Download Chapter 1 - Learning and Memory

Chapter 3
Episodic and
Semantic Memory:
Memory for Facts
and Events
3.1
Behavioral
Processes
3.1 Behavioral Processes
•
Episodic (Event) Memories and Semantic
(Fact) Memories
•
How Humans Acquire and Use Episodic and
Semantic Memories
•
When Memory Fails
• Learning and Memory in Everyday Life—
Total Recall! The Truth about Extraordinary
Memorizers
•
Models of Semantic Memory
3
Episodic (Event) Memories and
Semantic (Fact) Memories
•
Who sailed across the ocean blue in 1492?
•
Christopher Columbus, of course.
•
How many people remember where they
were and what they were doing when they
first heard about Columbus?
4
Episodic and
Semantic Memories
•
Episodic memory—for a specific
autobiographical event within a spatial and
temporal context
Most students do not remember where and when
they first heard about Columbus.
•
Semantic memory—for facts or general
knowledge of the world
But, most students know about Columbus.
5
Comparing and Contrasting
Episodic and Semantic Memories
6
Episodic and
Semantic Memories
•
Declarative or explicit memory—general
terms for episodic and/or semantic memory
Memories are consciously accessible.
•
Nondeclarative or implicit memory—other
types of memory (includes motor skill
memories; e.g., how to tie a bow)
Memories are not always consciously accessible or
easy to verbalize.
7
1. Easy to
Communicate
2. Learned
in a single
experience
Episodic Memory:
Graduation
Semantic Memory:
George Washington
“Tell me where your
graduation took place.”
“Tell me who was the
first US President.”
School auditorium
“How many times did you
have to attend your
graduation before you
remembered the event?”
Once
“Do you remember
your graduation?”
3. Consciously
accessible
Yes!
Washington
“How many times do I
have to tell you a fact
before you know the
answer?”
Once, maybe
“Do you know who the
first US President was?”
Yes!
Non-Declarative
Memory: Shoelaces
“Tell me how you
tie a shoelace.”
“How many times did
you have to tie your
shoelace before you
‘learned how’?”
Many times!
“Do you know which
hand you use to start
tying your shoe?”
8
Which Comes First, Episodic or
Semantic Memory?
•
Episodic may develop from semantic.
•
Alternately, we forget the original episodic
context…
When we first heard about Columbus.
•
…because we rehearse semantic
information in different contexts over time.
We study Columbus in primary grades, in scouts,
at local museums, etc.
9
Can Nonhumans Have
Episodic Memory?
•
Many nonhuman animals have knowledge
of their world.
e.g., locations of food, danger
•
Little evidence that nonhuman animals
demonstrate self-awareness or sense of
time.
•
Nonhuman episodic memory may be very
different from human episodic memory.
10
Episodic Memory in Gorillas
•
Gorilla learned to use cards with abstract
drawings to represent certain fruits and
humans (semantic learning).
•
Used cards to identify fruit he had eaten the
day before, as well as who gave it to him
(episodic learning).
11
Episodic Memory in Scrub Jays
•
Scrub jays bury worms and nuts in sandfilled ice-cube tray compartments.
When allowed to recover food 4 hours
later, chose worms
(favorite food).
After 124 hours,
tended to choose
the still edible nuts.
Dr. Nicola S. Clayton, University of Cambridge
12
How Humans Acquire and Use
Episodic and Semantic Memories
•
Memory is better for information that relates
to prior knowledge (memory in context).
In study, participants remembered twice as many
story details if they saw a contextual sketch
before hearing the story.
•
*Application* Skim a textbook chapter for
key points before you read its details.
13
Effects of
Organization on Memory
If the balloons popped, the sound wouldn’t be able to carry,
since everything would be too far away from the correct floor.
A closed window would also prevent the sound from carrying,
since most buildings tend to be well-insulated. Since the whole
operation depends on electricity, a break in the middle of the wire
would cause problems. Of course, the fellow could shout, but
the human voice is not loud enough to carry that far. An additional
problem is that a string could break on the instrument. Then there
could be no accompaniment to the message. It is clear that the
best situation would involve less distance. Then there would be
fewer potential problems. With face-to-face contact, the least
number of things could go wrong.
