Transcript Memory

Storage
Chapter 8, Lecture 3
“So, despite the brain’s vast storage capacity,
we do not store information as libraries store
their books, in discrete, precise locations.”
- David Myers
Storage: Retaining Information
Storage is at the heart of memory. Three
stores of memory are shown below:
Sensory
Memory
Working
Memory
Long-term
Memory
Encoding
Events
Encoding
Retrieval
Retrieval
Sensory Memory
Sensory
Memory
Working
Memory
Long-term
Memory
Encoding
Events
Encoding
Retrieval
Retrieval
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.
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.
Time Delay
A D I
N L V
O G H
50 ms (1/20 second)
Low Tone
Time
Delay
“Recall”
Medium Tone
N__
(33% recall)
High Tone
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
Sensory Memories
The duration of sensory memory varies for the
different senses.
Iconic
0.5 sec. long
Echoic
3-4 sec. long
Hepatic
< 1 sec. long
Working Memory
Sensory
Memory
Working
Memory
Long-term
Memory
Encoding
Events
Encoding
Retrieval
Retrieval
Working Memory
Working memory, the new name for short-term
memory, has a limited capacity (7±2) and a short
duration (20 seconds).
Sir George Hamilton observed that he could accurately
remember up to 7 beans thrown on the floor. If there were
more beans, he guessed.
Capacity
The Magical Number Seven,
Plus or Minus Two: Some
Limits on Our Capacity for
Processing Information (1956).
Ready?
MUTGIKTLRSYP
You should be able to
recall 7±2 letters.
George Miller
Chunking
The capacity of the 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
Duration
Peterson and Peterson (1959) measured the
duration of working memory by manipulating
rehearsal.
CHJ
MKT
HIJ
547
547
544
541
…
CH??
The duration of the working memory is about 20 sec.
Working Memory Duration
Long-Term Memory
Sensory
Memory
Working
Memory
Long-term
Memory
Encoding
Events
Encoding
Retrieval
Retrieval
Long-Term Memory
Essentially unlimited capacity store.
R.J. Erwin/ Photo Researchers
The Clark’s nutcracker can locate 6,000 caches of
buried pine seeds during winter and spring.
Memory Feats
Memory Stores
Feature
Sensory
Memory
Working
Memory
LTM
Encoding
Copy
Phonemic
Semantic
Capacity
Unlimited
7±2 Chunks
Very Large
Duration
0.25 sec.
20 sec.
Years
Storing Memories in the Brain
1. Loftus and Loftus (1980) reviewed previous
research data showing, through brain
stimulation, that memories were etched into
the brain and found that only a handful of
brain stimulated patients reported
flashbacks.
2. Using rats, Lashley (1950) suggested that
even after removing parts of the brain, the
animals retain partial memory of the maze.
Synaptic Changes
In Aplysia, Kandel and Schwartz (1982) showed
that serotonin release from neurons increased
after conditioning.
Photo: Scientific American
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). An increase
in neurotransmitter release
or receptors on the
receiving neuron indicates
strengthening of synapses.
Stress Hormones & Memory
Heightened emotions (stress-related or
otherwise) make for stronger memories.
Flashbulb memories are clear memories of
emotionally significant moments or events
Scott Barbour/ Getty Images
Beryl Benderly has described “flashbulb”
memories this way: “It’s as if our nervous
system takes a multimedia snapshot of the
sounds, sights, smells, weather, emotional
climate, even the body postures we experience
at certain moments.”
In a sentence or two, write down your
three most vivid memories…
The percentage of Duke students who had flashbulb
recollections of each event:
A car accident you were in or witnessed
When you first met your college roommate
Your high school graduation
Your senior prom
An early romantic experience
A time you had to speak in front of an audience
When you got your admissions letter from college
The day President Reagan was shot in Washington
Your first flight
The moment you opened your SAT scores
Your seventeenth birthday
The last time you ate a holiday dinner at home
Your first college class
The first time your parents left you alone at home
Your thirteenth birthday
(85)
(82)
(81)
(78)
(77)
(72)
(65)
(52)
(40)
(33)
(30)
(23)
(21)
(19)
(12)
Storing Implicit & Explicit Memories
Explicit Memory refers to facts and experiences that one can
consciously know and declare. Implicit memory involves
learning an action while the individual does not know or
declare what she knows.
p. 343
Hippocampus
Hippocampus – a neural center in the limbic
system that processes explicit memories.
Weidenfield & Nicolson archives
Anterograde Amnesia
After losing his hippocampus in surgery, patient
Henry M. (HM) remembered everything before the
operation but cannot make new memories. We call
this anterograde amnesia.
Anterograde
Amnesia
(HM)
Memory Intact
No New Memories
Surgery
Different from retrograde amnesia, which is loss of
memory from before an event or injury.
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 learned 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.
Cerebellum
Cerebellum – a neural center in the hindbrain
that processes implicit memories.
Homework
Read p.345-349
“At any given moment, we can consciously
process only a very limited amount of
information.”
- David Myers