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memory
Our essence
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A huge problem
• Eye witness testimony
• Witnesses are not always
right, even if they are certain
• Picking the wrong “rapist”
• How could this happen?
Memory overview
• A complex concept
• Refers to both the process of
retaining information, and
the information retained
• Many types, uses, and tests
• What are we without it?
Three Processes
• Encoding – getting the info and then
transforming it into a form that the brain
can retain
• Storage – holding the info
• Retrieval – pulling it out
Three models
• Levels of processing – how long and how
intensely we work with a memory
determines how well we retain and retrieve
it
• Parallel distributed processing – we
remember things in many different forms
all at once, in parallel
Information
processing view
• Based on a computer model conception of
memory
• Proposes that information enters the
system, is processed and coded in various
ways and then stored
• Sets out three
components
Sensory store
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The first filter
A very brief capture of sensory information
Images involve iconic memory
We can attend to anything in our visual
field – lasts for ½ second
• But if we do not attend to something, it is
lost
Short-term memory
• Temporary storage of information you
have just experienced
• Lasts for about 20-30 seconds, unless
rehearsed
• Holds 7 (plus or minus 2) items, like a
crowded elevator holds passengers
• Can be effectively extended by
memorizing information in chunks –
meaningful units
Was Dori right?
• That adorable tang claimed to have a
problem with her short term memory.
• Did she?
• Could she hold 7 or so items in mind if she
continued rehearsing them?
Long-term memory
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Unlimited capacity
Lasts (usually) as long as you do
Weakened by interference
Also vulnerable to loss of retrieval cues
Usually located in the frontal lobes
Meaningful, distinctive material goes in
quickly
The working
memory theory
• Over time, the information processing
theory’s concept of short term memory
sprung more and more leaks
• How do long term memory and short term
memory work together?
• From these and many other concerns, the
concept of working memory began to
emerge
More “working”
• A system for processing or ‘working’ with
current information
• The thoughts, facts, ideas, and feelings in
our current sphere of attention, a mix of
current experience and retained memories
• Some of these new items might eventually
be stored in LTM, others might not
Three systems within working
memory
• Central executive – controls and
coordinates the
• Visuospatial sketchpad and the
• Phonological loop
The crucial focus
• “How does this information apply
to some experience in my own
life?”
• Make it your own and it will be
yours forever.
• Also known as elaborative
rehearsal
Long-term memory
storage
• To improve our memory we must improve
the way we store information
• Just repeating things, over and over again,
will not help us remember them
• We must process (work with) them
deeply, by focusing on meaning
Levels of
processing
• Our ease in retrieving a memory depends
on the number and types of links we make
with it
• The more links or connections we make
with the information, the better we will
remember it
• Use links that mean something to you
Memory systems
• Implicit Memory – memories which are
influenced by experiences, often without
awareness
• Easier to do than explain
• This memory system is often primed, or
prepared, by events on the fringe of our
attention
• The cocktail-party effect
Procedural
memories
• Memory of skills, procedures, habits, even
conditioned responses
• A subset of the implicit memory system
• There are plenty of things that we can
easily do, but have great difficulty
describing
• Very hard to “forget”
• Riding a bike, typing, tying a tie, etc.
Declarative memory
• Contrasts with implicit/procedural memory
• Consists of memories we can easily state
in words
• What we know verbally
• We can lose this type of memory and yet
retain implicit/procedural memories
More memory types
• Semantic – memory of general principles
• Quite resistant to decay
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Episodic – memory of specific events
Vulnerable to decay
Combination leads to source amnesia
“I heard about that, but I can’t remember
where.”
The importance of cues
• Retrieval cues – prompts or stimuli to aid
remembering
• The more the merrier
Encoding
specificity
• Associations formed while learning are the
most effective retrieval cues
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This classroom
This time of day
Same chair
Same people
State-dependent
memory
• Tendency to remember something better if
your body is in a similar condition when
you attempt to recall it, as it was when you
first learned it
• Mood – cognitive view of depression
• Drugs – if you studied under the influence,
you should …..
