Chapter 6: Memory - Ashton Southard

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Chapter 6


Three Processes of Memory


an active system that receives information from
the senses, puts that information into a usable form, and
organizes it as it stores it away, and then retrieves the
information from storage

Although there are several different models of how memory
works, all of them involve the same 3 processes

Getting the information into the memory system

Storing the information

Retrieving the information

Encoding: Putting Information In

The first process in the memory system is to get sensory information (ex.
Sight, sound, etc.) into a form that the brain can use


the set of mental operations that people perform on sensory
information to convert that information into a form that is usable in the
brain’s storage systems

Ex. When people hear a sound, their ears turn the vibrations in the air into
neural messages from the auditory nerve (transduction), which make it possible
for the brain to interpret that sound

Encoding is not limited to turning sensory information into signals for the

It is accomplished differently in each of the three different storage systems of

In one system, encoding may involve rehearsing information over and over to
keep it in memory, whereas in another system, encoding involves elaborating on
the meaning of the information

Storage: Keeping Information In

The next step in memory is to hold on to the information for
some period of time


holding onto information for some period of time

The period of time will actually be of different lengths,
depending on the system of memory being used

Ex. In one system of memory, people hold on to information
just long enough to work with it, about 20 seconds or so; but in
another system, people hole on to information more or less

Retrieval: Getting Information Out

The biggest problem many people have is retrieval


getting information that is in storage into a
form that can be used

Ex. You have taken an essay exam, later after the test is over,
you then remember several other things you could have said

Models of Memory: Information

Many researchers feel the
processing model
of memory is the most comprehensive and has been the most

Assumes the processing of information for memory storage is
similar to the way a computer processes memory in a series of
three stages

Focuses on the way information is handled, or processed,
through three different systems

The processes of encoding, storage, and retrieval are seen as part
of this model

Models of Memory: Parallel Distributed
Processing (PDP) Model

It is common to refer to the three memory systems of the
processing model as stages, but that implies a sequence of

While many aspects of memory may follow a series of steps or stages,
there are those who see memory as a simultaneous process, with the
creation and storage f memories taking place across a series of mental
networks “stretched” across the brain

Parallel distributed processing (PDP) model

processes are proposed to take place at the same time over a large
network of neural connections

Derived from work in the development of artificial intelligence (AI)

In the AI world, PDP is related to

(the use of artificial neural
networks to explain the mental abilities of humans)

Models of Memory: Levels
Processing Model

The information
processing model assumes that the length of time that a memory
will be remembered depends on the stage of memory in which it is stored

processing model

assumes information that is more “deeply
processed,” r processed according to its meaning rather than just the sound or
physical characteristic of the word or words, will be remembered more efficiently
and for a longer period of time

Ex. If the word

is flashed on a screen and people are asked to report whether
the word was in capital letters or lowercase, the word itself does not have to be
processed very much

only its visual characteristics need to enter into conscious

But, if those people were asked to use that word in a sentence, they would have to
think about what a ball is and how it can be used

They would have to process its meaning, which requires more mental effort than processing just
the word’s “looks”

Numerous experiments have shown that thinking about the meaning of something is
a deeper level of processing and results in longer retention of the word

Which Model Explains Which Aspects
of Memory

All of three models can be used to explain some, if not all, research findings
about memory

processing model

Provides a “big picture” view of how the various memory systems relate to each

how the “memory machine” works

PDP model

Is less about the mechanics of memory and more about the connections and
timing of memory process

processing model

The depth to which information is processed addresses the strength of those
parallel connections within each of the three memory systems, with strength and
duration of the memory increasing as the level of processing deepens

Although the information
processing model takes center stage for
explaining memory for now, it is important to remember the concepts of
the levels at which information is processed and the way that those processes
may take place

Processing Model:

3 Memory Systems

processing theory bases its model for human
though on the way a computer functions

Data are encoded in a manner that the computer can
understand and use

The computer stores that information on a disk, hard drive, or
memory stick

Then, the data are retrieved out of storage as needed

processing theorists were the first to propose
that there are three stages or types of memory systems

Sensory memory, short
term memory, and long
term memory

Sensory Memory

Sensory memory

the first stage of memory, the point at which
information enters the nervous system through the sensory systems

Information is encoded into sensory memory as neural messages in the
nervous system

As long as those neural messages are traveling through the system, it can be said
that people have a “memory” for that information that can be accessed if needed

Example: the “double take”

Imagine you are driving down the street, looking at the people and cars on either
side of your car. All of a sudden you think “Wait a minute, was that guy not
wearing pants?!” then you look back to check.

