Transcript Module 26

Storage: Retaining
Information
Module 26
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Storage: Retaining Information
Storage: Retaining
Information
 Sensory Memory
 Working/Short-term Memory
 Long-Term Memory
 Storing Memories in the Brain
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LO 6.2
Different models of how memory works
Menu
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Storage: Retaining Information
At the heart of memory is storage. Three
stores of memory are shown below:
Sensory
Memory
Working
Memory
Long-term
Memory
Encoding
Events
Encoding
Retrieval
Retrieval
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Sensory Memory
Sensory
Memory
Working
Memory
Long-term
Memory
Encoding
Events
Encoding
Retrieval
Retrieval
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Figure 7.5 George Sperling (1960) flashed arrays like this on a
screen for 50 milliseconds. After the display went off, a signal
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told the viewer which row to recite.
Whole Report
Sperling (1960)
R G T
F M Q
L Z S
“Recall”
RTMZ
(44% recall)
50 ms (1/20 second)
The exposure time for the stimulus is so small,
that items cannot be rehearsed.
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Partial Report
S X T
J R S
P K Y
Low Tone
Medium Tone
High Tone
“Recall”
JRS
(100% recall)
50 ms (1/20 second)
Sperling (1960) argued that sensory memory capacity
was larger than what was originally thought.
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Time Delay
A D I
N L V
O G H
Low Tone
Time
Delay
“Recall”
Medium Tone
N__
(33% recall)
High Tone
50 ms (1/20 second)
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Sensory Memory
Percent Recognized
The longer the delay the greater the memory loss.
80
60
40
20
0.15
0.30
0.50
Time (Seconds)
1.00
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Sensory Memories
Duration of sensory memory differs for
different senses.
Iconic
0.5 sec. long
Echoic
3-4 sec. long
Hepatic
< 1 sec. long
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Working Memory
Sensory
Memory
Working
Memory
Long-term
Memory
Encoding
Events
Encoding
Retrieval
Retrieval
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Working Memory
Working memory, a new
name for short-term
memory, has limited capacity
(7 ± 2 or 5-9 bits of
information) and short
duration (about 20 – 30
seconds).
George Miller
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Chunking
Capacity of working memory may be
increased by “Chunking.”
F-B-I-T-W-A-C-I-A-I-B-M
FBI TWA CIA IBM
4 chunks
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Working Memory Duration
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Long-Term Memory
Sensory
Memory
Working
Memory
Long-term
Memory
Encoding
Events
Encoding
Retrieval
Retrieval
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Long-Term Memory
Unlimited capacity store. Estimates on capacity
range from 1000 billion to 1,000,000 billion bits of
information (Landauer, 1986).
R.J. Erwin/ Photo Researchers
The Clark’s nutcracker can locate 6,000 caches of
buried pine seeds during winter and spring.
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Memory Feats
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Memory Stores
Feature
Sensory
Memory
Working
Memory
LTM
Encoding
Copy
Phonemic
Semantic
Capacity
Unlimited
7±2 Bits of
Info.
Very Large
Duration
0.25 sec.
20 sec.
Years
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Storing Memories in the Brain
1. Wilder Penfield (1967) through electrical
stimulation of the brain concluded that old
memories were etched in the brain.
2. Loftus and Loftus (1980) reviewed
Penfield's data and showed that only a
handful of brain stimulated patients
reported flashbacks.
3. Lashley (1950) using rats, suggested that
even after removing parts of the brain the
animals retained partial memory of the
maze.
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Synaptic Changes
Kandel and Schwartz (1982) Showed, in Aplysia
(California sea snail), that serotonin release
increased from neurons after conditioning.
Photo: Scientific American
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Synaptic Changes
Both Photos: From N. Toni et al., Nature, 402, Nov. 25 1999. Courtesy of Dominique Muller
Long-Term Potentiation
(LTP) refers to synaptic
enhancement after
learning (lynch, 2002).
Increase in
neurotransmitter release
or receptors on the
receiving neuron
indicates strengthening
of synapses.
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Stress Hormones & Memory
Heightened emotions (stress related or
otherwise) make for stronger memories.
Continued stress can disrupt memory.
Scott Barbour/ Getty Images
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Storing Implicit & Explicit Memories
Explicit Memory refers to facts and experiences that one
can consciously know and declare. Implicit memory
involves learning an action, and the individual does not
know or declare what she knows.
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Hippocampus
Hippocampus – a neural center in the limbic
system that processes explicit memories.
Weidenfield & Nicolson archives
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Anterograde Amnesia
After losing his hippocampus in surgery, patient
HM remembers everything before the operation but
cannot make new memories. We call this
anterograde amnesia.
Anterograde
Amnesia
(HM)
Memory Intact
No New Memories
Surgery
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Implicit Memory
HM is unable to make new memories that are
declarative (explicit) but he can form new
memories that are procedural (implicit).
A
B
C
HM learnt the Tower of Hanoi (game) after his surgery. Each time he
plays it he is unable to remember the fact that he has already played
the game.
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Cerebellum
Cerebellum – a neural center in the hindbrain
that processes implicit memories.
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