Memory
Memory
Three Stages of Memory:
An Information-Processing View

Information processing theories
◦ Brain and computer operations are similar

Information-processing model
◦ Operations: input, storage, and retrieval
◦ Variety of control mechanisms at each
point
Information-Processing Theory
Sensory
information
STORAGE
economics literature
INPUT
RETRIEVAL
Information is
taken into brain
Information is used
as basis of behaviors
and interactions
culture science
religion
history
math
Information gets
processed, analyzed,
and stored until use
Memory
Memory

Information-processing model
◦ Information enters through sensory
receptors
◦ Attention selects information to be entered
◦ Information encoded for next memory
stage
◦ Some memory is saved, other information
is lost or discarded

Stage theory of memory
◦ Assumes humans have 3-stage memory
lasts less Discarded
than a
second,
interprets
stimulus
Stimuli
(input)
Sensory
Register
Discarded
Working
Memory
(Short-term
Memory)
Long-Term
Memory
(increasing
or
decreasing
availability)
Response
(output
or
reaction
behavior)
Control Processes
(selective attention, emotional regulation, strategic thinking)
Memory
Stages of Memory

Sensory register
◦ Holds image or experience until processing
◦ Can last up to 4 seconds; usually lasts less

Short-term memory (STM)
◦ Usually attention transfers information from
sensory register to STM
◦ Usually information lasts less than one
minute unless control processes like
rehearsal and chunking are used
Demonstration
Attend to the words in the green box as they flash
on the screen. When the last word disappears,
write down as many words as you can recall.
TABLE
SNOW
FOOT
DOG
SON
END
HAT
BUS
BREAD
DOOR
CAT
Memory
Stages of Memory
◦ Rehearsal – mental repetition of
information
 Humans have preference for transforming
information into acoustic codes or sounds
◦ Chunking – grouping information into bits
 Capacity limited to 7 items plus or minus 2
 Rare to hold between 5 and 9 items in STM

STM functions
◦ Temporary storage of information
◦ Serves as working memory: space used for
retrieved memories from long-term memory
Accuracy of recall for a single group of
three consonants declines rapidly when
subjects are prevented from rehearsing
by being asked to count backwards
Percent of accuracy of recall
100
80
60
40
20
0
0
3
6
9
12
Interval before recall in seconds
15
18
Memory
Stages of Memory
Differences between LTM and STM

Volume: vast
amount
◦ Indexed and
retrieved selectively
by cues
• Type of information
– In terms of meaning
or semantic codes
• Durability
 Processing location
– Appears to be
◦ STM – frontal lobes
permanent,
of cortex
forgetting occurs
◦ LTM – hippocampus
then transferred to
other brain areas
Memory
Types of Long-Term Memory

Procedural
◦ Memory for skills and procedures
(how to)

Episodic
◦ Information about time and
places (when, where)

Semantic
◦ Memory for meaning
(importance)
Memory
Long-Term Memory

Long-term memory
◦ Storehouse for almost unlimited
information over long periods of time
◦ Easy to store procedural and semantic
memories, but stores episodic
information less well
◦ Semantic and episodic memories grouped
together as declarative memory
Types of Long Term Memory
Declarative memory
Semantic memory
“I know what
a guitar is.”
Procedural memory
Episodic memory
“I remember buying
my first guitar.”
“I remember how
to play a guitar.”
Memory
Organization in Long-Term
Memory

Organization eases retrieval process
◦ Grouped into categories
◦ Associative network: memories linked
together through experience
◦ Spreading activation model: representations
of concepts and their characteristics are
activated (ie: canary and bird)
 Closeness of association affects retrieval time –
distant associations take longer
Example of Associative Links
Tiger
Cat
Animal
Skin
Dog
Breathes
Pat
Sparrow
Bird
Canary
Green
Robin
Ostrich
Red
Orange
Feathers
Yellow
Sings
Memory
Retrieval of Long-Term Memories

Frustration of unable to retrieve
information

Three ways to test retrieval
◦ Recall method:
recall
cues or hints used for
◦ Recognition method: select correct from
alternative information (ie: multiple choice)
◦ Relearning method: relearn previous
learned information
Memory
Serial Learning

Order of memorizing is as important as
items on the list

Serial position effect – better recall
of items at beginning and end of lists
◦ Affected by timing or delay of recall
◦ Involves simultaneous use of STM and LTM

Tip-of-the-tongue phenomenon
◦ Most recall occurs within a few minutes
Effects of Recall Timing on Short-Term Memory
80
Tested immediately
Test delayed 20 seconds
Proportion correct
70
60
50
40
30
20
0
1
2
3
4
5
6
7
8
9
10
Position in original list
11 12 13 14 15
16
Memory
Levels of Processing:
An Alternative to the Stage
Model

Two levels of memory processing

Distinction between STM and LTM
◦ Matter of degree, not separate stages
◦ Differing levels of processing during
encoding process
Memory
Levels of Processing:
An Alternative to the Stage
Model

Processing continuum
◦ Shallow level – processed briefly
◦ Deeper level – processed much deeper
involves greater elaboration (creating
more associations between new and
existing memories)
 An excellent way to improve memory
Memory
Forgetting and Why It Occurs

Decay theory
◦ Unused memories fade gradually over
time
◦ Causes of forgetting
 fading memory traces over time
 Interference with retrieval
Memory
Forgetting and Why It Occurs

Interference theory
◦ Other memories interfere with retrieval
◦ Interference mostly from similar memories