How did you know to look back? Your eyes had already moved past the possible
less guy, but some part of your brain must have just processed what you

This can only be explained by the presence, however brief, of a memory for what
you saw

There are 2 kinds of sensory memory that have been studied extensively

Iconic (visual) and echoic (hearing) sensory memories

Iconic Sensory Memory: Capacity

Iconic sensory memory

visual sensory memory, lasting only a fraction of a second



Partial report method
: presented subjects with a grid of letters and sounded either a
high, medium, or low tone after the grid of letters was taken away, which signaled
which row subjects were to report

The tone was sounded after the grid was taken away to that subjects couldn’t just
memorize one row of letters

Found that subjects could accurately report any of the three rows, meaning that they
entire grid was in iconic memory and available to the subjects

Thus, the capacity of iconic memory is everything that can be seen at one time

Rows of Letters

Tone Signaling

Which Row
to Report





Medium tone


Low tone

Iconic Sensory Memory: Duration


also found that if he delayed the tone for 1 second, subjects could
no longer accurately report letters from the grid

The iconic information had completely faded out of memory in that brief time

In real life, information that has just entered iconic memory will be pushed
out very quickly by new information, a process called

Research suggests that after only a quarter of a second, old information is
replaced by new information

Eidetic imagery

the ability to access a visual memory for 30 seconds or

Very rare condition, often called
photographic memory
, causes is unknown

People with eidetic imagery ability might be able to look quickly at a page in a
book, then by focusing on blank wall or piece of paper, “read” the words from
the images that still lingers in their sensory memory

More common in children and tends to diminish by adolescence or young

Iconic Memory: Function

Iconic memory actually serves a very important function in
the visual system

Remember that the eyes make tiny movements called

that keep vision from adapting to a constant visual stimulus,
so that what is stared at steadily doesn’t slowly disappear

Iconic memory helps the visual system to view surroundings
as continuous and stable in spite of the saccadic movements

It also allows enough time for the brain stem to decide if the
information is important enough to be brought into

Like the possibly pants
less guy from the example earlier

Echoic Sensory Memory

Echoic memory

the brief memory of something a person has just heard

Ex. The “What?” phenomenon

When you are reading, watching TV, or concentrating on something and someone
walks up to you and asks you if your ready for dinner. You sit there for a second or
2, and then say “What? Oh … yes I’m ready to eat now”

You didn’t really process the statement from the other person as he or she
said it, you heard it, but your brain didn’t interpret it immediately.

Instead, it took several seconds for you to realize that

1) something was said

2) it may have been important

3) you’d better try and remember what it was

If you realize all this within about 4 seconds (the duration of echoic
memory), you will likely be able to “hear” an echo of the statement in your

Like a kind of “instant replay”

Echoic Sensory Memory

Capacity is limited to what can be heard at any one moment
and is smaller than the capacity of iconic memory, although it
lasts longer (about 2
4 seconds)

Useful in conversations, allows a person to remember what
someone said long enough to recognize the meaning of a

And like iconic memory, it allows people to hold on to
incoming information long enough for the lower brain centers
to determine whether or not processing by higher brain centers
is needed

Term and Working Memory

term memory (STM)

the memory system in which information is
held for brief periods of time while being used

Like a sort of “desk” where people hold and work on information for a short time

If an incoming sensory message is important enough to enter consciousness, that
message will move from sensory memory to short
term memory

