Download 1 Memory (1) Visual Sensory Store

Memory (1)
Atkinson & Shiffrin (1968) Model of Memory
Visual Sensory Store
• It appears that our visual system is able to hold a great
deal of information but that if we do not attend to this
information it will be rapidly lost.
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Demo at:
http://www.dualtask.org/
• Sperling (1960)
– Presented array consisting of three rows of four letters
– Subjects were cued to report part of display
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Visual Sensory Memory
Mean number of words reported
• Vary the delay of cue in
partial report
• After one second,
performance reached
asymptote
Delay of cue (in seconds)
Iconic Memory
• Sperling’s experiments indicate the existence of a brief
visual sensory memory – known as iconic memory or
iconic store
• Information decays rapidly unless attention is transfers
items to short-term memory
• Analogous auditory store: echoic store
Atkinson & Shiffrin (1968) Model of Memory
Short-term memory (STM) is a limited capacity store for
information -- place to rehearse new information from sensory
buffers
Items need to be rehearsed in short-term memory before
entering long-term memory (LTM)
Probability of encoding in LTM directly related to time in STM
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a memory test...
DOORKNOB
CONCRETE
SUNSHINE
SOFTBALL
RAILROAD
CURTAIN
HAMMER
SUBWAY
DOCTOR
CANDLE
TURKEY
COFFEE
FOLDER
PLAYER
LETTER
PENCIL
TOWEL
KITTEN
MAPLE
TABLE
Serial Position Effects
no
distractor
task
distractor
task
• In free recall, more items are recalled from start of list
(primacy effect) and end of the list (recency effect)
• Distractor task (e.g. counting) after last item removes recency
effect
Serial Position Effects
• Explanation from Atkinson and Shiffrin (1968) model:
– Early items can be rehearsed more often
Æ more likely to be transferred to long-term memory
– Last items of list are still in short-term memory (with no
distractor task)
Æ they can be read out easily from short-term memory
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Forgetting over time in short-term memory.
Peterson and Peterson (1959)
Baddeley’s working memory system.
Baddeley proposed replacing unitary short-term store
with working memory model with multiple components:
• Phonological loop
• Visuo-spatial sketchpad
• Central executive (ignore the episodic buffer)
Baddeley and Hitch (1974)
Baddeley (1986)
Phonological Loop
(a.k.a. articulatory loop)
• Stores a limited number of sounds – number of words is
limited by pronunciation time, not number of items
• Experiment:
LIST 1:
Burma
Greece
Tibet
Iceland
Malta
Laos
LIST 2:
Switzerland
Nicaragua
Afghanistan
Venezuela
Philippines
Madagascar
• Word length effect – mean number of words recalled in
order (list 1 Æ 4.2 words; list 2 Æ 2.8 words)
• Phonological loop stores 1.5 - 2 seconds worth of words
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Two routes to phonological loop
Visual
presentation
Articulatory
control
process
Speech code
Auditory
presentation
Phonological
loop
• Articulatory control process converts visually presented
words into a speech code
• Articulatory suppression (e.g. saying “the” all the time)
disrupts phonological loop
• Prediction:
– Word length effect depends on phonological loop
– With articulatory suppression, visually
presented items should not display word length effect
Immediate word recall as a function of modality of presentation
(visual vs. auditory), presence vs. absence of articulatory
suppression, and word length.
Baddeley et al. (1975).
Working memory and Language Differences
• Different languages have
different #syllables per
digit
• Therefore, recall for
numbers should be
different across
languages
• E.g. memory for English
number sequences is
better than Spanish or
Arabic sequences
(Naveh-Benjamin & Ayres, 1986)
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Evaluation of the Evidence for the
Phonological Loop
• Accounts for phonological similarity and the word-length
effect
• Support from neuroimaging studies
• Baddeley, Gathercole, and Papagno (1998)
– Its function may be to learn new words
Encoding & Retrieval Effects
Levels of Processing
(Craik & Lockhart, 1972)
Levels of processing effect:
Deeper levels of processing (e.g., emphasizing meaning)
leads to better recall.
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Encoding Specificity Principle
• Recollection performance depends upon the interaction
between the properties of the encoded event and the
properties of the retrieval information
Context Change
• Information learned in a particular context is better
recalled if recall takes place in the same context
• Similarly, information learned in a particular context may
be difficult to recall in a dramatically different context
Godden & Baddeley (1975, 1980)
Memory experiment with deep-sea divers
– Deep-sea divers learned words either on land or underwater
– They then performed a recall or recognition test on land or
underwater
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Mood-dependent Memory
• Easier to remember happy memories in a happy state
and sad memories in a sad state.
• Subjects study positive or negative words in normal state.
Test in positive or negative induced states.
Æ mood primes certain memory contents
Kenealy (1997).
State-dependent recall
• Does physical state matter?
• Eich et al. (1975): study while smoking normal or
marijuana cigarette. Test words under same or different
physical condition
Forgetting
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Forgetting Functions
• Ebbinghaus (1885/1913): Forgetting over time as
indexed by reduced savings.
Most forgetting
functions show:
Negative acceleration
Rate of change gets
smaller and smaller
with delay
Power law of
forgetting
Forgetting
Why do we forget?
Some possibilities:
• Memory has disappeared
Æ decay theory
• Memory is still there but we can’t retrieve it
Æ repression
Æ inhibition theory
Æ interference theory
What is Repression?
• “Something happens that is so shocking that the mind
grabs hold of the memory and pushes it underground,
into some inaccessible corner of the unconscious.”
- Loftus (1993)
• Some self-help book (“Courage to Heal”) relate
repressed memories to sexual abuse
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Recovered memory vs. False Memory
• How do we know whether repressed memories are
accurate?
• In some cases, traumatic information is misremembered
or simply “made up”
– Loftus has been involved in many cases
– Points out problems of
• hypnosis
• suggestive questioning
• dream interpretations
Elizabeth Loftus
False Memory in the Lab
• Deese, Roediger, McDermott paradigm
• Study the following words
SLUMBER
BLANKET
DROWSY
SNOOZE
DREAM
AWAKE
SNORE
PEACE
TIRED
YAWN
WAKE
DOZE
REST
BED
NAP
• Recall test ....
• Recognition memory test
Use ratings 1) sure new 2) probably new 3) probably old
4) sure old
• TEST:
COFFEE
SNORE
SLEEP
REST
Results
• Critical lure (“sleep”) are words not presented but similar
to studied words. These words are often falsely recalled
(sleep: 61% of Ss.)
• Recognition memory results
proportion of items classified with confidence levels:
confidence rating
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3
2
1
studied items
not studied
unrelated
critical lure
.75
.11
.09
.05
(e.g. “REST”)
.00
.58
.02
.26
.18
.08
.80
.08
(e.g. “COFFEE”)
(e.g. “SLEEP”)
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Subjects reporting recovered memories are
more vulnerable to false memories
False recognition
of words not
presented in four
groups of women
with lists containing
eight associates.
Clancy et al. (2000)
Proactive and retroactive interference
Inhibitory mechanisms in Forgetting
• Cued recall as a
function of the
number of times the
cues had been
presented before for
recall (respond
condition) or for
suppression
(suppress condition).
Anderson and Green (2001)
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