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What is memory? To a psychologist, memory is
learning that has persisted over time,
information that can be stored and retrieved.
How does memory work? One analogy would
be to compare our memories to a computer.
Information must be encoded (into brain), then
it must be placed in storage (retained) and
lastly it must be retrieved (get it back out).
Our memories do not work exactly like a
computer. Our memories are more fragile and
less literal. A computer processes speedily and
in sequence while our brains are slower but
does many tasks at one time.
An early model of memory formation was
developed in 1968 by Richard Atkinson and
Richard Shiffrin. It is known as the three
stage processing model of memory.
 1. We first record to-be-remembered
information as a short lived sensory memory
 2. From there we process information into a
short term memory bin, where we encode it
through rehearsal
 3. Finally, information moves into long term
memory for later retrieval.
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A newer modified version of this model includes two
important new concepts:
1. Some information skips the first two steps and is
processed directly and automatically into long term
memory, without conscious awareness
2. Working memory, is newer understanding of the
second step. This newer info focuses on the active
processing of information in the second stage. The
brain cannot possibly process all the incoming stimuli
at the same time, we focus our attention on certain
stimuli (the novel or important). We process these
incoming stimuli along with info retrieved from our
long term memory, in a temporary working memory.
Working memory associates new and old information
and helps us solve problems.
So how do we encode information?
 Automatic processing: the human brain
engages in parallel processing, doing
many things at the same time.
 Because your brain multi-tasks, it must
resort to parallel processing. You process
some things by automatic processing,
without even thinking about it.
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We automatically process information about certain
things. For example:
Space: encoding information based on where it is:
Remembering information based on where you
wrote it on a page
Time: while going through your day you
automatically encode the sequence of your day:
helps you remember where you left your coffee cup
Frequency: you without thinking remember the
frequency of things that occur in your day
Well-learned information: you automatically
recognize and process information that you know
well: words on a billboard or sign
Encoding of information through effort and
attention. Effortful processing often
produces accessible and durable
memories.
 Encoding can be aided through rehearsal.
Rehearsal is conscious repetition.
 Hermann Ebbinghaus was an early
researcher in the field of verbal memory.
 He studied his own learning and forgetting
of novel verbal information.
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His experiment involved learning strings of
unrelated letters. He would choose a list of the
random syllables, read aloud and practice
them, then test himself.
The day after learning the list, he would try to
recall the syllables. But he could recall very few
of them. Were they forgotten?
Ebbinghaus continued. He would change the
number of times he rehearsed the list and then
measure the time it took him to relearn it the
next day.
He discovered that the more repetitions on day
one, the shorter the relearning time on day 2.
From Ebbinghaus, we get one of the
simple principles of effortful processing:
The amount remembered depends on
the time spent learning.
 For novel verbal information, rehearsal ,
effortful processing, does improve
memory performance.
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Spacing effect: We retain information
better when our rehearsal is spaced out
over time. Many studies have shown that
spacing learning times is beneficial.
 Massed practice can produce quick
learning but distributed study time produces
better long term recall.
 Henry Bahrick(1993) conducted a study
using himself and three members of his
family. They practiced foreign language
word translations for a set number of times
but for varying intervals of time (14-56 days).
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What were the findings? The longer the space
between practice sessions, the better the retention of
the words up to 5 years later.
Practical application: spacing learning out is more
beneficial. Reassessing retention is beneficial. Testing
effect: testing can improve learning , not just assess it,
Henry Roediger and Jeffrey Karpicke (2006).
Karpicke and Roediger(2008), gave study
participants 40 Swahili words to learn. Students
recalled the 40 words better if tested repeatedly than
if they spent the same time restudying the words.
Spaced study and self-assessment beat cramming.
Serial position effect: our tendency to recall
best the first and last items in a list.
 Serial position effect shows the benefits of
rehearsal. We often remember things at the
end of a list (recency effect), if we are
asked to recall them soon after hearing
them. This is probably because they are still
in our working memory. But after a delay,
we can best remember the things at the
beginning of the list(primacy effect).
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We process information by either
encoding its meaning, encoding its
image or mentally organizing it.
 When processing verbal information, we
usually encode by its meaning. We
associate it with what we already know
or imagine. Context and experience
become very important in this scenario.
 What type of encoding produces the
best memory of verbal information?
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Visual encoding of information is the
encoding of picture images.
 Acoustic encoding is the encoding of
the sound, especially the sound of words.
 Semantic encoding is the encoding of
meaning, including the meaning of
words.
 Each of these methods has its own brain
system and each one can help you to
remember verbal information.
