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Introduction to Long-Term Memory (LTM)
Psychology 355: Cognitive Psychology
Instructor: John Miyamoto
04/28/2016: Lecture 05-4
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Outline - Introduction to Long-Term Memory
• Reminder: Distinction between STM and LTM
• Different types of long-term memory
♦
Explicit versus implicit memory (declarative vs non-declarative memory)
♦
Episodic versus semantic memory
♦
Procedural memory
♦
Associative memory
• HM – a famous clinical case;
Illustrates many important aspects of memory
• Evidence for distinction between STM & LTM
• Evidence for distinction between episodic and semantic memory
• Evidence for distinction between explicit memory and
implicit memory.
Psych 355, Miyamoto, Spr '16
Picture Showing the STM/LTM Distinction
2
Figure 6.1: Example of the STM/LTM Distinction
LTM
Psych 355, Miyamoto, Spr '16
STM
Diagram of Modal Memory Model – Encoding, Retrieval & Consolidation
3
Control Processes
External
World
Sensory
Store
Short-Term
Store
Retrieval
Encoding
Long-Term
Store
Encoding, Retrieval & Consolidation
• Encoding – creating an LTM out of currently processed information.
• Retrieval – bringing information that is stored in LTM back
to STM
• Consolidation - creating a strong LTM by repeatedly retrieving and
manipulating an LTM; and by associating it with other memories.
Psych 355, Miyamoto, Spr '16
List of Functions That Are Included in LTM
4
LTM Includes .....
• Important information about the self and events in the world,
but also, ...
• Trivial information about what has happened in the recent past,
• “Semantic” knowledge, e.g., what is an apple, a pencil;
which is bigger, a mouse or a moose; etc.
• How to do things: Tie your shoes, drive a car, dial a phone number,
cook a meal, ....
• Learned associations that are not explicit, e.g., the atmosphere
of a dentist’s office makes you feel apprehensive.
Psych 355, Miyamoto, Spr '16
Diagram Showing the Major Components of the LTM System
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Different Types of Long-Term
Memory
Figure 6.12. Different Types of Long-Term Memory
• Declarative memory (explicit memory) – facts, knowledge, images
• Non-declarative memory (implicit memory) – non-conscious memory
that is expressed through change in behavior; it doesn’t necessarily
include conscious recollection.
Psych 355, Miyamoto, Spr '16
Intro to HM
6
HM – A Famous Clinical Case
• HM – initials of a man
See links to his biography on the Psych 355 website.
• Intractable epilepsy.
• August 25, 1953: Medial temporal lobes (left and right) were surgically
resectioned to treat his epilepsy. Removal of the hippocampus.
• Following surgery, HM had much milder symptoms of epilepsy, but ...
... he was found to have severe problems with memory.
Psych 355, Miyamoto, Spr '16
.
Where is the Hippocampus?
7
This slide is based on instructional material that was downloaded from the Pearson Publishers
website (http://vig.prenhall.com) for Smith & Kosslyn (2006; ISBN 9780131825086).
Where is the Hippocampus?
• HM underwent bilateral removal of much of the hippocampus,
amygdala and surrounding medial temporal cortices.
Amygdala
Hippocampus
Schematic head facing up.
Hippocampi are in red.
Psych 355, Miyamoto, Spr '16
HM’s Memory Problem
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HM’s Memory Post-Surgery
• HM could carry on a conversation, understand current situations.
• Severely impaired memory for any events occurring after brain injury.
(Severe anterograde amnesia)
• Some impaired memory for events occurring before injury.
(Some retrograde amnesia)
• Could learn new skills like sewing.
• Could learn some new semantic information, e.g., his brain
surgery was in 1953, but he learned that there was a president named
Kennedy who was assassinated.
Psych 355, Miyamoto, Spr '16
Diagram Showing Multiple Memory Systems
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Episodic & Semantic
Memory
HUMAN MEMORY
SHORT-TERM
MEMORY
Psych 355, Miyamoto, Spr '16
Memory Terminology – Including Types of Amnesia
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• Explicit memory (declarative memory)
♦
Episodic memory - memory for personal experiences
♦
Semantic memory - memory for facts
• Implicit memory (non-declarative memory)
♦
Priming – exposure to one stimulus can affect ability to perform
a cognitive task.
♦
Procedural memory - memory for how to do things,
e.g., how to type at a computer.
♦
Associative and non-associative learning
Discussed on Earlier Slide
Some Memory Terminology
• Amnesia
♦
Anterograde – amnesia for events occurring after brain injury.
♦
Retrograde - amnesia for events occurring before brain injury.
Psych 355, Miyamoto, Spr '16
Back to HM’s Memory Problems
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HM's Memory Problems
• Anterograde amnesia – very severe; he could not form new
permanent episodic memories.
