Hi, I'm Michael Corayer and this is Psych
Exam Review. In this video we're going to
go into more detail on short term memory.
So this is the second box in our three
box model proposed by Richard Atkinson
and Richard Schiffrin. In the previous
video we talked about sensory memory
which is all this information
coming in from our senses and one of the
things that we said about sensory memory
is that we can only focus our attention
on so much of this information and that
means that a limited amount of
information is going to be able to move
from our sensory memory into our
short-term memory. So one of the first
features of short-term memory that's
important is this idea that it has a
very limited capacity. There's only a few
things we can have in this short term
memory at once. So just how many things
can we have in our short-term memory at
once? Well based on research by George
Miller we have an estimate that we can
hold about seven items. This was
described in a paper he wrote called the
magical number seven plus or minus two.
So the idea here is that if you look at
people given different types of tasks
involving their short term memory, whether
it's remembering tones or lists of
digits or things like that, they can
remember about five to nine items
and once you get beyond nine items it
gets much harder and people start making
lots of errors. So this is where we get
this magical number plus or minus two
and I'll post a link in the video
description where you can read the
original paper from George Miller
written in 1956. Now you might think "well
I don't know, the other day I went to a
restaurant and the waiter remembered
everybody's order at the table without
writing it down and you know we ordered
more than seven items, so
this doesn't seem right. How is he able
to do that?" Well the answer is that it
depends on how you define items.
We can think of items as being single items or we could have
groups of items and the waiter is
probably grouping things. He's probably
using a technique called organizational
encoding. This refers to organizing
the information, looking for
similarities, things like that, finding
some sort of structure to the
information in order to reduce the
number of items that you're actually
recalling. So an easy way to demonstrate
this would be if I asked you to remember a
random list of digits. If I give
you 15 digits at once you'd probably
find this very difficult, if not
impossible to do but here I'm going to
give you a list of 15 digits and you probably
won't find it that hard. So if I said
"okay remember this number 5 5 5 5 5 4 4
4 4 3 3 3 221" you'd probably have no problem
recalling this number, holding it in
your short-term memory. Now it's 15
digits, how are you able to do this? Well
you're organizing the information, you're
looking and seeing that there's a
pattern here and so now you don't
actually have to recall 15 individual
items and so you're probably using a
type of organizational encoding called
chunking. This is where you sort of
break the information up into chunks and
if we look at this we say "ok there were
five 5s four 4s three 3s two 2s and
one 1". Now we only have five chunks to
remember and there's a nice pattern to
them that makes it even easier. You could
say maybe we have six items we have that
each chunk and then what the pattern is
but the idea is that's going to be
within the capacity of our
short-term memory so you'd be able to do
this. Whereas if these were 15 totally
random numbers and there wasn't any sort
of pattern to them, you'd find this much
harder you probably wouldn't be able to
do it. Alright so this demonstrates that
our definition of what exactly we mean
by an item can change. So the waiter is
probably going to organize this into
there were this many drinks and there were this many entrees and
there was one appetizer and
there were two desserts or
something, and so by sort of thinking
about the structure of the order they're
able to recall more than 7
individual items. Another
interesting part of short-term memory is
that it's not just for storage.
We have our sensory memory, just like
the raw information coming in. There's a
lot of it but we don't really do much
with it, other than we choose to pay
attention to certain parts of it. And
then we have our long-term memory which
has basically an unlimited capacity and
we can sort of draw on things from that
but it's in this middle section between
these that we're sort of working with the
information that we have. We're thinking
about things, we're changing them around,
manipulating the information and so this
brings us to an idea that there's sort
of a distinction between just the
short-term storage and a separate
process which is referred to as working
memory but they're both sort of
happening in this middle ground between
our sensory memory and our long-term
memory .So working memory refers the idea
that we can actively manipulate this
information. We can work with it
This means we have an
additional model to take into account
within our short-term memory because
it's not just storage, it's also
manipulation. So how does this
manipulation process work? Well, a model
proposed by Alan Baddeley and Graham
Hitch says that there's a few parts to
this process. First we have this idea
of a central executive and the central executive is sort of like the decision
maker. It decides what to do with the
information and in doing that it draws
on some different tools. So what are the
tools that the central executive can use?