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In 1975, Fergus Craik and Endel Tulving
compared visual, acoustic and semantic
encoding. They flashed a word at
people and then asked a question that
required the participants to process the
word at one of three levels.
 1 visually (appearance of the letters)
 2 acoustically (the sound of the word)
 3 semantically (the meaning of the
word)
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1. Is the word in capital letters? CHAIR
 2. Does the word rhyme with train? brain
 3. Would the word fit in the following
sentence?
 The man put the ____ on the table. Plate
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Which type of processing would best
prepare you to recognize the word at a
later time?
In their experiment, the deeper processing
required for #3 led to better memory of the
word than did the more shallow processing
of #2 and especially #1.
 Semantic processing aids memory if we
have enough context to process the
meaning of the content.
 John Bransford and Marcia Johnson (1972)
conducted an experiment on the
importance of context to semantic
encoding.
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Try to remember the following passage.
› The procedure is really quite simple. First you
arrange things into different groups. Of
course, one pile may be sufficient
depending on how much there is to
do…After the procedure is completed one
arranges the materials into different groups
again. Then they can be put into their
appropriate places. Eventually they will be
used once more and the whole cycle will
then have to be repeated. However, that is
part of life.
In the study, when participants heard the
passage without meaningful context,
most could remember very little of it.
 When told that the passage described
washing clothes, they remembered
much more of it.
 The conclusion: processing a word
through semantic encoding produces
better recognition later than does
shallow processing (visual or acoustic).
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Ebbinghaus concluded from his own
experimentation that learning
meaningful information required onetenth of the effort that learning nonsense
information did.
 Point to remember: The amount
remembered depends both on the time
spent learning and on your making it
meaningful.
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Visual encoding begins at our earliest memories
primarily because we lack words and must rely on
images.
Visual encoding does help with the memory of
concrete nouns, especially when incorporated with
semantic encoding.
Our memories of experiences is often inaccurate
because of the vividness of visual imagery. This can
lead us to remember the best or worst moment of an
experience, instead of the overall event. It is a
phenomenon called rosy retrospection. We have a
tendency to recollect the high points of an
experience.
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Mnemonic devices have visual imagery at the center. The
ancient Greeks used such devices to help them memorize long
passages and speeches.
Common mnemonic devices are the first letter approach,
substitution technique, the peg word system and the method of
loci.
First letter approach: Roy G. Biv
Substitution technique: replace numbers with letters, as in when
business phone numbers spell a word
The peg word system requires memorizing a jingle and then using
it as a memory tool
Method of loci: memory palace, uses a memory of a particular
place which is composed of a number of discrete loci. The loci
are then as memory locations for objects to be remembered.
The objects are linked to the loci with a visual image. To
remember them all one must do is mentally stroll through the
loci.
Mnemonic devices can help organize
material for later retrieval.
 Chunking is also a helpful method to
improve memory. Information is easier to
remember when organized into
meaningful chunks.
 Nickels Seven Any In Stitch Don’t
 Saves Ago A Score Time And
 Nine Wooden Four Years Take
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Don’t take any wooden nickels
Four score and seven years ago
A stitch in time saves nine
Chunking can also be used to learn and recall
new information.
Examples: Roy G. Biv, HOMES or My very
educated mother just served us nachos.
People also chunk information into hierarchies,
as they become more knowledgeable about
the topic. The hierarchies are organized
around broad topics, subprinciples and
specific content.
Hierarchies help us to retrieve
information efficiently.
 Gordon Bower ,et al (1969)
demonstrated this in a study. They
presented words either randomly or
grouped into categories. When the
words were organized into groups the
recall was two to three times better.
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Sensory memory: there are two types of
sensory memory.
 Iconic memory: a momentary sensory
memory of visual stimuli; a photographic
or picture image memory lasting no
more than a few tenths of a second
 Echoic memory: a momentary sensory
memory of auditory stimuli; if attention is
elsewhere, sounds and words can still be
recalled within 3 or 4 seconds
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In a 1960 study, George Sperling showed participants
three rows of three letters for about one-twentieth of
a second. After the letters disappeared the
participants could only remember about half of
them.
Sperling believed that the letters could only be
remembered momentarily but that all of them were
remembered. The problem was timing. He devised a
method to account for that. After the numbers
disappeared, he would sound a tone. High for the
top row, medium for the middle tone and low for the
bottom row. By sounding different tones he could
prove that the numbers were all remembered. All
nine letters were momentarily available for recall.
