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PSY 445: Learning & Memory
Chapter 8:
Short-Term Retention
Short-Term Retention
Retention over short intervals of time
Some History
James (1890)
Primary Memory
• Memories that have never left consciousness
Secondary Memory
• Memories that have been absent form
consciousness and therefore belong to the
psychological past
Short-Term Retention
Waugh & Norman (1965)
• Reintroduced the primary-secondary distinction
Primary Memory
• Holds only a few items for only a few seconds; forgetting
occurs rapidly if rehearsal is prevented
• Addition of new items requires displacement of some other
item already stored
Secondary Memory
• Information that is available for future recall
These researchers proposed the following:
• The fact that you can recall something immediately after
presentation does not mean it has entered secondary memory
• Recall can come from primary memory, secondary memory, or
both
Two Memory Stores
Atkinson & Shiffrin (1968, 1971)
• Dual-Store Theory (1968) renamed Modal Model (1971)
• Renamed because it became the prototype of other
theories
• Short-Term Store (STS)
• Long-term Store (LTS)
Atkinson & Shiffrin’s (1971) Modal Model
Sensory Registers
• Detect sensory input from the various modalities
• Visual, auditory, haptic, etc.
• Memories are held for only a few hundred milliseconds
Short-Term Store
Lasts a few seconds and is made up of:
• Temporary working memory
• Control processes:
• Rehearsal
• Coding
• Decisions
• Retrieval strategies
Long-Term Store
• Permanent memory store
Two memory stores are not enough…
Baddeley & Hitch (1974)
• Proposed a model of working memory – a system
that supports complex cognitive activities like
reasoning instead of just short-term storage
STM Tasks
Brown-Peterson Distractor Task (Brown, 1958;
Peterson & Peterson, 1959)
Procedure
• Read three letters, then a number
• Begin counting backwards by 3’s
• Counting backwards prevented the rehearsal of the
letters
• After a set time, recall three letters
Results
• Recall drops dramatically after just a few seconds
See next slide 
Brown-Peterson Distractor Task
Peterson & Peterson (1959)
3 sec delay  recall rate 80%
18 sec delay  recall rate 10%
Brown-Peterson Distractor Task
Why the quick forgetting?
• Memory trace vanished because of decay during
the passage of time after hearing the letters
• Closely spaced trials lead to poorer recall;
susceptibility to interference
Proactive Interference seems to be a problem
• Cumulative memory seems to be occurring as
memory form previous lists may be hampering
recall
• Information learned previously interferes with
learning new information: seems to build up across
trials
Types of Interference
Proactive Interference
• The disruptive effect of prior learning on the recall of new
information (old materials increasing the forgetting of new
materials)
Retroactive Interference
• The disruptive effect of new information on the recall of
previous information (new materials increasing the forgetting
of old materials)
Time 1
Time 2
Study French Study Spanish
Study French Study Spanish
Test
Recall Spanish
Recall French
Interference
Proactive
Retroactive
Brown-Peterson Distractor Task
Why the quick forgetting?