Types of interference
◦ Proactive – interference from prior learning
◦ Reactive – interference from later learning
Memory
Forgetting and Why It Occurs

Interfering with STM
◦ Overloading STM capacity or weakening/
blocking an item out of storage

Interference with LTM
◦ Interference plays lesser role in disrupting
semantic memories than in episodic
memories
Memory
Reconstruction (Schema) Theory

Schemas – associative networks of
beliefs, knowledge, and expectations
◦ During retrieval process, LTM information
recalled in distorted and incorrect manner
that is consistent with our schemas
 May occur because brain stores meaning better
than episodic details
 May result in false memory – recalling
something that never happened
Memory
Motivated Forgetting

Freud: some threatening information is
repressed – pushed into
unconsciousness

Emotional arousal improves memory in
some ways or has little effect on
memory
◦ Mild levels of positive and negative arousal
appear to enhance memory
◦ Emotion-laden violence on TV programs
decreases recall of program advertisements
Memory
Human Diversity: Cultural
Circumstances and Memory Skills

Kearins – environmental demands
and culture may influence type of
memory used
◦ Aboriginals have better visual memory
skills
Memory
Biological Basis of Memory

Synaptic theories of memory
◦ Physical change must occur in nervous
system
◦ Engram: something remaining after
learning
◦ Synaptic facilitation (Hebb) is biological
basis of learning and memory
 Individual experiences produce unique patterns
of neural activity causing structural changes in
synapses
Memory
Biological Basis of Memory

Synaptic theories of memory
◦ Classical conditioning of snails (Kandel)
 Amount of neurotransmitter in synapse
increased – synapse holds memory
 Drugs that interfere with protein synthesis
block memory formation
 Consolidation – fragile memories grow
more permanent over a few minutes
Memory
Stages of Memory and the Brain

STM and LTM differences in brain
◦ In role of synaptic changes: synapse
changes involved in LTM but not STM
◦ In brain structures involved
 Three stages of memory involve various
structures of brain as information is stored
and retrieved
◦ Allows memory recall with visual images or
auditory sensations
Memory
Amnesia: Disorders of Memory

Retrograde amnesia
◦ No memory of what happened immediately
before an accident or highly stressful event
 Little or no disruption in STM
 New long-term memories can be formed
 Usually memory loss does not last lifetime
 Stress of event disrupts consolidation and
retroactive interference blocks retrieval
Memory
Amnesia: Disorders of Memory

Anterograde amnesia
◦ Inability to store and retrieve new
information
◦ Case of H.M. – epilepsy and neurosurgery
 Does not affect procedural memory abilities but
disrupts episodic memory formation
 Hippocampus involved in episodic memory
◦ Damage prevents formation of new long-term
declarative memories
Memory
Amnesia: Disorders of Memory

Korsakoff’s syndrome
◦ Brain disorder from prolonged loss of vitamin
thiamine as in diet of chronic alcoholics
◦ Extreme degree of memory loss
◦ Often engage in confabulation – cannot
remember ending to a statement so make it
up; an exaggerated version of normal
reconstruction distortion
Memory
Inaccurate Recall Due to Biased
Questioning

Research on eyewitness information
◦ Can be potent source of distortion
 Interviewer questions can contain cues that
influence retrieval
 Reconstruction theory of forgetting – people
remember something that did not occur
because it seemed consistent with the event
 Perceived expertise of interviewer may bias
informational response
Memory
Inaccurate Eyewitness Recall

Eyewitness testimony frequently
inaccurate
◦ Children, adolescents are particularly
suggestible when interviewed by adults
 Sometimes describe what never happened
 Neutral questions get best results

Eyewitnesses who look but do not
see
◦ Some things processed in shallow ways due
to inattentiveness or lack of importance
attached
Memory
Stereotypes and Eyewitness
Testimony

Allport: memories distorted by prejudices
◦ Research in US – common African American
names more stereotyped with criminality when
memories fit personal schemas of prejudice

Inaccurate recall due to characteristics of
the eyewitness
◦ Being tired, upset, intoxicated may effect recall
◦ Drunk eyewitness: visual recall may be accurate
in some circumstances
Memory
Recall of Repressed Memories of
Sexual and Physical Abuse

Most compelling testimony is from
victims
◦ Many cases of repressed memories when
adult was abused as child now in media
 Dilemma - hard to know what is accurate
 Many traumatic childhood memories
discovered in psychotherapy may be false
memories
Memory
Hypnosis and Eyewitness
Testimony

Hypnotizing witnesses to crimes is
controversial
◦ Hypnotic age regression: hypnotized
person goes back in time to earlier age –
relives event and recalls forgotten
experiences
 May be heightened imagination more than
accurate relived memories
◦ Hypnotized witnesses to recent crimes may
have more accurate recall
Memory
Improving the Accuracy of
Eyewitnesses’ Testimony

Thousands of experiments in research
have raised concerns but little has
been done
◦ DNA saved innocent persons on death row
convicted on eyewitness testimony
◦ U.S. Dept. of Justice made
recommendations in 1999 about use of
eyewitness testimony
Memory
Eyewitness Testimony

Recommendations
◦ Establish good rapport
◦ Ask open-ended questions
◦ Use fillers in lineup fitting witness
description
◦ Place only one suspect in identification
lineup
◦ Unbiased instructions to eyewitnesses
before viewing photos and lineups
◦ Avoid giving feedback to eyewitnesses after
identification of photo or person in lineup
Memory
The End