14
Effects of
Organization
on Memory
(a) Data from and (b) adapted from Bransford and Johnson, 1972.
15
Effects of
Organization on Memory
If the balloons popped, the sound wouldn’t be able to carry,
since everything would be too far away from the correct floor.
A closed window would also prevent the sound from carrying,
since most buildings tend to be well-insulated. Since the whole
operation depends on electricity, a break in the middle of the wire
would cause problems. Of course, the fellow could shout, but
the human voice is not loud enough to carry that far. An additional
problem is that a string could break on the instrument. Then there
could be no accompaniment to the message. It is clear that the
best situation would involve less distance. Then there would be
fewer potential problems. With face-to-face contact, the least
number of things could go wrong.
16
Effects of
Organization on Memory
Aoccdrnig to rscheearch at Cmabrigde
Uinervtisy, it deosn't mttaer in waht
oredr the ltteers in a wrod are, the olny
iprmoetnt tihng is taht the frist and lsat
ltteer be at the rghit pclae. The rset can
be a toatl mses and you can sitll raed it
wouthit a porbelm. Tihs is bcuseae the
huamn mnid deos not raed ervey lteter
by istlef, but the wrod as a wlohe.
17
Deeper Processing at Encoding
Improves Recognition Later
•
Depth of processing
The more meaningfully you analyze information at
encoding, the stronger the retrieval.
FORNIX
18
Deeper Processing at Encoding
•
In study, students studied some adjectives
by generating related images.
Deep processing
•
Other adjectives were studied through
backwards pronunciation.
Shallow processing
•
(Dirty=dumpster)
(happy= Yip-Pah)
Students recognized more “image” words
than “pronounce” words.
19
Deeper Processing at Encoding
•
Student fMRIs showed more brain activity
during “image” encoding than during
“pronounce” encoding.
(a) Data from and (b) adapted from Davachi et al., 2003.
20
The Forgetting Curve
and Consolidation
•
Most forgetting occurs in the first few hours
or days (Ebbinghaus).
•
Squire tested adult memory for one season
TV shows from 1 to 15 years prior.
Remembered more than 75% of the previous
year’s shows.
Recollection dropped from 2 to 9 years.
Remembered almost as many shows from 15
years ago as from 10 years ago.
21
The Forgetting Curve
and Consolidation
•
Declarative memories may have a
consolidation period—length of time
during which new memories may be lost.
•
In study, rats had severe memory loss from
electroconvulsive
shock (ECT) 20 seconds
after training.
Shock an hour after
training had little effect.
Will McIntyre/Photo Researchers, Inc.
22
The Forgetting Curve
and Consolidation
•
Squire and colleagues also test depressed
patients’ memory for one-season TV shows
from 2 to 15 years prior.
•
Test conducted right before and a week
after ECT.
Temporary retrograde amnesia for the TV shows
from 2 to 4 years ago.
23
Forgetting in Humans
(a) Adapted from Squire, 1989; (b) adapted from Squire et al., 1975.
24
Transfer-Appropriate Processing
•
“Tip-of-the-tongue” phenomenon—when
memory is temporarily inaccessible.
•
Transfer-appropriate processing—retrieval
more likely if cues at encoding and recall are
similar.
Context may be a factor (e.g., words to words or
images to images).
Depth of processing at encoding helps when
retrieval requires deep processing (e.g., requires
knowledge of semantic meaning).
25
Transfer-Appropriate
Processing: Research
•
In study, divers studied some words
underwater and others on the beach.
Words learned underwater were best recalled
underwater.
Words learned on the beach were best recalled
on the beach
When learning and recall environments were
radically different, recall dropped about 40%.
26
Transfer-Appropriate
Processing: Research
•
But, in another study, college students took
final exams in:
The same room where the course was taught.
A novel classroom.
•
Students’ exam performance was not
affected by testing in a new classroom.
27
*Demonstration*
•
Write down as many names of the seven
dwarfs as you can remember.
•
Don’t consult with your classmates; just use
your own memory.
28
Who knows Snow White?