This is accomplished through the process of
selective attention

the ability to
focus on only one stimulus from among all sensory input

Dr. Donald E. Broadbent’s original filter theory of memory suggests a kind of
“bottleneck” occurs between sensory memory and STM

Only a stimulus that is “important” enough will be passed on to be analyzed for
meaning in STM

What is important is determined by a kind of “pre
analysis” in attention centers in the brain

Other stimuli are filtered out and will not reach consciousness

Also, when a person is thinking actively about information, that information is said
to be conscious and in STM

Term and Working Memory

But, it is difficult to use this original selective attention filter theory
to explain the “cocktail
party effect”

Ex. When you’re at a party somewhere and there’s a lot of noise and
several conversations going on in the background but you are still able to
notice when someone says your name

In this situation, the areas of the brain that are involved in selective
attention had to be working

even though you were not consciously
aware of it

Then, when that important bit of information (your name)
“appeared,” those areas somehow filtered the information into your
conscious awareness

in spite of the fact that you weren’t paying
conscious attention to the background noise

In the original theory, selective attention only operates after you are
consciously aware of a stimulus

Term and Working Memory

A newer theory, proposed by Dr. Anne M.
, suggest that selective
attention operates in a two
stage filtering process


stage: incoming stimuli in sensory memory are filtered on the basis of simply
physical characteristics

This is similar to Broadbent’s original idea

However, the filtering in this case is not an “all
nothing” event as in Broadbent’s theory,
rather it is a lessening or decrease (
) of the signal strength of those unattended
sensory stimuli when compared to attended stimuli

In other words, we lessen the signal strength of stimuli that are not important and not
attended to


stage: involves the processing of only the stimuli that meet a certain threshold
of importance

Attenuated stimuli are present at this 2

stage so something as subjectively important as
one’s own name may be able to be “plucked” out of the attenuated incoming stimuli

Ex. Selective attention is still working even when we’re asleep. This is why when
a mother is asleep she can be awakened by her baby’s cries but sleep through the
noise of the nightly train passing by (the noise of the train is unimportant and
has been attenuated while the baby’s cries are important)

Term and Working Memory

What happens when information does pass through the selective
attention filter and into STM?

STM tends to be encoded primarily in auditory (sound) form

That means that people tend to “talk” to themselves inside their heads

Although some images are stored in STM in a kind of visual
“sketchpad,” auditory storage accounts for much of STM encoding

Research in which participants were asked to recall numbers and
letters showed that errors were nearly always made with numbers of
letters that
sounded similar
than errors with those that
looked similar

Term and Working Memory

Some memory theorists use the term working memory as
another way of referring to STM

This usage is not entirely correct: STM has traditionally been
thought of as a thing or a place into which information is put

Working memory
is an active system that processes the
information in STM and is thought to consist of 3 interrelated

The central executive (“CEO” or “Boss”): that controls and

The visual “sketchpad”: for visual information

A kind of auditory “recorder”: for auditory information

Term and Working Memory

The central executive interprets visual and auditory
information and the visual and auditory information is itself
stored in STM

Ex. When someone is reading a book

The sketchpad will contain images of the people and events of
the particular passage being read

The recorder “plays” the dialogue in the person’s head

The central executive helps interpret the information from both
systems and pulls it all together

So in a sense, then, STM can be seen as being a part of the
working memory system

Term and Working Memory

For instance, if you see someone familiar at the mall

You pull that person’s name from your more permanent
memory and visualize that name along with the memory of the
last time you saw the person, almost like you’re viewing it on a
screen in your head

At the same time, you will hear the name in your head

The central executive pulls these different types of information
together and you are able to successfully greet the person

you see and hear this information is in STM


that allows this to happen and coordinates it all is
working memory

Capacity: The Magic Number 7

George Miller (1956): reviewed research on memory, including studies using a memory test
called the
span test

A series of number is read to subjects, then, subjects are asked to recall the numbers in order

Each series of numbers gets longer and longer, until subjects cannot recall any of the numbers in