• Similarity of items causes additional interference with
recall
• If the words come from the same semantic category ,
performance declines even more across trials
• HOWEVER, if after several trials the category of
target words is changed, recall increases
dramatically:
Release From Proactive Interference
• When previously learned information no longer
interferes with new information
See next slide 
12
Wickens et al. (1976): Procedures
13
Wickens et al. (1976): Results
Trial 4: There is a release of Proactive Interference
Memory Span
 The longest sequence of items
that can be recalled after a single
presentation
 Recall is attempted immediately;
no delay or distractors
 Typically letters, numbers, or
words are used
George Miller
(1920-2012)
Miller (1956):
“The Magic Number” 7 +/- 2 items
His book
Memory Span
Conrad (1958)
Procedure
• Asked postal workers to listen to and then recall
7, 8, and 9 digits
Results
• 80% recall with 7 digits
• 50% recall with 8 digits
• 25% recall with 9 digits
Interpretation
• Successful replication of Miller’s basic research
as average human memory is approximately 5 to
9 items
Memory Span: The Word-Length Effect
Baddeley, Thomson, & Buchanan (1975)
•
Memory for lists of words is better for short words
than for long words
•
It takes longer to rehearse long words and to
produce them during recall
Characteristics of Verbal Short-Term Retention
There are several objective features of STM that
distinguishes it form LTM
• Acoustic Encoding
• Limited Capacity
• Limited Duration
• Susceptibility to Forgetting
• Transfer to LTM
Acoustic Encoding
Short-term memory relies primarily on an
acoustic rather than semantic or visual code
• Word are remembered as they sound – as if they
were being verbally rehearsed
If words are encoded by sound sound-alike
substitutions (errors) are likely
• In serial-recall tasks errors occur when participants
substitute letters that sounded like the correct letters
(e.g. B for P)
19
Acoustic Encoding
Conrad (1964)
• Showed participants letters on the screen to
remember
• Errors made were close to the letter’s sound, not
appearance
• Example: F was mistaken as S or X, not P
Limited Capacity
Miller (1956)
Posited that we could enlarge the “magic number”
by increasing the amount of information contained
within each item
Not absolute digits or letters that you remember but
groups (chunks) of things that you remember
Chunking
Organizing information into meaningful units so that
it can better be remembered
Chunking Helps Increase Limited Capacity
Chase & Simon (1973)
Procedure
• Chess master vs. beginners
• Memorize chess pieces positioned for a real chess
game for 5 seconds
• Reproduce the arrangement shortly after
Garry Kasparov is best known as the
world's greatest living chess player
But he lost to Deep Blue
Click on picture for video 
Chunking Helps Increase Limited Capacity
Procedure
• You have 5 seconds to
memorize as much as
you can
• Then, draw an empty
chess board and
reproduce the
arrangement of pieces
Chase & Simon (1973)
Procedure
Actual Game
Random Game
Chase & Simon (1973)
Chase & Simon (1973)
Results
Results
(a) The chess master is
better at reproducing
actual game positions
(b) Master’s performance
drops to level of beginner
when pieces are arranged
randomly
Chunking Helps Increase Limited Capacity
Chase & Simon (1973)
Results
• Chess master did much better than novices on actual game board
• The chess master’s advantage vanished when the board was
arranged randomly – familiar patterns were destroyed
Interpretation
• Chess master did not have a superior STM (as some had
suggested); rather he had stored many of the patterns that occur in
real chess games in LTM
• He saw the layout of chess pieces not in terms of individual pieces
but in terms of 4-6 chunks, each made up of a group of pieces that
formed familiar, meaningful patterns
• The chess master’s advantage vanished when the board was
arranged randomly – familiar patterns were destroyed
Chunking Helps Increase Limited Capacity
Ericcson et al. (1989)
• College student had an initial digit span of 7
• After 230 one-hour training sessions for 2 years, he
could remember up to 79 digits
How did he do it?
• By combining the numbers with meaningful sets:
• 3 4 9 2  record for mile (3 min 49.2 sec)
• 8 1 1 0  almost emergency (9 1 1)
• 8 9 3  very old man, 89.3
Limited Duration
• Without maintenance rehearsal, something stays in
STM for between 15-30 seconds
Forgetting: STM is Sensitive to Disruption
Forgetting from STM is believed to be due to
spontaneous fading of the memory trace over
time or to the displacement of old items by new
items
• Does not take much to disrupt STM
See next slide 
Forgetting: STM is Sensitive to Disruption
Crowder (1972)
Procedure
• Hear list of nine items
• Final auditory stimulus as cue to recall
• “Suffix”: zero or buzzer
Results
• Zero-suffix: 50% more errors on last item
Interpretation
• Zero-suffix: Increases list length referred to it as the “suffix effect”
Note: Other studies have seen the suffix effect take place
among participants with hearing loss who are using sign
language
Transfer to LTM
STM appears to help in the transfer of information
into LTM
• Several multistore theories suggest that retention in
STM allows the opportunity for information to be
transferred or copied into LTM – much consensus on
this
Other Modalities of STM
Most STM testing in auditory and verbal material
Here are some other modalities used to test STM
• Visual STM
• Spatial STM
• STM for Actions
• STM for Odors
• STM in the Hearing Impaired
Visual STM
To study visual STM:
Typical Procedure
Acquisition Phase
• Stimuli are presented as short lists of images
(pictures, slides, etc.)