Grouchy
Gabby
Fearful
Sleepy
Smiley
Grumpy
Hopeful
Dumpy
Wishful
Puffy
Jolly
Sneezy
Lazy
Pop
Bashful
Silly
Wheezy
Shy
Cheerful
Droopy
Teach
Hapless
Happy
Goofy
Sniffy
Doc
Dreamy
Nifty
Dopey
Drippy
Jumpy
Golly
29
The Seven Dwarfs
Grouchy
Gabby
Fearful
Sleepy
Smiley
Grumpy
Hopeful
Dumpy
Wishful
Puffy
Jolly
Sneezy
Lazy
Pop
Bashful
Silly
Wheezy
Shy
Cheerful
Droopy
Teach
Hapless
Happy
Goofy
Sniffy
Doc
Dreamy
Nifty
Dopey
Drippy
Jumpy
Golly
30
More Cues Mean Better Recall
•
Free Recall—generate response from
memory.
•
Cued Recall—a prompt given to facilitate
response generation.
•
Recognition—identify target from
distracter items.
*For those who did not recall all 7 dwarf
names, did recognition help?
31
Learning and Memory in Everyday Life—
Total Recall! The Truth about
Extraordinary Memorizers
•
There is no scientific evidence that
photographic memories exist.
•
Eidetic imagery
is the ability to
store visual
information.
Usually fades
after a few
seconds.
Rare Books Division, The New York Public Library, Astor, Lenox, and Tilden Foundations
32
Learning and Memory in Everyday Life—
Total Recall! The Truth about
Extraordinary Memorizers
•
Expert memorizers use elaborate
mnemonics.
e.g., peg-word method, method of loci
•
No evidence that mnemonics offer an
advantage in everyday life.
33
When Memory Fails:
Interference
•
Interference—when two memories are
similar, the strength of either or both may
be reduced. (car parking, etc?)
Proactive interference—old information disrupts
new learning.
Retroactive interference—new information
disrupts old learning.
34
Proactive Versus Retroactive
Interference
•
A simple mnemonic for remembering the
difference between proactive and
retroactive interference:
PRoactive means PReviously-acquired
information interferes with newly-acquired
memories.
REtroactive means REcently-acquired
information is interfering with previouslyacquired memories.
35
Two Kinds of Interference
36
When Memory Fails:
Source Amnesia
•
Amnesia—memory loss
•
Source amnesia—confusion over the
source of a memory (fact or event)
•
Includes cryptomnesia:
Mistakenly thinking an idea is original.
Can lead to unintentional plagiarism.
37
Cryptomnesia Research
•
Marsh and Bower Experiment:
Using a letter grid
participants form words;
play against computer.
Later, must write down
all words they (not the
computer) generated.
Remember many of own
words, but about 10% of
the words were the
computer’s.
S T
C A
G L
A N
E
O
I
L
Y
S
N
D
Example Words:
Act
Nose
Again
Note
Call
Oil
Gate
Stain
Lion
Yes
38
When Memory Fails:
False Memory
•
False memory—memory for events that
never occurred.
•
In studies, Loftus and others created false
memories by using plausible childhood
events, family support, doctored photos.
Prompt participants to imagine missing details.
Participants confuse imagined details with reality.
39
Figure 3.7 Creating false memories in the laboratory
Gluck, Mercado and Myers: Learning and Memory, First Edition
Copyright © 2008 by Worth Publishers
40
False Memory for Words
•
Participants saw and heard words, then
wrote down the words they could recall in
any order (free recall).
•
Some recalled a word associated with all
presented words but NOT seen or heard
(i.e., a false memory).
Identified during a recognition test. Did you recall
the word ________?
41
Data from Cabeza et al., 2001.
False Memory for Studied Words
42
Models of Semantic Memory
•
Metaphors for memory organization
•
Conceptual models of mind, not physiological
models of brain
•
Hierarchical semantic network—concepts
represented as “nodes”; arranged
hierarchically according to class.
Relationships between objects/concepts are
encoded as connections or links.
New learning represented by additional nodes and
features.
43
Hierarchical Semantic Network
•
In this organization, more specific nodes
and features are found.
New nodes added toward bottom of network.
Generalization occurs from above.
44
*Demonstration*
•
What general concept (the superordinate
category) might you organize hierarchically
in small group work?
