Download Models of memory

Study Design Dot Point: Comparison of
models for explaining human memory
The Atkinson-Shiffrin
Multi-Store Model of Memory
A model of memory is used
to represent, describe and
explain memory, its
components and processes.
Often diagrams are used to
represent the movement of
information from one store
to another.
A Diagram of the Atkinson-Shiffrin Model
You should be able to visualise this model in your
visuo-spatial sketchpad and reproduce it at will!
According to the Atkinson-Shiffrin model,
memory has three components. Each
stores, encodes and processes information
in varying ways:
• the sensory register Sensory information that
is not attended to is lost for ever. Information
attended to in this register passes to ...
• the short-term store Holds limited information
from the sensory register and information
retrieved from the long-term store. Rehearsal
allows storage in ...
• the long-term store Permanently held
information, in a store with essentially
unlimited capacity
Structural features of the
Atkinson-Shiffrin Model
❖
This means the permanent, built-in or fixed features of
memory
❖
Structural features include:
❖
the three different stores
❖
the function of each store - that is, the role it plays
in human memory
❖
each component’s storage capacity
❖
the duration of time that information is held
Control features of the
Atkinson-Shiffrin Model
❖
These vary from individual to individual - we can choose.
❖
For instance, you can choose what you pay attention to
and therefore what passes from the sensory register to the
short-term register
❖
Rehearsal is also under individual control; it determines
how long information is held in the short-term store and
whether it is passed on to the long-term store
❖
Retrieval is another control process. The method
we use to access information is chosen by us.
❖
SUMMARY: The Atkinson-Shiffrin Model is based on
and supported by substantial research. It is still useful in
understanding memory, but it has been developed and
challenged.
❖
There are now believed to be several sensory registers,
possibly one for each sense.
❖
Short-term memory is now considered to be more complex
than it was believed to be by Atkinson and Shriffrin. It is now
seen as a number of separate, interacting components,
not a single store.
❖
Long-term memory is no longer seen as one system, but as
several sub-systems or stores - procedural (implicit),
declarative (explicit), which includes episodic and semantic,
etc. There is more focus now on how we not only retrieve
memories but reconstruct them in the process.
Criticisms of the
Atkinson-Shiffrin Model
❖
The concept of the sequenced flow of informa5on through sensory, STM and finally LTM is now believed to be more complex than proposed by Atkinson and Shiffrin. Some believe this model was too straighEorward and linear in its descrip5on of memory processes.
❖
There is now evidence for the concept of a separate sensory register for auditory informa5on and for other senses.
Limitations of Atkinson and
Shiffrin’s Concept of STM:
❖
❖
Neuroimaging techniques have matched STM and other stores with physical loca:ons in the brain, demonstra:ng that STM is much more complex than Shiffrin and Atkinson realized.
The Atkinson-­‐Shiffrin model tended to overemphasise the role of maintenance rehearsal and overlook elabora:ve rehearsal.
A PET scan showing the
active brain of a person
doing a STM task
See the discussion of Baddeley
and Hitch’s Working Memory
Model for the source and
meaning of this scan.
Limitations of Atkinson and
Shiffrin’s Concept of LTM:
❖
LTM is now believed to have different subsystems, such as episodic and procedural; each of these processes and stores different kinds of informa:on. ❖
The role of implicit memory is perhaps not emphasised adequately in this model.
❖
Informa:on is not always simply retrieved from LTM and available for use exactly as it was originally stored; it has been shown that we reconstruct memories, that is, fuse a remembered event with newer informa:on, changing the “memory” subtly in the process.
More about Sensory Memory
the first store of memory is
fleeting in d u r a t i o n, but
huge
in capacity
Be careful not to confuse these two
concepts of duration and capacity!
