Transcript PSY 368 Human Memory - the Department of Psychology at Illinois

PSY 368 Human
Memory
Development of Memory
Development of Memory
• Outline for this week
• Studying infants & children
• Basic Processes and Capacities
• Methodological issues
• Memory in the Elderly
• What abilities decline?
• Why do they decline?
Studying Young Kids
• Iconic memory
• Sheingold (1973) replicated Sperling with kids (5, 8, 11, and
adults)
• Array of 7 shapes; central
pointer
• flashed briefly (100 msec), then
pointer
• what was pointer pointing at?
• varied delay between pointer and
array: simultaneous, 0 (right after
disappeared), 50, 100, 150, 200,
250, 500, 1000 msec
Studying Young Kids
• Iconic memory
• Sheingold (1973) replicated Sperling with kids (5, 8, 11, and
adults)
• Results:
• at 50 msec delay, no age effects
• Conclusion:
• 5-years-olds can hold lots of info
in sensory memory
• capacity of sensory memory
doesn’t develop
• There were changes at other delays, suggesting differences in other
stages of processing
Developing Memory
• Short-term memory
• Span
• Serial position
• Encoding strategies
• Rehearsal
• Organization
• Elaboration
• Attention
Developing Memory
• Short-term memory: Span
Mean Number Recalled
• The number of items that children can recall on the
digit span task increases from around 2.5 at age 2, to 7
in adulthood
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9
8
7
6
5
4
3
2
1
0
Numbers
Letters
0
5
10
Age
15
Developing Memory
• Short-term memory: Span
• According to proponents of the working memory model, the
duration of the phonological loop is a key constraint of how
much information can be remembered
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Mean Number Recalled
• Correlation
between speech
rate and memory
span
• But Cowan (1997),
suggests that search
time may also play
a role (reflected in
pauses btwn words)
Hulme et al (1984)
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5
4 years
7 years
10 years
Adult
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3
2
1
0
0
1
2
3
4
Speech rate (words/sec)
5
Developing Memory
• Short-term memory: Serial position curve
• 6-years-olds show recency but not primacy, 9-year-olds show some
primacy
High
Recall
• May reflect
different
encoding
strategies
Low
Recall
14+ years old
9-year-olds
6-year olds
Early ------------------------------------------------------ Late
(Primacy)
(Recency)
Developing Memory
• Short-term memory: Encoding strategies
• Young children seem to be less efficient at encoding
information (little or no primacy), probably due to
differences in strategy usage
• Rehearsal: repetitively naming information that is to be
remembered
• Organization: information to be remembered should be structured
so that related information is placed together
• Elaboration: embellishing information to be remembered to make
it more memorable
Developing Memory
• Short-term memory: Rehearsal
• Flavell, Beach, & Chinsky (1966)
• Presented kindergarten, 2nd, and 5th grade children with sets of
pictures of common objects and asked them to remember them.
• During 15-sec. delay before each recall test, observed children's lip
movements
Developing Memory
• Short-term memory: Rehearsal
• Flavell, Beach, & Chinsky (1966)
• Results
• Both recall and rehearsal increased with age
• 10% of kindergarteners ---> 85% of grade 5 children.
• Also, within a grade level, children who rehearsed more recalled
more.
• Conclusions
• Rehearsal increases with age, and the frequency of rehearsal
determines memory performance
Developing Memory
• Short-term memory: Rehearsal
• Ornstein, Naus, & Liberty (1975)
• Used an overt rehearsal procedure with 3rd, 6th, & 8th grade
children:
• Children were presented with a series of words, and told that they
must repeat the most recently-presented word during the
interstimulus interval (ISI), and that if they wish they may also
practice other words during the ISI.