Most everyone gets past the fist 2 sequences of numbers

But some people will make mistakes on the 6 digit span, about half will make mistakes on the 7
digit span, and very few people will be able to get past the 9 digit span without making any

This lead Miller to conclude that the capacity of STM is about seven items or pieces of

He called this the magic number 7, plus or minus 2 items (from 5
9 bits of information)

Current research suggests younger adults can hold 3
5 items of information at a time if a
memory strategy is not being used

When the information is in the form of longer, similar
sounding words or unfamiliar words,
that capacity reduces until it is only about 4 items

Capacity: Chunking


is a way to sort of “fool” STM memory into holding
more information than usual

It is a process of recoding or reorganizing information

If the bits of information are combined into meaningful units,
or chunks, more information can be held in STM

Ex. Remembering the digit span: 4,8,3,9,4,3,7,1,6,2

Would be easier if you grouped the numbers together into
chunks: 483

Instead of 10 separate bit of information, there would only be 3
“chunks” that read like a phone number

Term Memory: How Long Does
it Last?

Research shows that STM last from about 12
30 seconds
without rehearsal

After that, the memory seems to rapidly “decay” or disappear

The findings of one recent study with mice suggest that in order
to form new memories, old memories must be “erased” by the
formation of newly formed neurons

The hippocampus only has so much storage room

any of the memories formed there will be transferred to more
permanent storage in other areas of the brain

But, some memories, without rehearsal, will decay as new neurons
(and newer memories) are added to the already existing neural

STM: Maintenance Rehearsal

Maintenance rehearsal

practice of saying some information to be remembered over and over
in one’s head in order to maintain it in STM

Ex. Like repeating a phone number over and over again just long enough for you to dial it


person is simply continuing to pay attention to the information to be held in memory, and
since attention is how that information got into STM in the 1

place, it works quite well

Information will stay in STM until rehearsal stops, then the memory will rapidly decay and is

If anything interferes with maintenance rehearsal, memories are also likely to be lost

Ex. If you are trying to count a stack of dollar bills by reciting each number out loud while
counting, and someone asks you what time it is, you will probably forget what the last number
was and have to start all over again

Interference in STM can also happen if the amount of information to be held exceeds capacity
9 bit of information)

This is why it’s possible to remember the 1

few names of people you meet at a party, but as
more names are added, they displace the older names

FYI: a better way to remember people’s names is to associate the name with
omething about
the person’s appearance, this may help move the name from STM into more permanent storage

Term Memory

term memory (LTM)

the system of memory into which all the
information is placed to be kept more or less permanently

The capacity of LTM seems to be unlimited for all practical purposes

Think about it, would there ever really come a time when you couldn’t fit one
more piece of information into your head?

As for duration of LTM, there is a relatively permanent physical change in
the brain itself when a memory is formed

That means that many of the memories people have stored away for a long time
(even ones from childhood) may still be there

BUT, that doesn’t mean that people can always retrieve those memories, they
may be

but not
, meaning they are still there, but for various
reasons people cannot “get to” them

Ex. Its like knowing that there is a certain item on the back of the top shelf of the kitchen
but having no ladder to reach it, the item is there (available) but you cant get to it

Term Memory

Information that is rehearsed long enough may actually find its way into LTM

Most people tend to learn poems and the multiplication tables by maintenance rehearsal, also
known as rote learning


is like “rotating” the information in your head, saying it over and over again

But maintenance rehearsal is not the most efficient way of putting information into LTM,
because to get the information back out, your have to remember it almost exactly as it went in

Ex. Try this: what is the 15

letter of the alphabet?

Did you have to recite or sing the alphabet song to get to that letter? I bet so.

