Lecture Overview
• The Nature of Memory
• Forgetting
• Biological Bases of Memory
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The Nature of Memory
• Memory: internal record or representation
of some prior event or experience
• Memory is also a constructive process, in
which we actively organize & shape
information as it is processed, stored, &
retrieved.
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Nature of Memory: Memory Models
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Information Processing Model
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Information Processing Model—
Important Definitions
• Encoding: processing information into the
memory system (acoustic, visual, semantic)
•
selective attention
•
divided attention
•
levels of processing
•
automatic vs controlled processing
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Information Processing Model—
Important Definitions
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Storage: retaining information over time
Sensory
Short term Memory
Long term Memory
Retrieval: recovering stored information
(recall , recognition, priming; serial position
effect)
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Types of Long-term Memory
• Episodic memory (specific events: did I use
cream rinse this morning?)
• Semantic memory (knowledge of the world:
what is cream rinse, why use it?)
• Procedural memory (skill memory, specific
tasks: how do I wash my hair?)
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Types of memory (cont.)
• Explicit memory: deliberately try to remember
something
*Implicit memory: unintentional influence of
remembered stimuli
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Three-Stage Memory Model
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The Nature of Memory—
Three Stage Memory Model
• Sensory Memory: first memory stage, which
briefly preserves a relatively exact replica of
sensory information
– Sensory memory has a large capacity but
information only lasts a few seconds.
– Selected information is sent on to short-term
memory (STM).
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Two Forms of Sensory Memory
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Short-Term Memory (STM)
• Short-Term Memory (STM): second memory
stage, which temporarily stores sensory
information & decides whether to send it on
to long-term memory (LTM)
– Holds 5-9 items for about 30 seconds, but
duration improves with maintenance
rehearsal (repeat the item over and over)
– Capacity increased with chunking
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Three Stage Memory Model:
• STM: also called working memory,
reflecting that it’s more than just a
passive, temporary holding area
• Three parts of working memory:
• Visuo-spatial sketchpad
• central executive
• phonological loop
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Long-Term Memory (LTM)
• Long-Term Memory
(LTM): third stage of
memory with
relatively
permanent memory
storage & a virtually
limitless capacity
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Systems and Subsystems of LTM
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Improving LTM: Overcoming the SerialPosition Effect
• Serial-Position
Effect:
remembering
material at the
beginning & end of
a list better than
material in the
middle
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Improving LTM: Understanding
Recognition Vs. Recall
• Research shows people are better at recognizing
photos of previous high school classmates than
recalling their names.
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A Test for Recall: Can You Name Santa’s
Eight Reindeers?
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Now Try Recognizing the Names (Need
Help? Answers Appear on Next Slide)
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A) Rudolph
B) Dancer
C) Cupid
D) Lancer
E) Comet
F) Vixen
G) Blitzen
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H) Crasher
I) Donner
J) Prancer
K) Sunder
L) Thunder
M) Dasher
N) Donder
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Night Before Christmas
• To the top of the porch!
to the top of the
wall! Now dash
away! dash away! dash
away all!"
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Eight Reindeers
Prancer
Dancer
Cupid
Comet
Vixen
Donder
Blitzen
Dasher
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Forgetting: How Quickly Do We
Forget?
•
Ebbinghaus found:
– forgetting occurs
most rapidly
immediately after
learning.
– But relearning
takes less time
than initial
learning.
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Why Do We Forget? Five Key Theories
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Decay
Interference
Motivated Forgetting
Encoding Failure
Retrieval Failure
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Five Theories of Forgetting (Continued)
1. Decay Theory: memory degrades with time
2. Interference Theory: one memory competes
(interferes) with another
– Retroactive Interference (new information
interferes with recall of old)
– Proactive Interference (old information
interferes with recall of new) i.e. when
learning a third language your second
interferes .
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Examples of the Two Forms of Interference
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Five Theories of Forgetting (Continued)
3. Motivated Forgetting: motivation to forget
unpleasant, painful, threatening, or
embarrassing memories
4. Encoding Failure: information in STM is not
encoded in LTM
5. Retrieval Failure: memories stored in LTM
are momentarily inaccessible (tip-of-thetongue phenomenon)
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Four Key Factors in Forgetting
• Misinformation Effect: memory distortion from
misleading post-event information (Eyewitness
testimony)
• Source Amnesia: forgetting the true source of a
memory
• Sleeper Effect: information from an unreliable
source, which was initially discounted, later gains
credibility because source is forgotten
• Information Overload: distributed practice is better
than massed practice
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Biological Bases of Memory
•
Biology affects memory in at least two
ways:
1. Synaptic changes occur underlying
memory
2. Physiological changes influence memory
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Neuronal and Synaptic Changes
•
Long-term potentiation (LTP) =
“Neurons That Fire Together
Wire Together”
• repeated simultaneous
stimulation of a pre- and
postsynaptic neuron
strengthens connection
• Neurotransmitter release is
increased or decreased
c. 2010 i
Biological Bases of Memory
(Continued)
Physiological changes
also affect memory
(e.g., flashbulb
memories--vivid &
lasting images
associated with
surprising or strongly
emotional events).
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Where Are Memories Located?
• Memory tends
to be localized
& distributed
throughout the
brain--not just
the cortex.
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Biology & Memory Loss:
Injury & Disease
• Amnesia: memory loss
from brain injury or
trauma
• Retrograde amnesia: old
memories lost, partially
due to lack of
consolidation
• Anterograde amnesia:
new memories lost
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