Sperling’s experiment revealed that we
do have a quick and fleeting
photographic memory(iconic memory)
 For a brief space of time (tenths of a
second), our eyes register an exact visual
representation of the scene and we can
recall it with amazing detail. But if the
recall was delayed by more than half a
second the recall was again cut in half.
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Echoic memory holds auditory stimuli for
three to four seconds.
 This explains why the following occurs: You
are sitting in class, not paying attention.
The teacher realizing that you are not
paying attention calls on you. What did I
just say? When you are able to answer the
teacher, this is your echoic memory. If the
teacher waits about 10 seconds before
calling on you, you may not know what she
said.
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Without rehearsal most information leaves our
brains within a short period of time. To retain
information our working memory must encode
or rehearse the information.
Peterson and Peterson tested the theory of
how quickly will a short term memory
disappear in 1959. Participants were asked to
remember a three consonant combination. To
prevent rehearsal, they were then asked to
count backwards from 100 by threes. After 3
seconds, the participants recall was only about
50%; after 12 seconds, they seldom
remembered them at all.
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Short term recall is:
Slightly better for random digits than
random letters
Slightly better for what we hear than see
Covers about as many words as you can
speak in 2 seconds
More spoken words that signed words
Basic Principle: At any given moment, we
can consciously process only a very limited
amount of information.
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How do we store memories in the brain?
For many years, researchers believed that your whole
life was in your brain. They believed this because of
flashbacks triggered from brain stimulation during
surgical procedures.
Loftus and Loftus analyzed this in 1980, and
discovered that the flashbacks seemed to have
been invented not relived.
In 1950, Karl Lashley, demonstrated that memories do
not live in one discrete location but are located in a
variety of places throughout the brain. He trained rats
to complete a maze, then he excised different parts
of their cortex. He then retested them. Regardless of
which small piece he had removed, the rats retained
some memory of how to complete the maze.
We know that experience changes the
brain’s neural pathways. Increased
activity causes a pathway to strengthen
or form new neural connections.
 We know that during learning, certain
neurons will send out larger amounts of
certain neurotransmitters. These synapses
become more efficient at transmitting
messages.
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Increased synaptic efficiency leads to more
efficient neural circuits. In experiments, rapidly
stimulating memory circuit connections has
been shown to increase the sensitivity of the
memory circuit connections for hours, days,
sometimes even for weeks.
The sending neuron now needs less prompting
to release its neurotransmitters and the
receiving neuron’s receptor sites may increase.
This strengthening is called LTP or long term
potentiation. LTP provides a basis for learning
and remembering associations.
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How do we know that LTP is a physical basis for
memory?
Drugs that block LTP interfere with learning
(Lynch & Staubli, 1991)
Mutant mice engineered to lack an enzyme
needed for LTP can’t learn their way out of a
maze (Silva, et al, 1992)
Rats given a drug that enhances LTP will learn
a maze with half the mistakes usually made
(Service, 1994)
Injecting rats with a chemical that blocks the
preservation of LTP erases recent learning
(Pastalkova, et al, 2006)
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One possibility is to create drugs that boost the
production of CREB, a protein that can switch genes
on and off. Here’s how it might work:
1) genes code the production of protein molecules
2) with repeated neural firing, genes produce
synapse strengthening proteins
3) this enables LTP
4) CREB might lead to increased production of
proteins that reshape and strengthen synapses and
help to consolidate ST memory into LT memory
Studies with sea slugs, mice and fruit flies have shown
that increased CREB production can lead to
enhanced memory.
A different approach is also developing
drugs that boost glutamate. Glutamate
is a neurotransmitter that enhances
synaptic communication (LTP). The
problem with glutamate is the potential
for side effects (migraines, seizures).
 With all drug therapies, comes the
potential for creating minds so cluttered
with the trivial that we can no longer
think.
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We know that adequate sleep enhances
memory.
 We also know that ECT, after LTP has
occurred does not disrupt memory.
However, new memories (no LTP) are
wiped clean by ECT(electroconvulsive
therapy).
 Head injuries can do the same.
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There are currently companies working
on pharmaceuticals to boost memory.
They have a huge target population.
Those with Alzheimer’s disease,
dementia, mild cognitive disorders
(which can become Alzheimer’s) and
those that would just like to turn back
time.
In writing, discuss the implications of drug
based memory enhancement. Be sure to
address positives, negatives and ethical
issues.
 Due next class.
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When we are excited or stressed our bodies
produce stress hormones. These hormones
make more glucose available to fuel brain
activity, indicating to the brain that
something important is happening. The
amygdala will also boost activity and
available proteins in the memory forming
areas of the brain.