Although, many long
term memories are encoded as images, sounds, smells, or tastes, in
general, LTM is encoded in meaningful form

A kind of mental storehouse of the meanings of words, concepts, and all the events that people
want to keep in mind

Even the images, sounds, smells, and tastes involved in these events have some sort of meaning
attached to them that gives them enough importance to be stored long term

If STM can be thought of as a working “surface” or desk, then LTM can be thought of as a huge
series of filing cabinets behind the desk

Files are stored in an organized fashion, according to meaning

Files have to be placed in the cabinets in a certain organized fashion to be useful

LTM: Elaborative Rehearsal

Elaborative rehearsal

a method of transferring information from STM
to LTM by making that information meaningful in some way

The easiest way to do this is to connect new information with something
that is already well known

Ex. The French work

means “house.”

A person could try to memorize that (using maintenance rehearsal)by saying over and
over “

means house.”

But, it would be much easier and more efficient if that person simply thought, “

sounds like mason, and masons build houses.” That makes the meaning of the word tie
in with something the person already knows (masons who lay bricks to build houses)

The levels
processing approach discussed earlier proposes that
information that is more “deeply processed,” or processed according to
meaning will be remembered more efficiently and for a longer period of

This is true, elaborative rehearsal is a deeper kind of processing than
maintenance rehearsal and also leads to better long
term storage

Types of Long
Term Information

term memories include general facts and knowledge,
personal facts, and even skills that can be performed

Procedural (nondeclarative) memory is memory for skills

Because it usually involves a series of steps or procedures

Declarative memory is memory for facts

Because facts are things that are known and can be declared
(stated outright)

Procedural (Nondeclarative) LTM

Type of long
term memory including emotional associations,
memory for skills, procedures, habits, and conditioned

These memories are not conscious but are implied to exist because
they affect conscious behavior

Ex. Tying shoes or riding a bicycle

There is evidence that different areas of the brain are
responsible for procedural memories and declarative memories

The amygdala is the most probably location for emotional
associations, such as fear

he cerebellum in the hindbrain is responsible for storage of
memories of conditioned responses, skills and habits

Procedural (Nondeclarative) LTM

Evidence that separate areas of the brain control memory comes from studies of
people with damage to the hippocampus

This damage causes
anterograde amnesia

the loss of memory from the point of
the injury or trauma forward, or the inability to form new long


In one study, patients with this disorder were taught how to solve a particular puzzle

atients were able to learn the sequence of moves necessary to solve the puzzle

But, when brought back into the testing room at a later time, they could not
remember ever having seen the puzzle (or the examiner) before

Each trial was like the first one ever for these patients, as they were unable to store
the long
term memory of having been in the room or having previously met the

Yet, they were able to solve the puzzle even while claiming that they had never seen it

Their procedural memories for how to solve the puzzle were evidently formed and
stored in a part of the brain separate from the part controlling the memories they
could no longer form

Procedural (Nondeclarative) LTM

The patients in the previous study had the kind of memory problems
that people with Alzheimer’s disease have

Yet even people with Alzheimer’s disease do not forget how to walk,
talk, fasten clothing, or even shoes (although they do lose motor ability
because the brain eventually fails to send the proper signals)

These are all procedural, nondeclarative memories

They may not be able to tell someone that they know how to do these
things, but they can still do them

Alzheimer’s disease affects the hippocampus and the frontal cortex
(involved in decision making and planning) and eventually affects
other areas of the brain after it has progressed nearly to the end

In fact, it would be rare to find someone who has lost procedural

Literally, these are the kind of memories people “never forget”

Procedural (Nondeclarative) LTM

Procedural memory is similar to the concept of
implicit memory

memory that is not easily brought into conscious awareness

Because memories for these skills, habits, and learned reflexes are not also not
easily brought into conscious awareness

Ex. The fact that people have the knowledge of how to tie their shoes is
the fact that they can actually tie them

Such knowledge is in people’s memories because they use this information,
but they are often not consciously aware of this knowledge

Although procedural memories are very often implicit, not all implicit
memories are necessarily procedural

A memory from one’s early childhood of being frightened by a god may not be a
conscious memory in later childhood but may still be the cause of that older
child’s fear of dogs

Conscious memories for events in childhood, on the other hand, are usually
considered to be a different kind of long
term memory called
declarative memory