Developing Memory
• Short-term memory: Rehearsal - type changes with age
• Ornstein, Naus, & Liberty (1975)
Word
Presented
Eighth-grade student
Third-grade student
1. Yard
Yard, yard, yard
Yard, yard, yard, yard
2. Cat
Cat, yard, yard, cat
Cat, cat, cat, cat, yard
3. Man
Man, cat, yard, man,
cat, yard
Man, man, man, man,
man
4. Desk
Desk, man, yard, cat,
man, desk, cat, yard
Desk, desk, desk, desk
Developing Memory
• Short-term memory: Organization - organizing the
items we want to remember into meaningful categories
• Salatas & Flavell (1976)
• Presented 1st graders with 16 pictures (4 from each of 4
categories).
• Experimenter named the pictures, identified the categories,
and placed the pictures randomly in front of the children.
• Children were told to (physically) sort the pictures in a way
that would help them remember them.
• Result:
• Only 27% of the children sorted the cards according to category.
Developing Memory
• Short-term memory: Organization - organizing the
items we want to remember into meaningful categories
• Other, similar studies have found that:
• Preschool children tend not to use this strategy - children as
old as 8 years often fail to group the cards on the basis of
meaning (instead, they group items randomly)
• In the early school years, children do not spontaneously use
the strategy, but they can be taught it and benefit from using it.
• By the age of 10 or 11 are more likely to group on the basis of
meaning, and they recall more items
Developing Memory
• Short-term memory: Elaboration
• Generating relations between pairs of items so that memory for
the items can be constructed in a meaningful way
• Elaboration is not spontaneously used as a memory strategy
until adolescence, and even then it is not common
• Younger children can be taught to use elaboration but they do
not get the same benefits with respect to increased recall as older
children
Brief Summary
• Short-term memory: Encoding Strategies
• Memory development between preschool years &
adolescence involves age-related changes in the frequency
of use and quality of strategies
• Acquisition of new strategies, refinement of existing, &
generalization to new situations
Developing Memory
• Attention - Ability to selectively attend (and inhibit irrelevant)
develops with age
• Hagen & Stanovich (1977):
• Presented Pairs of pictures
• Ignore one & remember the other
• Intentional Test: recall the central stimuli, as per instructions – recall
increases with age
• Incidental Test: recall the ones they were supposed to ignore
• Results:
• smaller age differences: after age 11, actually remember less of the to-beignored items
• Conclusion: younger kids paying attention to irrelevant stimuli
more than older kids
Developing Memory
• LTM - Use of content knowledge
• Bauer & Mandler (1992)
• tested babies 11.5 to 20 months
• shown a sequence of events
• later allowed to interact with the materials
• e.g., putting a ball in a cup, inverting another cup on top, shaking
cups
• children re-enacted events in sequence shown
Developing Memory
• LTM - Use of content knowledge – scripts
• Hudson & Nelson (1983)
• Told children (4 & 5 yr olds) a story about a birthday party, but put
some elements in wrong order
• When asked to recall the
stories, children often
omitted or corrected the
miss-ordered items
Developing Memory
• LTM - Use of content knowledge
• Chi (1978)
• 10 yr old chess experts vs.
novice adults
• For the children with chess
expertise, an assortment of
shaped pieces on a chequered
board was not a random array
of objects, but a meaningful
situation encompassing
multiple relationships between
the pieces
Developing Memory
• LTM - Use of content knowledge
• Dinosaur knowledge studies (Chi & Koeske, 1983; Gobbo &
Chi, 1986)
• 5 dinosaur child experts & 5 child novices
• Showed pictures of dinosaurs, asked them to
tell all they knew about the pictured dinosaur
• Experts and novices produced similar numbers
of explicit propositions (which could be seen
directly in pictures)
• Experts produced many more implicit
propositions (which could not be seen in the
pictures)
Brief Summary
•
•
•
•
Recall and Recognition developed early
Implicit memory developed early
Episodic last to develop
STM
• Increase in strategies - rehearsal, organization
• LTM
• Increase in general knowledge over first 15 yrs
• Kids use scripts & schemata
Development of Memory
• Outline for this week
• Studying infants & children
• Basic Processes and Capacities
• Methodological issues
• Memory in the Elderly
• What abilities decline?
• Why do they decline?