Duration versus
Capacity
• Duration means the length of
time that the memory is held
in a memory store
• Capacity means how much
can be held at any one time
SENSORY MEMORY
is brief or fleeting in duration
but virtually unlimited in capacity
Echoic
memory
Iconic
memory
Examples of sensory registers
Sensory Memory
holds an exact copy of sensory input
has a register for each sense
the t wo registers that have been most
extensively researched are:
ECHOIC
ICONIC
ECHOIC MEMORY
Brief auditory memory which lingers for 3-4 seconds
This is long enough for us to be able to link
impressions of sound with the next syllable or word
we hear
When we pay attention to the sounds (in order to
transfer them to short-term memory) we are able to
make sense of the sounds as a word or the words as
a sentence
Echoic memory thus makes speech perception
possible
ICONIC MEMORY
STORE FOR VISUAL SENSORY INFORMATION: Even
more fleeting than echoic memory, this sensory
register holds a vast amount of visual information for
about a third of a second. Your text says - 0.2-0.4 of
a second.
Sperling’s studies showed that people actually held
all the information he projected on a screen, but lost
it faster than they could report it. To overcome this
difficulty, he devised a research method that
demonstrated both the vastness and the briefness of
this memory store.
MOVING TO THE NEXT STAGE:
Sensory memory is huge in capacity, but fleeting
in duration. One advantage of this is that we can
quickly filter out extraneous matter.
We don’t have to remember everything we see, hear
and experience. In fact, it would be
we did.
overwhelming if
The only way we can keep, hold on to, preserve and
hope to prolong sensory memories is through
ATTENTION. Only the material we attend to
passes into short-term memory.
The usefulness of sensory memory in allowing
us to filter out overwhelming detail...
How could you cope with life if you
couldn’t filter out the extraneous details?
Short-Term Memory
temporary storage (18-­‐20 seconds without rehearsal)
(Note that Atkinson and Shiffrin believed this period was 30 seconds in their model. See your text, p.304, under DURATION OF STM for clariOication of this point.)
limited capacity (7 plus or minus 2 bits or chunks)
often encoded phonentically (according to sound)
very sensitive to interference
information is lost though decay (fading) or displacement (being pushed out by new information)
The distressing
shortcomings of
STM
For instance, as a youthful sales assistant in the shoe
department at Myer, I would be asked by three
different customers to get an 8 in the style Ecstasy by
Jane Debster, a 7 in Cargo by Sandler and a 40 in 19203
by Stuart Weitzmann.
Should I have been able to hold this amount of
information in my STM?
Yes! That’s actually only 6 pieces of information, chunked (or
9, if you count the brands). I would enter the rabbit burrows
of the back of the department, muttering to myself
(maintenance rehearsal, vocal or sub-vocal).
Then the manager would say, “Roslyn, can you
work tomorrow from 5-9 and on Saturday from
1-5?”
“Sure I can!” I would cry. Then I would realise that I
could no longer remember which size I needed to
get in which shoe. I would have to go out and say to
the customers:
“I’m sorry. I am an idiot and have forgotten
what you asked for.”
What I really said:
“Forgive me, although I had successfully
chunked your request for shoes and was
rehearsing it to keep it in my short-term
memory until I found what you wanted, my
maintenance rehearsal was interrupted and the
information in my STM was consequently
displaced. It’s not my fault, it’s a well-known
psychological phenomenon.”
Increasing the capacity of STM through chunking
Extending time in STM OR
moving material into LTM:
Rehearsal: Any activity that allows information to be
retained in memory and retrieved when required: may
be verbal, vocal, non-verbal, sub-vocal, mental imagery.
Maintenance rehearsal: Simple, rote repetition of
information. This needs to be attended to consciously –
should not just be meaningless repetition.
Elaborative rehearsal: Involves linking new information
in a meaningful way with information already stored in
long-term memory. More active and more effective than
maintenance rehearsal, this ensures that information is
encoded well.
Elaborative Rehearsal
Any activity that adds meaning to
information allows it to be encoded
semantically, which is how LTM is
organised.
