In the previous video I introduced the multi-store model of memory, and in that video I said the long
term memory store is coded semantically, we store information according to what it means.
But when I think of a bike I do know semantically what it means to say bike,
the definition of the word. but I also remember how to ride a bike,
it's a muscle memory and that seems a different sort of long term memory from a semantic
memory, also I can think back and remember what happened the last time I rode a bike,
again that seems to be a very different type of long term memory. So let's explore the three types
of long term memory semantic, procedural and episodic in this psych boost video.
# Semantic, procedural and episodic long term memory
These are the three types of long term memory,
what I want to do is show you how we can define them as distinct processes
and look at some research and evaluations that support or contradict that they are separate.
The first distinction I want to make between the different types of long term memory,
is if we can put the memory into words. So if the type of long term memory is declarative or not.
Now with two types, episodic and semantic we would say that they are declarative,
so going back to my example, if you ask me do you know what a bike is I would say,
yea its a two-wheeled vehicle that you sit on and move by turning pedals. That's a semantic memory,
and I’ve described it in words. If you asked when was the last time you rode a bike I would say
I hired a bike last summer and rode it in the peak district, it was beautiful but it was the
hottest day of the year so a bit intense. You can see there a range of episodic points about
the last time I rode a bike, an episode from my life that I’ve been able to put into words.
But, if you ask me to describe in words how to ride a bike,
I get a little stuck, I mean obviously you sit on it, hold the handles and pedal, but that’s not it,
anyone trying for the first time with just those instructions is going to fall off.
Because riding a bike like other procedural memories is a nondeclarative implicit skill,
we can call it a procedural memory, also known as muscle memory. I can do it easily, but I
do it unconsciously after I have learnt the skill. Lets take another example, someone who knows how
to play guitar will have semantic memories of what a guitar is, episodic memories of
playing the guitar for others and procedural memories of how to actually play the guitar.
Application questions are common in this section, so you may want to take a moment to think of
other long term memories you can separate and classify as episodic, semantic and procedural.
So from those examples we can see we have two categories, declarative and nondeclarative.
Giving a quick definition for the two declarative memories,
episodic memories are our memories for specific events in our lives, and semantic memory is our
knowledge about the word, so facts and concepts. And to define non-declarative procedural memory
it's an unconscious memory of skills known as muscle memory.
But there are lots of differences between these types of long term memory that we should know and
will help us define them as separate processes. You dont need to remember absolutely all of these,
but you can pick a few to use if asked to talk about the differences between them.
So firstly I've already talked about declarative vs non declarative.
Next time stamped, this means, is the memory stored with reference to time and place?
Well with episodic yes, if I think back I have a sense of when that memory happened,
if I think back to when I was in school, when I started teaching or think of something that
happened yesterday each of those memories are associated with a particular time in my life.
When it comes to semantic memories, well not really, I know a range of facts but for the
vast majority of them I don't remember when I learnt the fact. I have a strong semantic
memory that Paris is the capital of France, but I have no idea when I learnt that fact.
Procedural memories are also not time stamped, I don't remember when I first learnt to tie my
shoes, but its a strong procedural memory. Both episodic and semantic memories can be
recalled consciously, I have a sense if I want to try to remember something that happened to me or a
fact, I think and try to bring the information into consciousness. But with procedural
memory I can perform it unconsciously. Episodic memories are autobiographical,
they are about me and my life experiences, when I think about them
I’m part of the memory. But neither semantic or procedural memories are autobiographical.
Episodic memories are easy to forget, semantic are more resistant to forgetting, and procedural
memories are very resistant to forgetting, I mean we even have the phrase it's like riding
a bike to describe how you can perform a skill well after many years when you haven't done it.
The level of emotion felt when coded influences the strength of an episodic memory,
how deeply the information is processed affects the strength of semantic memories,
so how many other bits of information we can link to it. And when it comes
to procedural how much practice we have had with a skill we have affects the strength.
Finally when it comes to brain regions. With episodic, the first coding seems to be in
the prefrontal cortex, but stored across the brain connected by the hippocampus.
With semantic memory one of the associated brain areas is the parahippocampal cortices,
and for procedural memories there is a role for the motor cortex and cerebellum.
#Evaluating types of long term memory To evaluate we want to look at evidence
that suggests that these three types of long term memory are truly separate. If we can trust that
research, and also are there any reasons to think they are not actually distinct.
Firstly we have research by Vargha-Khadem, this was an investigation of three young
amnesic patients who had all suffered damage to their hippocampus, but a nearby region called
the parahippocampal cortices were reasonably undamaged. It was found that all of these children
had significant episodic amnesia, but they were all able to attend school because their semantic
ability was largely unaffected, they learnt to speak and could recall factual information at
a level just a little under what was normal for their age. These results suggest that episodic
and semantic memories are separate processes that function using separate brain regions.
One of the most famous case studies in psychology is that of Clive Wearing,
after severe brain damage to his hippocampus caused by a virus he has retrograde amnesia,
meaning he can't remember episodic memories from before the brain damage, like his wedding
day, but he can recall semantic memories like the fact that he is married to his wife deborah
and still has the ability to play the piano a procedural memory.
He also has anterograde amnesia, he can't make new episodic or semantic memories. Very
interestingly under experimental conditions Clive and other amnesia patients like HM
when trained on a procedural skill can improve on that procedural skill, but they won't retain any
episodic or semantic memory of doing the skill. These case studies show the three types of long
term memory as separate processes, as each process can remain while the others are lost.
Now much of the research on types of long term memory use clinical case studies. This is an
example of idiographic research. These studies allow an in-depth investigation of memory in a way
that would be simply impossible in an experimental set up. However because they are individuals,
and unusual individuals at that, we may not be able to generalise findings on the types
of long term memory to other, healthy people. It may be that their brain damage is more
extensive than we can see. So there may be other reasons for their unusual experiences.
However there are reasons to argue that there may not be such a clear cut separation between
the different types of long term memory, firstly episodic and semantic memories
are both declarative, also episodic memories tend to become semantic memories over time.
Also there is a strong connection between procedural and semantic memory
as we are able to produce automatic language, this is the fact that we are
able to fluently talk using a wide range of semantic facts and concepts quickly
without having to consciously consider and recall every semantic fact.
have a go at this a real exam question on types of long term memory. if you are a psych boost
patron at the neuron level and above you can access a tutorial on psych boost .com.
in it I will talk you through a model answer for this question and general tips for everyone else
don't forget to subscribe so you don't miss the videos released right up to your exams,
and I will see you in the next psych boost video, the working memory model