• Brain change
• Cognitive Changes
• Episodic Memory
• STM/WM
• Implicit Memory
• Strategies
• Theories
The Aging Brain
• On average, the brain shrinks 5% to 10% between the ages of 20 and 90
• May result from a decrease in dendrites, damage to myelin sheath, or the
death of brain cells
• Some areas of the brain shrink more than others
Region
As we age, this region …
Overall brain
Shrinks
Ventricles
Expands
Frontal lobes
Shrinks most rapidly
Temporal lobes
Shrinks slowly
Hippocampus
Occipital lobes
Shrinks slowly, then accelerates
(possibly due to disease)
Loses 20–30% of its neurons by
age 80
Shrinks slowly
The Aging Brain
• On average, the brain shrinks 5% to 10% between the ages of 20 and 90
• May result from a decrease in dendrites, damage to myelin sheath, or the
death of brain cells
• Some areas of the brain shrink more than others
• Shrinkage of the prefrontal cortex is linked with a decrease in working
memory and other cognitive activities
• A general slowing of function in the brain and spinal cord begins in middle
adulthood and accelerates in late adulthood
• Aging has been linked to a reduction in the production of certain
neurotransmitters
The Aging Brain: Adapting
As the brain ages, it adapts in several
ways:
• Neurogenesis: the generation of new
neurons throughout the life span
• Dendrite growth increases from the 40’s
to 70’s
• Older brains rewire to compensate for
losses
• Hemispheric lateralization can decrease;
may improve cognitive functioning
Aging: Episodic Memory
• Episodic memory declines steadily through the adult
years, across many task:
• Verbal and visual materials
• Rivermead Behavioural Memory Test (everyday memory
situations)
• Memory for card hands
• Memorizing passages
• Memory for conversations
• The magnitude of the decline depends on the nature of the
task and the method of testing (recall vs recognition).
Aging: Episodic Memory
• Episodic memory declines steadily through the adult years
• Recall and recollection tests
Mean Number Recalled
• Age effects are clearest in recall tests, which lack external cues,
while recognition tends to be relatively preserved in the elderly.
• Recall - 20% over 40 yrs (25-65)
• Recognition - little decline
100
90
80
70
60
50
40
30
20
10
0
Recall
Recognition
Young
Old
Age
Aging: Episodic Memory
• Episodic memory declines steadily through the adult years
• Recall and recollection tests
• Age effects are clearest in recall tests, which lack external cues,
while recognition tends to be relatively preserved in the elderly.
• This difference may reflect a combination of:
• Fewer retrieval cues in the recall task
• A greater involvement of association in free recall
• Taking longer to perceive and process materials
• Whether recognition is impaired or not depends on the nature of the
task:
• If familiarity (“knowing”) is sufficient—no deficit
• If recollection (“remembering”) is necessary—some impairment
• Source memory impairments: when and where information is learned
Aging: Episodic Memory
• What abilities decline?
• Source judgments and encoding details
Parkin & Walter (1992)
Mean Number Recalled
70
60
50
40
Remember
Know
30
20
10
0
Young
Middle-old
Age
Older
Aging: Episodic Memory
• Autobiographical Memories, Piolino et al (2002)
• Recall of general (semantic) information from a time period: names
of people, an important date, a specific address
• Recall of episodic memory from a period: first meeting with spouse, a
day during a holiday trip
• Participants: 40s, 50s, 60s ,70s
• Semantic memories: Older
adults did equivalently with
young on information recall
• Episodic memories: More
contextual detail in event
memory, this is poorer for older
folks.
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Aging: Prospective Memory
•
Laboratory studies
• no event-based declines (cues given)
• time-based declines (self-initiated cues)
•
Unlike laboratory situations, in real-life prospective memory scenarios
the elderly often perform better than younger adults.
• Example Tasks:
• Ask participants to make a telephone call or send a postcard at a specified
time.
• Rationale:
• Older people are more aware of their memory limitations and compensate
with various strategies, such as:
• Diaries
• Reminders
• Older people live more ordered and structured lives, making it easier to form
plans.
• Older people may have been more motivated to perform well on a memory
task; younger people can explain memory slips by “being too busy”.
