Download Cognitive Processes PSY 334

Cognitive Processes
PSY 334
Chapter 6 – Human Memory:
Encoding and Storage
Ebbinghaus
† First rigorous investigation of human
memory – 1885.
† Taught himself nonsense syllables
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DAX, BUP, LOC
† Savings – the amount of time needed to
relearn a list after it has already been
learned and forgotten.
† Forgetting function – most forgetting
takes place right away.
Memory Models
† Atkinson & Shiffrin – proposed a three-
stage model including:
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Sensory store – if attended goes to STM
Short-term memory (STM) – if rehearsed
goes to LTM
Long-term memory (LTM)
† No longer the current view of memory.
„
Still presented in some books.
The Three-Stage Model
Responses
Sensation/perception
Environment
Attention
Sensory store
retrieval
Short-term
(working) memory
Long-term memory
encoding
Executive control processes
Retention Times
retrieval
Environment
Sensory store
Short-term
(working) memory
Long-term memory
encoding
1-3 seconds
15-25 seconds
1 sec to a lifetime
Sensory Memory
† Holds info when it first comes in.
† Allows a person to extract meaning from
an image or series of sounds.
† Sperling’s partial report procedure:
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A display of three rows of letters is
presented.
After it is taken away, a tone signals which
row to report.
Subjects were able to report most letters.
Sperling’s Partial Report
A medium tone
signals the subject
to report the letters
in this row
Sperling’s Results
Delay
Kinds of Sensory Stores
† Iconic memory – visual
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Bright postexposure field wipes out
memory after 1 sec, dark after 5 sec.
† Echoic memory – auditory
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Lasts up to 10 sec (measured by ERP)
† Located in the sensory cortexes.
Short Term Memory
† The original idea is that when info in
sensory memory is paid attention to, it
moves into short term memory.
† With rehearsal, it then moves into long
term memory.
† STM has limited capacity, called memory
span.
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Miller’s magic number (7 ± 2)
New info pushes out older info (Shepard)
Shepard’s Results
Probability of recalling
the target item
Number of
intervening items
Criticisms of STM
† Rate of forgetting seemed to be quicker
than Ebbinghaus’s data, but is not really.
† Amount of rehearsal appeared to be
related to transfer to long-term memory.
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Later it was found that the kind of
rehearsal matters, not the amount.
Passive rehearsal does little to achieve
long-term memory.
† Information may go directly to LTM.
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.
Visuopatial sketchpad – rehearses images.
Central executive – controls other systems.
Word-Lenth Determines
Forgetting
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.
„
Different prefrontal regions are used to
remember different kinds of information.
Delayed Matching to Sample
Importance of Frontal Cortex
† In primates, working memory is localized
to the frontal cortex.
† Delayed matching to sample task:
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Monkeys are shown food that is then
hidden.
Later they are given a chance to locate it.
† Monkeys with frontal lobe lesions cannot
do this task.
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.
„
† From moment to moment, items
differ in their degree of activation in
memory.
Anderson’s ACT Model
† ACT – Adaptive Control of Thought
† Moses Effect -- subjects shown the
words Bible, animal and flood should
recall Noah but recall Moses instead.
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When given the word flood they think of
Mississippi or Johnstown but not Noah.
† Why? Recall is based on both baseline
and activation from associated concepts.
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Moses and Jesus have higher baselines.
The ACT Model
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.
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Related items are faster to recall.
† Associative priming – involuntary
spread of activation to associated
items in memory.
„
Kaplan’s dissertation – cues to
solving riddles hidden in the
environment led to faster solutions.
Associative Priming
† Meyer & Schvaneveldt – spreading
activation affects how quickly words
are read.
Subjects judged whether pairs of
related & unrelated items were words.
„ Judgments about related words were
faster.
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Meyer and Schvaneveldt
Practice and Strength
† The 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.
„
Learning Curves
Practicing Addition Problems
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.
„
† LTP changes are a power function.
Neural Changes Mirror
Behavioral Changes
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.
Activation in Prefrontal Cortex
Words activate left
prefrontal cortex
Pictures activate right
prefrontal cortex
Hemodynamic =
blow flow during
brain activity
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.
Slamecka & Graf’s Results
Mnemonics
† Method of Loci – place items in a
location, then take a mental walk.
† Peg-word System – use peg words as a
structure and associate a list of items
with them using visualization.
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Create acronyms for lists of items.
† Convert nonsense syllables (DAX, GIB)
into meaningful items by associating
them with real words (e.g., DAD).
“This Old Man” Song
† http://www.youtube.com/watch?v=3cYf9vkW_xU
† http://www.totlol.com/watch/5d-6Q5V79CM/This-Old-Man/0/
Pegword System
1 – bun
2 – shoe
3 – tree
4 – door
5 – hive
6 – sticks
7 – heaven
8 – gate
9 – wine
10 -- hen
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:
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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.
Awareness of Learning
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
Self-Reference Effect
† Two explanations:
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People have special mechanisms for
encoding info relevant to themselves.
Info relevant to the self is rehearsed more
often.
† High arousal may enhance memory.
† Memory is better for words related to the
self – perhaps due to better elaboration.