Transcript Jul31

Cognitive Processes
PSY 334
Chapter 6 – Human Memory:
Encoding and Storage
July 31, 2003
Depth of Processing
 Craik & Lockhart – proposed that it is not
how long material is rehearsed but the
depth of processing that matters.
 Levels of processing demo.
Working Memory
 Baddeley – in working memory speed of
rehearsal determines memory span.
Articulatory loop – stores whatever can
be processed in a given amount of time.
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Word length effect: 4.5 one-syllable words
remembered compared to 2.6 long ones.
1.5 to 2 seconds material can be kept.
Visuospatial sketchpad – rehearses
images.
Central executive – controls other systems.
Delayed Matching Task
 Delayed Matching to Sample – monkey
must recall where food was placed.
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Monkeys with lesion to frontal cortex
cannot remember food location.
Human infants can’t do it until 1 year old.
 Regions of frontal cortex fire only during
the delay – keeping location in mind.
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Different prefrontal regions are used to
remember different kinds of information.
Activation
 Activation – how available
information is to memory:
Probability of access – how likely you
are to remember something.
 Rate of access – how fast something
can be remembered.
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 From moment to moment, items
differ in their degree of activation in
memory.
Factors Affecting Activation
 How recently we have used the
memory:
Loftus – manipulated amount of delay
 1.53 sec first time, then 1.21, 1.28,
and 1.33 with 3 items intervening.
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 How much we have practiced the
memory – how frequently it is used.
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Anderson’s study (sailor is in the park)
Spreading Activation
 Activation spreads along the paths
of a propositional network:
Dog – c
 Bone – m
 1.41 sec
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Gambler – c
bone – m
1.53 sec
 Associative priming – involuntary
spread of activation to associated
items in memory.
Associative Priming
 Meyer & Schvaneveldt – spreading
activation affects how fast words
are read.
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Subjects judged whether pairs of
related & unrelated items were words.
 Ratcliff & McKoon – priming
influences word recognition.
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Subjects identified words from
sentences faster with priming.
Practice and Strength
 Amount of spreading activation
depends on the strength of a
memory.
 Memory strength increases with
practice.
 Greater memory strength increases
the likelihood of recall.
Power Function
 Each time we use a memory trace,
it gradually becomes a little
stronger.
 Power law of learning:
T = 1.40 P-0.24
 T is recognition time, P is days of
practice.
 Linear when plotted on log-log scale.
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Long Term Potentiation (LTP)
 Neural changes may occur with
practice:
Long-term potentiation (LTP) in
hippocampus.
 Repeated electrical stimulation of
neurons leads to increased
sensitivity.
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 LTP changes are a power function.
Factors Influencing Memory
 Study alone does not improve memory –
what matters is how studying is done.
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Shallow study results in little improvement.
Semantic associates (tulip-flower) better
remembered than rhymes (tower-flower),
81% vs 70%.
 Better retention occurs for more
meaningful elaboration.
Elaborative Processing
 Elaboration – embellishing an item with
additional information.
 Anderson & Bower – subjects added
details to simple sentences:
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57% recall without elaboration
72% recall with made-up details added
 Self-generated elaborations are better
than experimenter-generated ones.
Self-Generated Elaborations
 Stein & Bransford – subjects were given
10 sentences. Four conditions:
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Just the sentences alone – 4.2 adjectives
Subject generates an elaboration – 5.8
Experimenter-generated imprecise
elaboration – 2.2
Experimenter-generated precise
elaboration – 7.8
 Precision of detail (constraint) matters,
not who generates the elaboration.
Advance Organizers
 PQ4R method – use questions to guide
reading.
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64% correct, compared to 57% (controls)
76% of relevant questions correct, 52% of
non-relevant.
 These study techniques work because
they encourage elaboration.
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Question making and question answering
both improve memory for text (reviewing is
better than seeing the questions first).
Meaningful Elaboration
 Elaboration need not be meaningful –
other sorts of elaboration also work.
 Kolers compared memory for right-sideup sentences with upside-down.
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Extra processing needed to read upside
down may enhance memory.
 Slamecka & Graf – compared generation
of synonyms and rhymes. Both improved
memory, but synonyms did more.
Incidental Learning
 It does not matter whether people intend
to learn something or not.
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What matters is how material is processed.
 Orienting tasks:
 Count whether work has e or g.
 Rate the pleasantness of words.
 Half of subjects told they would be asked
to remember words later, half not told.
 No advantage to knowing ahead of time.
Flashbulb Memories
 Self-reference effect -- people have
better memory for events that are
important to them and close friends.
 Flashbulb memories – recall of traumatic
events long after the fact.
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Seem vivid but can be very inaccurate.
 Thatcher’s resignation:
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60% memory for UK subjects, 20% nonUK
Neural Correlates of Encoding
 Better memory occurs for items with
stronger brain processing at the time of
study:
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Words evoking higher ERP signals are
better remembered later.
Greater frontal activation with deeper
processing of verbal information.
Greater activation of hippocampus with
better long-term memory.