Declarative LTM

Declarative memory

type of LTM containing information
that is conscious and known

This type of memory is about all the things that people

Including general facts such as the names of the planets in the
solar system, that adding 2 and 2 makes 4, and that a noun is the
name of a person, place, or thing

Also includes what people know about the things that have
happened to them personally like what you ate for breakfast this
morning and what you saw on your drive to class

There are 2 types of declarative long
term memories

Semantic and episodic

Declarative LTM: Semantic

Semantic memory

type of declarative memory containing
general knowledge, such as knowledge of language and
information learned in formal education

This is the general knowledge that anyone has the ability to know

Most of this information is what is learned in school or by reading

Includes the awareness of the meanings of words, concepts, and
terms as well as names of objects, math skills, and so on

Type of knowledge use on games shows like Jeopardy

Semantic memories, like procedural memories, are relatively

But it is possible to “lose the way” to this kind of memory

Declarative LTM
: Episodic

Episodic memory

type of declarative memory containing personal information not
readily available to others, such as daily activities and events

Includes memory of daily life and personal history, like a kind of autobiographical

Ex. Certain birthdays or anniversaries that were particularly special, and childhood

Unlike procedural and semantic LTM, episodic memories tend to be updated and
revised more or less constantly

Ex. You can probably remember what you had for breakfast today, but what you had for
breakfast 2 years ago on this date is most likely a mystery

Episodic memories that are especially
, such as the memory of the first day
of school or your first date, are more likely to be kept in LTM

Although these memories may not be as exact as people sometimes think they are

The updating process is a kind of survival mechanism, because although semantic and
procedural memories are useful and necessary on an ongoing basis, no one really needs
to remember every little detail of every day

The ability to forget some kinds of information is very necessar

Declarative LTM:
Episodic & Semantic

Episodic and semantic memories are examples of declarative or

memory that is consciously known

Explicit memories are easily made conscious and brought from long
term storage
into short
term memory

The knowledge of semantic memories such as word meanings and episodic
memories such as what you ate for breakfast can be brought out of the “filing
cabinet” and placed on the “desk” where that knowledge becomes
, or

The difference between implicit memories (like how to ride a bike) and
explicit memories (like the names of all the planets) is that it is impossible or
extremely difficult to bring implicit memories into consciousness

Explicit memories can be forgotten but always have the potential to be made

Ex. When someone reminds you what you had for breakfast the day before, you will
remember and realize that you had that information all along


Declarative memory


Episodic memory

Events experienced by a

Semantic memory

General facts and knowledge

Procedural Memory


Motor skills, habits,
classically conditioned

LTM Organization

LTM has to be fairly well organized for retrieval to be so quick

Research suggests that LTM is organized in terms of related
meanings and concepts

In one study (Collins &
, 1969) had subjects respond
“true” or “false” as quickly as possible to sentences such as “a
canary is a bird” and “a canary is an animal”

Found that responses to sentences such as “canary is an animal” took
longer than responses to sentences such as “a canary is a bird”

Why? Because information exists in a kind of network, with nodes
(focal points) of related information linked to each other in a kind
of hierarchy

To verify the statement “a canary is a bird” requires moving to
only one node

But, “a canary is an animal” would require moving through
two nodes and, therefore, takes longer

LTM Organization

The results of this study lead the researchers to develop the
semantic network model

assumes information is stored
in the brain in a connected fashion, with concepts that are
related stored physically closer to each other than concepts
that are not highly related

LTM Organization

The parallel distributed processing model can be used to explain how rapidly the
different points on the networks can be accessed

Although the access of nodes within a particular category (ex. Birds) may take place
in a serial fashion, access across the entire network may take place in a parallel

Allowing several different concepts to be targeted at the same time

Ex. You might be able to think about birds, cats, and trees simultaneously

Maybe, the best way to think of how information is organized in LTM is to think
about the internet

A person might go on one website and from that site link to many other related sites

Each related site has its own specific information but is also linked to many other
related sites

And you can have more than one site open at the same time

This may be very similar to the way in which the mind organizes the information
stored in LTM