•
Exchange examples with another group.
45
Hierarchical Semantic Network
46
3.1 Interim Summary
•
Episodic memory = autobiographical
events we “remember.”
•
Semantic memory = general fact
information we “know.”
•
Both generally accessible to conscious
recall, can be communicated flexibly.
47
3.1 Interim Summary
•
Key differences:
Episodic memory—always acquired in single
exposure; always includes spatial/temporal context.
Semantic memory—strengthened by repeated
exposure; need not include spatial/temporal
information.
•
Some believe only adult humans capable of
true episodic memory.
Have sense of self; can relive past experiences.
48
3.1 Interim Summary
•
Factors affecting successful episodic and
semantic memory encoding/retrieval:
Can information be related to preexisting
knowledge?
How is information processed (Deep or shallow)?
Do encoding and recall conditions match?
How many cues are available to prompt recall?
•
Most simple forgetting occurs early after
the event (e.g., Ribot gradient).
49
3.1 Interim Summary
•
Memories also lost or distorted through:
Interference
Source amnesia
Cryptomnesia
False memory
•
Hierarchical semantic networks = model for
information encoding.
Links (relationships) between nodes (concepts or
objects)
50
3.2
Brain
Substrates
3.2 Brain Substrates
•
The Cerebral Cortex and Semantic Memory
•
The Medial Temporal Lobes and Memory Storage
•
Hippocampal-Cortical Interaction in Memory
Consolidation
•
The Role of the Frontal Cortex in Memory Storage
and Retrieval
•
Unsolved Mysteries—Are There Different Brain
Substrates for Episodic and Semantic Memory?
•
Subcortical Structures Involved in Episodic and
Semantic Memory
52
The Cerebral Cortex and
Semantic Memory
•
Sensory cortices help process sensory
information, including:
Auditory cortex in superior temporal lobe.
Visual cortex in the occipital lobe.
Somatosensory cortex in parietal lobe.
•
Association cortex links information within
and across sense modalities.
53
Semantic
Memory and
the Cerebral
Cortex
54
Cerebral Damage and
Semantic Memory
•
Agnosia—difficulty processing sensory
information
May result from cortical damage.
Associative visual agnosia—patients cannot
recognize or name objects (though they can may
have ability to identify by feel, or draw).
•
Agnosia can be specific to category (visual,
auditory, tactile).
55
Category-Specific Agnosia
•
Functional attributes may be intact…
What do we do with a bicycle?
•
…with physical attribute impairment
How large is an adult bicycle?
•
Farah and McClelland (1991)
Semantic networks may be organized by
categories of attributes.
Functional properties
Visual properties (including size)
56
The Medial Temporal Lobes
and Memory Storage
•
Medial temporal lobes (MTL) includes:
Hippocampus
Amygdala
entorhinal cortex
perirhinal, cortex
parahippocampal cortex
•
Bilateral damage results in anterograde
amnesia (cannot form new memories).
H.M. case study
57
MTL in Humans
58
Normal Versus Anterograde Amnesia
(A) “Normal” Memory
Memories
Recalled
Birth
Childhood
Adulthood
Today
Years
(B) Anterograde Amnesia (H.M.)
Memories
Recalled
Birth
Childhood
Adulthood
Years
Time of
Trauma
Today
59
The Hippocampal Region and
Memory in Nonhuman Animals
•
Monkeys have similar MTL to humans.
•
Rats and rabbits have same structures,
different organization and structure sizes.
•
Birds and reptiles have a single structure.
•
Nonhuman animals with hippocampal
region lesions experience anterograde
amnesia.
60
Hippocampal Region in Animals
61
The Hippocampal Region and
Memory in Nonhuman Animals
•
In studies:
Healthy rats learned to
find food at the end of all
8 arms of a radial maze
with few errors.
Rats with hippocampal
lesions made many errors,
losing track of which
rewards they had already eaten.
Lesioned scrub jays searched
for their buried food caches randomly.
62
•
In studies, fMRI shows more active MTL
during encoding of words
and images that participants
successfully recalled.
Successful word recall
associated with left MTL and
frontal lobe activation at
encoding.
Successful picture recall
associated with bilateral MTL
activation.