 This an sear certain events in the brain while
disrupting the memory for neutral events.
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Stronger emotions seem to create stronger
memories. Memories of traumatic events
seem to intrude over and over.
 This make adaptive sense. These strong
memories serve as a reminder to protect us
and keep us alert to danger.
 Weaker emotions seem to create weaker
memories. Cahill in 1994 found that people
given a drug that blocked stress hormones
had more difficulty remembering details of
a upsetting story.
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Flashbulb memories are clear memories of
an emotionally significant event or moment
 Flashbulb memories can be explained by
the emotion-triggered hormonal changes
that occur during the event.
 Flashbulb memories are more authentic
when we experience the event as opposed
to hearing about it. Rehearsing, reliving and
discussing the memory are more likely to
lead to errors seeping into the memories.
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Implicit memory
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Explicit memory
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Implicit memory: non-declarative memory
Learning how to do something
Implicit is usually impossible to explain and
involves skills we learn
Without conscious recall
Processed by brain areas (not hippocampus)
like the cerebellum
Skills-motor and cognitive
Classical conditioning
Explicit memory: declarative memory
Explicit memories are usually easy to explain
and involves episodes we experience and
facts we learn
With conscious recall
Processed in the hippocampus
Facts-general knowledge
Personally experienced events
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H.M. : in 1953 had his
hippocampus removed
due to seizure disorder
Old memories intact
No new memories formed
Could develop skills at
performance of tasks but
did not remember tasks
Several researchers
(Brenda Miller, Suzanne
Corkin)
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Jimmy : suffered a brain
injury in 1945
All new memories stopped
at that point
Studied by Oliver Sacks
In the 1970’s believed that
Truman was president, no
way we landed on the
moon
Confused and distressed
by mirror image of self
Like others can find a room
but not tell you where it is,
gets faster a skill activities
but does not remember
them
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Brain scans have shown that when we
are recalling words (Squire, 1992) and
autopsies of people with amnesia have
shown that the hippocampus (a
temporal lobe neural center, part of the
limbic system) is responsible for laying
down our new explicit memories of
names, events and images.
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Kamil & Cheng, 2001 and Sherry &
Vaccarino, 1989 studied the ability of
chickadees to remember the location of
their food caches. Chickadees and
other birds store food in hundreds of
places and then return to those places in
the winter for food. If their hippocampus
has been removed they cannot locate
the food caches.
The hippocampus is lateralized. (having
one on each side of the brain)
 Damage to one or the other seems to
produce differing results.
 For example; with left hippocampus
damage, people have trouble with
verbal information but have no difficulty
with visual design or location information
 With right hippocampus damage the
problem is reversed.
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New research is working with the subregions
of the hippocampus.
 Zeineh et al(2003) one part is active as you
learn faces with names
 Maguire et al (2003)a different part is active
when memory whizzes engage in spatial
mnemonics
 Maguire et al (2003) the rear area of the
hippocampus grows in cab drivers who
have been navigating London’s streets
based on length of time
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The hippocampus is active during slow wave sleep, while
memories are being processed.
 The greater the hippocampus activity while sleeping (after
a training exercise) the greater the next days recall. These
memories are not permanently stored in the
hippocampus, rather it acts as a loading dock where the
brain registers and temporarily holds the days events,
locations, smells and names. Then the memories shift to
other locations for storage.
 Tse, et al (2007) removed the hippocampus of rats 3 hours
after they had learned the location of a tasty treat. The
process was interrupted and the rats could not remember.
No long term memory had been formed. The same
procedure performed after 48 hours did not impact the
formation of a long term memory.
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During sleep activity levels correlate
between the hippocampus and the
brain cortex. Researchers believe that
this “dialogue” is the process of
memories being consolidated and
transferred into long term storage.
 Once stored these memories activate
various parts of the frontal and temporal
lobes.
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The cerebellum plays a key role in
forming and storing your implicit
memories. Associations learned through
classical conditioning are not made by
people with a damaged cerebellum.
 The cerebellum is likely involved in the
learning of new skills.
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Our dual system may explain infantile amnesia.
The implicit memory handles the reactions and
skills that you learn as a child and carry
throughout your life. But you generally cannot
anything (explicit) about your first three years.
Although you can remember a few things as a
young child, most adults can no longer recall.
This is partly because of the language issue,
adults store and retrieve memories using the
spoken word and non-speaking children have
not yet learned these words and partly
because the hippocampus is one of the last
parts of the brain to mature.