• Retrograde amnesia – very severe for preceding 4 days; some
impairment up to 11 year preceding.
♦
Retrograde amnesia was temporally graded, i.e., less amnesia as you
go farther into the past.
----------------------------------------------------
• Declarative memory – severely impaired
♦
♦
Episodic memory – very severe
Semantic memory – severe but he could still learn some new general
facts.
• Procedural memory – relatively intact
♦
♦
HM learned to sew.
HM learned to draw mirror images.
Psych 355, Miyamoto, Spr '16
Diagram Showing that HM’s Memory Problem Pertains to Encoding
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HM's Explicit Memory Problem
Control Processes
External
World
Sensory
Store
Short-Term
Store
Retrieval
Encoding
Long-Term
Store
(Remember that this diagram is an over-simplification)
• HM's worst problem was encoding from STM (WM) to LTM. Impaired
transfer from STM to LTM.
• STM (WM) was still functioning because he could understand the
current situation.
• Note: This diagram omits the role of the hippocampus in
consolidation (probably HM had difficulty with consolidation as well as
encoding).
Psych 355, Miyamoto, Spr '16
STM/LTM Distinction and the Serial Position Curve
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How Do We Know that STM and LTM
Involve Different Brain Mechanisms?
Figure 6.3
Serial Position Curve
• Subject views list of 20
words, one word at a time.
Each word is presented for 2
seconds.
• After viewing the list, subject
attempts to recall as many
words as possible.
% Recalled
Evidence from the
Serial Position Curve:
Serial Position
• Curve shows the percentage of
times a word in each position
was recalled correctly.
Psych 355, Miyamoto, Spr '16
Interpretation of Standard Result for Serial Position Curve
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Interpretation of Standard Result for Serial Position Curve
Claims (to be substantiated in
Figure 6.3
Serial Position Curve
• Primacy effect is due to
transfer to LTM.
• Recency effect due to words
retained in STM.
• Standard result for serial
position curve is evidence for
STM/LTM distinction.
Psych 355, Miyamoto, Spr '16
% Recalled
subsequent slides)
Serial Position
Primacy
Effect
Recency
Effect
How to Prove that Primacy is Due to Transfer to LTM?
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How to Prove Primacy Effect Is Due to Transfer to LTM?
• Rundus (1971) presented words at the rate of
1 word per 5 seconds. 20 words in the list.
• Subjects were instructed to rehearse words aloud.
What Subject Sees
car
stone
What Subject Says
car, car, car, ...
car, stone, car, stone, car, ...
top
car, stone, top, car, stone, top, ...
......
...................
• This study has 2 dependent variables:
♦
Frequency of recall for words in each position
♦
Number of rehearsals for words in each position
Psych 355, Miyamoto, Spr '16
Results for Rundus Experiment
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Results for Rundus (1971) Study
Figure 6.4
Effect of Overt Rehearsal
Figure 6.4 to the right:
• Blue dotted line:
Number of times a word
in each position was
rehearsed.
% Recalled
(standard result)
Number of Rehearsals
• Red solid line:
Serial position curve
Serial Position
• Blue dotted line correlates perfectly with the serial position curve (red
dotted line) except for the recency effect. This supports claim that
primacy effect is due to transfer to LTM.
Psych 355, Miyamoto, Spr '16
How to Prove that Recency Effect Due to Retention in STM?
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How to Prove Recency Effect Is Due to Retention in STM?
• Dashed line shows effect of
counting backwards by 3’s for
30 seconds after presentation of
list.
• This result supports the
hypothesis that the recency
effect is due to retention of
recent words in STM.
mechanisms in free recall. Journal of Verbal Learning
and Verbal Behavior, 5, 351-360.
Figure 6.5
Effect of Counting Backwards
% Recalled
• Counting backwards prevents
retention of words in STM, so
recency effect disappears.
Glanzer, M., & Cunitz, A. R. (1966). Two storage
Serial Position
No recency effect
Psych 355, Miyamoto, Spr '16
How We Know that STM & LTM Are Different Mechanisms - Summary
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How Do We Know that STM and LTM
Involve Different Brain Mechanisms? (Conclusion)
• Assumption of separate STM & LTM explains facts
about the serial position curve.
• Neuropsych evidence of double dissociation between
STM & LTM.
o
o
HM & Clive Wearing
had normal memory
span, e.g., 5-8 digits
KF had reduced
memory span, e.g.,
about 2 digits.
HM, Clive Wearing
K. F.
STM
LTM
OK
Impaired
Impaired
OK
LTM was ok.
Psych 355, Miyamoto, Spr '16
Surprise Memory Test Items 19