Science Magazine/Courtesy of Anthony D. Wagner
Hippocampal Function in the
Healthy Brain
63
Hippocampal Function in the
Healthy Brain
•
Hippocampus might integrate objects (e.g.,
words) into spatial and temporal context.
•
In the “false memory for an unseen word”
study, fMRI during recognition showed high
activity for seen words and the false
memory word.
A small area of MTL did not respond to the false
memory word.
64
Hippocampal-Cortical Interaction
in Memory Consolidation
•
Those with anterograde amnesia may also
experience retrograde amnesia (inability
to retrieve memories closest to injury).
•
E.P. case study:
Experienced bilateral MTL damage from
encephalitis.
Severe amnesia for a decade of his adulthood,
but strong childhood memories.
65
Ribot Gradient: Evidence for
Consolidation Period
Retrograde
Amnesia
Anterograde
Amnesia
Memories
Recalled
Birth
Childhood
Adulthood
INJURY
Today
Years
66
Might the Memory Consolidation
Period Extend to Decades?
•
Standard consolidation theory—episodic
memory retrieval becomes less dependent
on MTL as cortical areas of the memory
components (e.g., sight, sound) integrate.
•
Multiple trace theory—episodic memories
depend more on cortical neurons and less
on hippocampus over time.
67
Might the Memory Consolidation
Period Extend to Decades?
•
Patients with amnesia may rehearse what
was once an episodic memory to the point
that it becomes semantic.
Then, they “know about” an event.
•
Healthy people can maintain episodic
memories of truly “remembering” an event.
68
The Role of Frontal Cortex in
Memory Storage and Retrieval
•
Frontal cortices may be important in
declarative memory development.
Facilitates attention, judgment, cognitive control.
May inhibit hippocampal encoding during directed
forgetting.
Damage increases source amnesia (confusing
reality and fantasy).
69
Directed Forgetting
(a) Data from and (b) adapted from Anderson et al., 2004.
70
Unsolved Mysteries—
Are There Different Brain Substrates for
Episodic and Semantic Memory?
•
Semantic learning depends on medial
temporal areas (including entorhinal,
perirhinal cortices).
Hippocampus may be needed for extra ability to
record autobiographical context of episodic
memories.
71
Unsolved Mysteries—
Are There Different Brain Substrates for
Episodic and Semantic Memory?
•
Other researchers argue that semantic
memories depend on episodic memories.
Many persons with amnesia have difficulty
developing both episodic and semantic
memories.
Especially when hippocampal damage extends
into the cortex.
72
Subcortical Structures Involved in
Episodic and Semantic Memory
•
Diencephalon—structures include
mammillary bodies and mediodorsal nucleus
of thalamus
•
Basal forebrain—structures at base of
forebrain
Fornix—arch-like fiber bundle, connects
diencephalon and basal forebrain to hippocampus.
•
Damage to diencephalon, basal forebrain or
fornix causes anterograde amnesia.
73
Diencephalon and
Basal Forebrain
74
The Diencephalon May Help
Guide Consolidation
•
Korsakoff’s disease:
Thiamine (vitamin B1) deficiency
Sometimes accompanies chronic alcohol abuse.
Patients act like they have MTL damage, but
damage is to diencephalon and other structures.
•
Diencephalon might mediate frontal cortex
and hippocampus during memory formation;
damage could cause anterograde and
retrograde amnesia.
75
Basal Forebrain May Help Determine
What the Hippocampus Stores
•
Basal forebrain is a MTL regulator.
•
Certain strokes can lead to basal forebrain
damage, resulting in anterograde and
retrograde amnesia.
e.g. anterior communicating artery (ACoA)
aneurysm
•
With frontal cortex damage and Korsakoff’s
disease, survivors may confabulate (confuse
free associations with reality).
76
3.2 Interim Summary
•
Cerebral cortex stores semantic memories.
•
Different kinds of cortical damage may
present as disruptions in semantic abilities.
Difficulties remembering the purpose or meaning
of words, objects, faces.
•
Many cortical areas are prey to
false-memory effect.
Activity is similar for false and familiar items
Region in MTL may signal if memory is true/false.