Well one of these tools they refer to as
the visuo-spatial sketchpad. This is
sort of a fancy way of saying a mental
image that you sort of create in your
mind. You sort of bring it up on
this mental sketch pad. So if I
were to ask you to describe your bedroom
to me, you'd probably bring up a mental
image of it and then you'd use that, you'd
sort of look at it you, direct your
attention to this mental image and you'd
tell me about what you're seeing in your
mind, describe your bedroom to me based
on what you have in this visuospatial
sketchpad. Now another tool you might
draw on, if I asked you a different type of
question,
would be, you might draw on the phonological
loop. So what's the
phonological loop? Well if I asked you to
tell me, how many syllables are there in
phonological loop? How are you going to
answer that question? Well you're not
going to bring up a mental image, what
you're probably gonna do is you're gonna
mentally loop this sound, pho-no-lo-gi-cal loop, right? You'll say six syllables, you're
probably going to count on your fingers
while you do this. So what that's doing
is it's showing that there's a different
type of process you're using to
manipulate that information. You're sort
of mentally repeating the sound of it
rather than bringing up a mental image
so that means it's a different tool that
your central executive can call upon.
And you probably use this
phonological loop in a technique called
rehearsal and this is the idea that,
let's say I ask you to remember a phone
number, what you're going to do is you're
going to probably mentally repeat the
sound of that number over and over again.
That's called rehearsal and
essentially you can think of rehearsal
as re-inputting the information back
into your sensory memory, sort of
creating this sort of loop between ok
it's in my short-term memory but I know
it's only going to be there for
a short amount of time but if I mentally
repeat it then I sort of get to
start the process over again. It's like I
just, it's as if you've heard the
number again even though you might not
have to actually say it. You
don't have to actually hear it but you
mentally hear it again and you repeat
the number and then you get to the end.
Okay i'm going to start forgetting it, I
remember it just long enough to repeat
it again and then just long enough to
repeat it again and hopefully in the
meantime I either dial it or
find a place to write it down. So I'm
repeating it, repeating it, I know you
don't really have to remember phone
numbers anymore. When I was a kid you had
to do this much more often. Now you just
type it into your cell phone but you're
sort of repeating this process over and
over again right? That's this technique
called rehearsal and it relies on this
phonological loop. What you
probably also know about this is as soon
as that attention gets distracted, right,
that's a fundamental part of this loop
is you have to be paying attention to it
as soon as somebody asks you a question
or if somebody starts saying other
numbers, you're going to
immediately lose it. Either because
your attention got distracted or because
they started introducing
sounds of numbers into this loop and
that sort of made it impossible for you
to continue doing this. Now later Baddeley
introduced another possible tool
that this central executive can call
on and this is an idea called the, what
is it called, the episodic buffer.
This is just the idea that we must
also have some tool that helps to
integrate these other parts right? So you
have the visuospatial sketchpad and you
have the phonological loop, you've got
sights and sounds but you also
have a way to put them all together. So
when I tell you a story, you're probably
creating some mental images for some
parts of the story but there's also
you're hearing the sounds that I'm using
and you might sort of be mentally
repeating some of them, certain words
that I use to keep track of the story
and so you're integrating these
into a chronology that makes sense, right?
It's almost like a movie scene, right?
So this is sort of another tool that
must have to exist in order to
make that process happen. You don't
have this disjointed like, there were
mental images and there were sounds and
you know, you find a way to put them
together and in an order that sort of
makes sense into an episode, sort of a
narrative that you can follow. So
that's another proposed part of this
working memory system. Ok so that's the
idea that short-term memory is not just
a storage facility, it's also this
manipulation process, this working memory.
Now exactly how these two relate to one
another is still sort of up for debate
and people argue about "should we
consider, is there really a difference
between short-term memory and working
memory" or things like that but that's
beyond the scope of an
introductory course. But the important
thing to remember, no matter how exactly
these parts integrate with one another
we sort of have to agree that there is
this space between our sensory memory of
information coming in and our long-term
storage. There is this short 30
second section of time where we're able
to manipulate information and work with
it, we have some recall for it, we're kind
of storing it but not really compared to
long-term storage but there's definitely
this sort of gap between those two boxes.
Ok so I hope you found this helpful, if
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Thanks for watching!