• Images may be meaningless or meaningful
Typical Test Phase
• A test picture is presented and the participant decides
whether it was in the previous list
Spatial STM
To study Spatial STM:
Procedure
Typical Acquisition Phase
• Spatial positions illustrated by using computer
screen
• Asterisk is presented in one square at a time
(random sequence)
Typical Test Phase
• Participants attempt to point to locations in the same
order in which they appeared
STM for Actions
To study STM for Actions:
Procedure
Typical Acquisition Phase
• Movement triplets are presented to participants
• Varying delays; varying distractors
Typical Test Phase
• Participants attempt to recall in order the actions
STM for Odors
To study STM for Odors:
Procedure
Acquisition Phase
• List of odorants is presented
Test Phase
• Participants attempt to recognize test odorants
STM for the Hearing Impaired
People sometimes recode from one modality to another
• Hearing impaired participants are used to test this
Procedure
Typical Acquisition Phase
• Hearing participants will be tested using words; hearingimpaired will be tested using signs
Typical Test Phase
• Compare the two groups to determine differences
Limitations: varying levels of hearing impairment; amount
of training in oral speech; varying degrees of expertise in
different types of sign language
Working Memory (WM)
Refers to the system for temporarily maintaining
mental representations that are relevant to the
performance of a cognitive task in an activated state
• More than just a storage system
Reading span measures the capacity of working
memory when attention must be paid to
comprehension of sentences and to remembering a
list of words
38
Working Memory: Modern STM
Baddeley & Hitch (1974)
Updated the STM model
Working Memory
• Limited capacity system for temporary storage and
manipulation of information for complex tasks such
as comprehension, learning, and reasoning
1.
2.
Working memory consists of a number of parts
Working memory helps us manipulate
information to carry out complex tasks, not
just store information
Models of Working Memory
Baddeley & Hitch (1974)
Original model proposed a phonological loop and a visualspatial sketch pad coordinated by a central executive
Models of Working Memory
Later Baddeley added a fourth component (episodic buffer)
• The phonological loop stores and rehearses verbal representations
whereas the sketch pad does the same for visual/spatial
representations.
• Central executive focuses and switches attention, supervises and
coordinates the storage components, and retrieves representations
from long-term memory
• Episodic buffer connects WM to LTM
Baddeley (2001)
41
Phonological Loop
Brief storage of verbal material
Remember: STM primarily uses auditory coding
Made of two parts:
Storage
• Passive, holds information
• Decays in about 2 seconds without rehearsal
Rehearsal
• Active
• Repeats information in storage to prevent decay
42
Visuospatial Sketch Pad
Holds visual and spatial information
• Used in doing anything visual - puzzles, drawings,
etc.
43
Central Executive
Pulls information from LTM and coordinates tasks
• Uses information from the phonological loop and
visuospatial sketchpad
• Focuses on specific parts of task
• Switches attention from one part to another
44
Episodic Buffer
This integrates information across:
1. The phonological and visual stores
2. The operations of the central executive
3. Information entry and retrieval from LTM
Is there really a separate STM?
Neuropsychological Dissociations
• Studies of individuals with impairment of auditory-verbal STM
indicate they have different sites of brain injury than do patients
without STM losses
Mishkin & Appenzeller (1987)
• Found that damage to the combined hippocampus and amygdala
impaired short-term retention of objects recently shown to a monkey,
but did not prevent long-term learning of objects
• They gave food reward for correct response
• STM task – monkey could not remember which of two objects had
just been shown
• LTM task – monkey could learn which of two objects was paired
with food
A Single-Memory Approach?
An alternative explanation to the two-store
memory theories suggests that we have a single
set of memories – but memories can differ
between those that are currently active and those
that are inactive
• This idea has not gained acceptance
Credits
Some of the slides in this presentation prepared with the assistance of
the following web sites:
 www.csupomona.edu/.../PSY335%20PPTs/Baddeley/BChap3....