77
3.2 Interim Summary
•
Hippocampal region is active during encoding
of material that will be remembered later.
•
Damage to hippocampal region typically
presents as:
Severe anterograde amnesia
Failure to acquire new event memories.
Retrograde amnesia
Loss of memory for events that occurred before injury.
78
3.2 Interim Summary
•
Unclear if episodic memories can become
fully independent of hippocampus, or if
hippocampus always helps access to
memories stored in cerebral cortex.
•
Frontal cortex may help bind event memory
with spatial/temporal context.
Individuals with damage to frontal cortex are
prone to source amnesia.
79
3.2 Interim Summary
•
Diencephalon and basal forebrain:
Key roles in memory.
Poorly understood.
•
Damage to either area presents as
anterograde amnesia similar to MTL damage
memory loss.
80
3.3
Clinical
Perspectives
3.3 Clinical Perspectives
•
Transient Global Amnesia
•
Functional Amnesia
•
Infantile Amnesia
82
Transient Global Amnesia
•
Transient global amnesia—temporary
memory disruption, often due to brief
interruption of blood flow to the brain from:
Head injury
Low blood sugar
Heart attack or stroke
Tranquilizers
Alcohol “blackouts”
83
Transient Global Amnesia
•
Starts suddenly, lasts for hours.
•
Usually ends within a day or so.
•
Severe anterograde amnesia for encoding
new episodic memories.
•
Patchy retrograde amnesia.
84
S.G. and
Transient Global Amnesia
•
S. G. = case study of 38 year old man:
Experienced temporary blood flow reduction to
his brain during surgery.
Remembered his name; could not remember
occupation, date, length of hospital stay.
Agreed to memory testing.
85
S.G. and
Transient Global Amnesia
•
About 2.5 hours after onset, showed
profound anterograde amnesia.
Could recall few words from a story read to him.
Suffered retrograde amnesia for his job, address
history, other personal information, recent world
events.
•
Memory improved; 24 hours after onset,
back to normal.
The only apparent loss was a slight retrograde
amnesia for events right before his surgery.
86
S.G. and
Transient Global Amnesia
(a, b) Adapted from Kapur et al., 1998.
87
Functional Amnesia
•
Functional (or psychogenic) amnesia—
results from psychological (rather than
physical) cause.
e.g., dissociative fugue
•
Loss of personal identity due to severe
psychological trauma.
Can be faked for personal gain.
88
P.N. and Functional Amnesia
•
P.N. (or Lumberjack) = case study of a 21
year old man
Severe retrograde amnesia for episodic
memories; intact language skills and semantic
memory.
One week after onset, a movie funeral on TV
triggered his recovery.
89
P.N. and Functional Amnesia
•
Extreme grief from his grandfather’s death
may have precipitated fugue.
He encoded no events during the episode due to
temporary anterograde amnesia.
•
In another case, PET scan found:
Decreased glucose metabolism in MTL and
medial diencephalon (structures involved in
memory storage and retrieval).
90
Infantile Amnesia:
Three Potential Factors
•
Infantile amnesia—the universal
forgetting of episodic memories prior to
age 3 or 4.
•
Potential Factors:
1.
Hippocampus and frontal cortex may need
to develop to a certain level to encode and
retrieve episodic memories.
91
Infantile Amnesia:
Three Potential Factors
2.
Self-recognition may be an important step
in episodic memory development.
Children develop a sense of self between 16
and 24 months (when they recognize
themselves in a mirror and try to rub off a
smudge on their face).
Chimps and dolphins develop self-recognition,
but many fish species do not.
92
Infantile Amnesia:
Three Potential Factors
3.
Loftus and Kaufman (1992) suggest
preverbal infants cannot encode and store
episodic memories in a way that is
accessible to them as adults.
93
3.3 Interim Summary
•
Transient global amnesia may be temporary.
Possibly caused when MTL are unable to carry out
normal encoding role.
•
Functional amnesia may be temporary.
May be caused by psychological trauma, rather
than discernable brain injury.
94
3.3 Interim Summary
•
Infantile amnesia = general lack of episodic
memories from first few years of life.
Possibly due to:
Immature brain structures.
No cognitive sense of self.
Absence of language skills.
95