For instance, self-referencing is a form
of elaborative rehearsal. You tie new
information that you need to learn to
something that is personal and
meaningful to you, as I did with my shoe
example.
Well-encoded information is easier
to retrieve because there are many
ways in which you can access it in
your long-term memory.
Using a diagram
allows elaborative
rehearsal of a
concept.
Elaborative Rehearsal
More Elaborative Methods
Work out an analogy, a rhyme, an acrostic, a
story, to help you remember something. Think of
examples, work out synonyms you could use to
describe a concept, change a teacher’s description
into your own wording, draw a concept map, a
diagram, a picture or set of symbols. The more
you work on the information, the easier retrieval
will be.
On the neuronal level, there will be more
connections bet ween neurons that will increase
the efficiency of communication in your brain.
Elaborative Rehearsal
More Methods
Mnemonics add meaning to information and therefore qualify
as methods of elaboratively rehearsing material.
ROYGBIV, EGBDF, the Hippo Campus is on Memory Lane, a
stalactite hangs on tight, a stalagmite might get there...
Serial Position Effect
Serial position effect: Participants show better recall for items at the beginning and end of a list than in its middle.
Primacy effect: Items near the beginning of a list are recalled better than other items.
Recency effect: Items near the end are recalled better than other items.
Serial Position Effect
An Explanation of Serial
Position Effect
!
!
The early items are rehearsed more and therefore have a greater chance of being transferred to LTM.
!
!
The ;inal items displace the middle items in STM and are still there at the end of the task, allowing them to be recalled well too.
This explanation is
supported by...
The effects of delayed recall on the graph are
shown below.
When participants in a recall experiment of this
kind are delayed in recalling for 30 seconds, the
recency effect was lost. The 30 seconds extend
beyond the duration of STM.
Note the red line
The primacy effect remains.
!
Baddeley and Hitch’s Model of
Working Memory
Baddeley and Hitch believed that the
STM store in the Atkinson-Shiffrin
model was too simplistic.
They emphasised in their model of
working memory that STM was not
simply a passive store of information
but a set of active processes that
manipulate information.
Baddeley and Hitch’s
Model of Working Memory
Baddeley and Hitch
emphasised that STM
is working (i.e.
processing and
manipulating), not just
storing and rehearsing.
Their model focused
on how working
memory supports
complex and
important cognitive
activities, allowing us
to visualise, store
sounds, make
decisions and
coordinate tasks.
General Information about Baddeley and
Hitch’s Working Memory Model
The central executive, phonological loop and visuospatial sketchpad are separate and can function
relatively independently.
But they also interact.
The phonological loop and visuospatial sketchpad are assumed to be
sub-systems of working memory,
whereas the central executive is
assumed to be an “attentional
controller”.
VISUO-SPATIAL SKETCHPAD
This is one component of
the Baddeley-Hitch model of
working memory
The visuo-spatial sketchpad
stores and manipulates visual
information
This allows you to visualise a
room and store in memory
the location of objects in
space
Visuo-Spatial Sketchpad
A mental workspace for
storing and manipulating visual
and spatial information
For instance, the tasks to the
right require you to visualise
and rotate objects,, or to
visualise a 3D object whilst
looking at a 2D one. Both
require the use of your visuospatial sketchpad.
Can you think of some everyday
tasks that require visualising
and the location/manipulation
of objects in space, using what
we might call your “mind’s eye”?
Can you form a cube by cutting
out and folding this shape?
Visuo-Spatial Sketchpad
Example: When you look for something
in your crowded locker, and can picture
in your mind exactly where it is, you are
using your visuo-spatial sketchpad.
Some more uses for your
Visuo-Spatial Sketchpad...