Aging: STM/WM
•
WM span progressively declines with age
• Park (2006)
Aging: STM/WM
•
•
WM span progressively declines with age
• But it is a very small decline
• Effects are larger when tasks involve speed of processing or
episodic, long-term memory
Type of Memory Example Test
General Findings
Verbal span
Digit span
Declines by < 1 item
Visual span
Corsi block tapping
Declines by < ½ an item
Verbal working
memory
Recalling words in
alphabetical order
Modest decline
Sentence span
Small decline
May et al. (1999)
• The WM decline may be due to a build up of proactive
interference that older adults are less able to inhibit
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Aging: Implicit Memory
• Results are mixed, due to the wide range of implicit processes
• Generally:
• When the response is obvious and performance is measured in terms of
speed improvements
• The elderly perform well
• When the response is non-obvious, novel associations must be learned
• Older adults are impaired
• This is often the case for learning about new technologies
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Aging: Implicit Memory
• Results are mixed, due to the wide range of implicit processes
• Moderately impaired with advanced age:
• Priming tasks involving response production (e.g. stem completion)
• Small/no impairment in the elderly:
• Identification tasks (e.g. lexical decision/word fragment)
• Stronger implicit effects in the elderly
• False Fame Effect:
• Participants first see unfamiliar names, are then asked to mark names that
are famous
• Previously processed, unfamiliar names are judged as more famous
• Due to impaired recollection, forcing them to rely on familiarity
• The elderly may be more susceptible to false information and leading
questions
Aging: Memory Strategies
• Strategies are deliberate activities designed to improve memory
(e.g., tie string around finger),
• Older adults don’t spontaneously use these as much as younger adults
• True for both encoding and retrieval processes
• Why?
• “Disuse view” use these strategies because of longer time away from educational
system
• Diminished attentional capacity view: Fewer attentional resources available to
engage in encoding strategies (and maybe they don’t execute them as well)
• Memory self-efficacy view: Older individuals don’t have confidence in their own
memory systems, so they expect poor memory and don’t use the strategies
• Using strategies helps remembering, but doesn’t fully account for age
differences in recall (Herzog et al., 1998)
Theories of Aging
• Why do they decline?
• “Use it or lose it” (Disuse view)
• Systems view
• Processing views
• Speed
• Lack of inhibition
• Transfer-appropriate processing
Theories of Aging
• Why do they decline?
• “Use it or lose it” (Disuse view)
• Analogy to exercise and muscle atrophy, if you aren’t using
memories (or memory systems), then functioning declines
• Not a lot of support for this view
• Many tasks that are still important for day-to-day functioning
still show age related impairments
• Problems with circularity in the data
• Older people with good memory functioning use it more,
which in turn leads to better memory functioing
Theories of Aging
• Why do they decline?
• Systems view
• Episodic memory system is last to develop and first to
decline
• Predicts across the board effects on memory systems
• But, can find variability in performance depending on task, (so
maybe it isn’t the system, but rather processes)
Theories of Aging
• Why do they decline?
• Processing views
• Speed
• Salthouse (1996) Many of the cognitive effects of aging are
caused by reduced processing speed
• Digit Symbol Substitution Test (DSST) is a good predictor of
age deficits
• Lack of inhibition
• Hasher and Zacks (1988) Inhibition Deficit Hypothesis of
Aging:
• A major cognitive effect of aging is the reduced capacity to
inhibit irrelevant stimuli
• May result in build up of proactive interference
Theories of Aging
• Why do they decline?
• Processing views
• Transfer-appropriate processing
• Age related declines are related to the availability of
appropriate/good quality cues at retrieval
• For tasks in which good cues are available, age related memory
differences typically disappear
Brief summary
• Memory: Memory changes during aging but not all in the same way
• Working memory and perceptual speed: decline during the late
adulthood years
• Episodic memory: younger adults have better episodic memory
• Source memory: the ability to remember where one learned something
• Decreases with age during late adulthood
• Semantic memory: does not decline as drastically as episodic memory
• Exception: tip-of-the-tongue phenomenon
• Implicit memory: shows less aging declines than explicit memory