• Small effects
Assessing memory
• 1) Recall – Producing the desired
information without any cues or hints
Short answer/essay tests
Vulnerable to interference
• 2) Cued recall – Producing the
information with hints
Class picture for kindergarten names
• 3) Recognition – Picking out the desired
information from a number of alternatives
Multiple choice tests
• 4) Relearning – learning something for
the second time
Usually reveals “savings”, information
relearned much more quickly
The Serial Order Effect
• Primacy – we always remember the first
one
• Recency – and the last
Flashbulb memories
• Traumatic, highly emotional and
compelling memories seem to be
automatically encoded
• These memories are indelibly seared into
our memories
• We remember in astonishing detail
• Or do we?
• President Kennedy’s
assassination
• The Challenger explosion
• But research conducted
in the wake 9/11, show that
even these memories decay
Memory
reconstruction
• The problem is more than just forgetting
• We exaggerate, distort, and construct
what we “remember”
• Above all, memory is selective
• We typically remember best the gist of the
event
• The details can be much more elusive
Ebbinghaus & Interference
• Pioneered systematic study
• Memorized thousands of strings
of nonsense syllables
• Years later, novices trounced him in tests
• How?
Proactive interference – work with
similar material in the past makes learning
new material more difficult
Losing cues – losing memories
• We need cues to retrieve memories that
we have not processed for a while
• The memories are likely still there, but
finding them among billions of neurons
can be near impossible
The Biology of Memory
• We don’t gain memories without chemical
and structural changes in our neurons
• For short-term memory changes consist of
a temporary change in the ability to
release neurotransmitters
A Change in Structure
• For long-term memory the neuronal
changes are more basic and lasting
• A new long-term memory causes changes
in synaptic responsivity – long-term
potentiation
• Exchanges between these neurons are
chemically strengthened, and much more
likely to communicate in the future
More changes
• Not only are these neurons synapses
chemically strengthened,
• The neurons grow more dendrites and
forge more synapses
• This happens over time, a process called
consolidation
The strange case of
h. m.
• Suffered from severe, recurrent epileptic
seizures
• In desperation, his hippocampus was
removed
• Sure, his seizures decreased in severity
and frequency,
• But, forever after, he “was preoccupied,
with 1955”
Who is that?
• H. M. suffered almost complete
anterograde amnesia – no new LTM
• Every day, even 20 seconds, his memory
was wiped clean
• He couldn’t recognize his wife as she
aged, even himself
• He also demonstrated some retrograde
amnesia
Amazingly though, ..
• H. M. despite his appalling deficits, could
learn new skills, aspects of procedural
memory
• On the other hand, he did not know that he
had acquired the new skill, an aspect of
declarative memory
A preference for the mundane
• What we “remember” of events is often a
mixture of surviving memories and what
we expect must have happened
• We alter some memories so that, in
hindsight, they make sense
• But life is truly stranger than fiction
Emotional arousal
• We usually remember emotionally
arousing events but the accuracy of the
memory can suffer
• Arousal increases hormone levels which
excite the amygdala, which works with the
hippocampus to ensure storage
A Common Wild-Card – Source
Misattribution
• Often it is far easier to remember
something than it is to recall where we
heard it
• Since we experience or pick up so much
information, from sources which vary
greatly in credibility, this can lead to errors
• Others call it source amnesia
But where are they?
• Short-term – frontal lobes
• Long-term – hippocampus is essential, but
after processing, they go to the cerebral
cortex areas involved in their perception
• Any single memory is a complex
relationship of neurons scattered
throughout the cerebral cortex, linked
together at the start by the hippocampus
Mnemonic devices
• Any memory aid that relies on encoding
each piece of information in a specific way
• String items together in a story
• Method of loci – link
concepts or ideas with
places, or a path
• Clever, unusual images
are essential
More interference
• Retroactive interference – work with new
material makes old material harder to
remember
• Effect weakened by going to sleep right
after learning information
• No wonder ads shown during TV
programs with violent/sexual content are
routinely forgotten
timing
• Timing – spreading studying sessions
over time aids retention
• Even if you are able to devote a significant
amount of uninterrupted attention to the
material in one setting, you won’t
remember it as well
Repression
• Are some things so traumatic that we
involuntarily push them out consciousness
• Into the unconscious?
• Though Freud based many of his theories
on this phenomenon, it doesn’t work that
way.
• In fact, we often find it difficult to stop
thinking about horrible experiences