Finding or describing the location of
a book or object in a crowded room
Picturing internally
the location of your
friend in the
classroom
Going straight to that
outfit you need for a
party, even though
your cupboard is a
mess
Phonological Loop
Another component of Baddeley and Hitch’s model
Also called verbal working memory
Temporarily stores a limited amount of verbal,
speech-like information
Verbal information is held in a sound-based or
phonological form
You hold the information through sub-vocal
maintenance rehearsal; without it, you could only
hold about 2 seconds’ worth of information
From Baddeley,
Your Memory: A
User’s Guide (in
library), p. 47
This PET scan uses the rate of oxygen consumption in the
brain to reveal which areas are most strongly involved in
which mental activities. This brain scan suggests that two
areas are strongly activated by phonological short-term
memory, one involved in storing the memory (A) and the
other with rehearsal (B). (Paulesu et. al. 1993)
Phonological Loop
Research evidence suggests that the
phonological loop is important to language
learning, both in acquiring one’s native
language as a child and in learning the
vocabulary of a foreign language as an adult.
A Word on Multi-Tasking
The phonological loop and visuo-spatial sketchpad both have
limited storage capacity, but the capacities of each
component are assumed to be independent of each other.
Reaching the limits of one component does not
affect the capacity of the other component.
Dual-task
experiments
have shown that
people can do two
tasks at once,
maintaining
information in one
sub-system whilst
carrying out a task
requiring the other.
For instance, last year I found that I could paint a
portrait of my daughter while listening to German
podcasts, but I couldn’t listen to German and type an
email in English. What are some tasks you can do
simultaneously that don’t interfere with others? What
are some tasks you cannot do at the same time?
Central Executive
Another component of the Working Memory model
Monitors information and
selects which information to
pay most attention to
Shows the dynamic nature of
working memory, as opposed to
the “Short-Term Store” in the
Atkinson-Shiffrin model
Though limited in storage
capacity, the central executive is
an active cognitive mechanism
Central executive
Integrates information
from other components
and from LTM
Involved in all our
thoughts, feelings and
decisions in normal
waking consciousness
Central Executive
A final summary
According to Baddeley, the central executive
controls the phonological loop and the visuospatial sketchpad, which he refers to as “slave
systems”. It relates them to long-term memory.
Your text: “In everyday life, the central
executive is involved in planning and goalsetting, helping you decide what to do next, or
what not to do. When you change your mind
about what to do, it will coordinate task
switching, enabling you to change tasks
smoothly while it controls the flow of
information within and between the working
memory and LTM systems.” (p.318)
Episodic Buffer
A late entry to the model
Baddeley thought
that his model did
not explain how
working memory
links with LTM.
Consequently, he
added a fourth
component in 2000,
the episodic buffer.
Episodic Buffer
A sub-system of
working memory that
enables the different
components of
working memory to
interact with LTM.
Assumed to be a
limited-capacity
storage system that
holds about 4 chunks
of information.
The episodic buffer is a bit like a mental
workbench for cognitive activities
Episodic Buffer
Baddeley called it this
because he believed that
this component can pull
together separate streams
of information from
elsewhere in working
memory and LTM and
then combine them into
scenes or episodes, like
memories of a story or
movie scene.
Episodic Buffer
Baddeley called it a “buffer” because it provides
a temporary working space where
information can be edited, reordered or
reorganised in a meaningful way.
See the example of how the four components of the
working memory model might work in everyday life
(p.319).
How do all these components work together to allow
you to manage a complex, muli-faceted task?
❖
You are cooking dinner.
❖
Your daughter or little sister spills her milk on the floor.
❖
The phone rings. It is your best friend, wanting to tell
you urgently how she/he hates her boyfriend/girlfriend.
❖
What is your working memory doing? How are all the
components involved?
Strengths of Baddeley and Hitch’s model
of working memory
❖
The model fits with our
experience of everyday life.
❖
For instance, counting the
number of windows in
your house requires the
visuo-spatial sketchpad;
the sub-vocal counting
requires the phonological
loop; this would be
coordinated by the central
executive.
