrifying root canal you had at the dentist 6 months? Oh yes, Explicit remembers. The psychology theories? he Knows them. You make him remember cause he is a dirty little sub.

Episodic – Firefly? Got it. Charmed? Yup. Buffy?! You know it. This is the one where he remembers episodes not just from TV shows, but from your life. If any memory was going to write your autobiography, it would be this guy (and it would be as accurate as possible, perhaps with a few flares for colour).

Semantic – There is always a lover. A lover who remembers why we need to remember that Italian resturant that he took you to the night you dumped him. Semantic memory remembers. He is involved in the meaning that we know behind places, or events, as well as concept based knowledge (which is what we have learnt either through experiences or education).

Procedural – this is the functioning guy. You need something done? This is the one to go to. Procedural memory takes care of things like knowing how to drive a car and how many times you need to click the B button to get the double hit combo. He is all about action, Action, ACTION! He doesn’t need to be told how, he just does.

How does memory help us everyday though?

Well it can be little things like:

heuristics – this is the breaking down of problems into smaller, more manageable problems that we can use out implicit or explicit memory to solve. Games like the Tower of Hanoi are a good example of how heuristics are used, you can play it online here: http://www.mathsisfun.com/games/towerofhanoi.html

Expertise: So did you ever wonder how one person can look at a photo of a brain and now exactly where and what a healthy brain looks like, where as a amateur will do the same but need to look longer? Expertise is the reason for this; less conscious or explicit memory is used, because a lot of the necessary information has been committed to long term memory and so is procedural or implicit.

Forgetting is another major factor of memory; i do it often and usually at the cost of someone’s feelings (yes, i forget to turn up to things). Forgetting occurs the fastest shortly after we learn something and it decreases over time.

Wait; but then how does expertise work if we forget things over time?

Well, it is all a matter of importance. That which is deemed worthy is committed and that which is not is sent to the depths of hell via the episodic buffer. Forgetting, too, is slower in implicit memory. So, let’s say a surgeon has been practicing for years on how to cut that lesion just right so she/he gets it all; because it has become a procedural part of his memory it is harder to forget over time. Tulving et al (for a bunch of fun nerdy reads) showed that recognition worsened after one week, so really, when they tell you to regularly study the content and not cram before an exam they are not lying; there is experimental evidence.

Amnesia patients, again (these guys, giving everything and expecting nothing in return!) fail quite terribly on implicit memory tasks when the binding of information is required. this is known as the binding-of-item-and-content model. This model talks basically about how for something to be committed to memory it has to possess some kind of contextual relevance. Due to the hippocampus having a great deal to do with implicit memory and the binding model, and the fact that anterograde amnesia patients have this part of their brain damaged, they are unable to bind objects or contexts to memory and therefore do not remember new things. But, this (like a lot of things) can have a double dissociation, where one patient who suffers from anterograde amnesia will do poorly on task A and do really well on task B and the guy with the same amnesia does the reverse.

However!

(what this however?!)

However, using a process called repetition priming amnesia patients, and some brain damage patients also, are able to recall certain objects. This is when we repeatedly present a certain stimulus and this leads to a facilitated processing of its perceptual (sensory) features.

This is just a lithe touch on what memory is and has the capability to do.

stay tuned for Memory: No one likes a sequel.

S x

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