Strengths of Baddeley and Hitch’s model
of working memory
❖
A considerable amount of
research evidence, including
experimental evidence and even
brain scans showing different
parts of the brain at work,
supports the components
Baddeley and Hitch suggested.
❖
For instance, experiments in
which participants successfully
did dual tasks suggest that there
is indeed a component focused
on visual tasks and another
focused on sound-based tasks.
Concerns about the
Baddeley-Hitch model
❖
It is difficult to test and
verify the role of the
central executive.
❖
It is difficult to quantify
what is meant by “limited
capacity”.
❖
The episodic buffer still
requires more research and
explanation.
Craik and Lockhart’s
Levels of Processing Theory
❖
Attention is vital to the
encoding of memories,
but not all attention is
created equal.
❖
You can pay attention in
different ways or focus on
different aspects of the
stimulus input.
❖
According to Craik and
Lockhart, different rates of
forgetting occur because
some methods of encoding
create more durable
mermory codes than others.
Craik and Lockhart’s
levels of processing theory
Encoding: The process of converting information
into a useable form or “code” so that it can enter and
be stored in memory.
According to Craik and Lockhart, remembering depends on
how information is encoded.
If you encode only by paying attention to basic features,
you will encode at a shallow level. If you encode by
making new associations, this information will be
encoded at a deeper level, which results in better recall
(Plotnik, p.249).
An example...
Shallow processing: It’s tall,
grey, crooked.
Physical properties detected.
Intermediate processing: It’s the
Leaning Tower of Pisa in Italy.
Recognised and named.
Deep processing: Galileo
reputedly used it for an experiment;
tourists use it to create visual
illusions; maybe the foundations are
shallow...
Meaningful associations created.
The shallow, intermediate and deep processing
student... (not a serious page)
Harrison and Richard are
naturally in the deep
category (despite the
crocheted blanket)
Shallow processing student: Notices what the
teacher is wearing. Knows where friends are sitting.
Complains if teacher doesn’t write neatly.
Intermediate processing student: Copies notes.
Reads textbook. Writes definitions.
Deep processing student: Uses own wording when
possible for notes. Reads beyond textbook. Thinks
up analogies and examples, designs diagrams,
draws concept maps, asks probing questions
(teacher struggles to answer), makes up questions
and tries to answer them, encodes meaningfully;
neural connections abound in his/her subtle
brain...
Your own example of
variations in processing...
Choose a topic, theme or experience and try to imagine how
you could encode it in a shallow way, at an intermediate depth
or deeply. Share your ideas with the class. Here are some
possibilities:
a problem or formula in mathematics
models of memory
learning a poem or song
remembering a group of people’s names
remembering a text for English/English Literature
Criticisms of the Model
It is difficult to quantify “depth of processing”.
How can this be measured in a truly objective
way?
Baddeley has pointed out that the logic of this
theory might be considered circuitous, making it
difficult to test. To test whether deep processing
improves long-term memory encoding and
retrieval, one could see whether a person has
remembered something. If he has, then you
could deduce that he had processed it deeply.
Questions and Answers
ONE
What role does
attention play in
Atkinson and
Shiffrin’s theory?
How has this been
changed and
developed by
Baddeley and
Hitch?
Questions and Answers
ONE
In the Atkinson and
Shiffrin model, attention
is what ensures the
information in the fleeting
sensory register to get into
the short-term store.
Once in the short-term
store, information that is
attended to through
maintenance rehearsal is
kept there through rehearsal
or encoded for storage in
LTM.
The role of attention is more
complex in the Baddeley and
Hitch model, which focuses on
working memory as a dynamic
version of STM.
The central executive is the
“attentional controller” which
determines what will be attended to
and what will not. It directs its
“slaves” (the other components) to
focus on certain aspects of the
incoming sensory information.
This kind of attention is viewed as
more active, complex and multifaceted than in the earlier model.