Transcript Chap6d
Cognitive Processes
PSY 334
Chapter 6 – Human Memory:
Encoding and Storage
Ebbinghaus
First rigorous investigation of human
memory – 1885.
Taught himself nonsense syllables
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:
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:
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
Bright postexposure field wipes out
memory after 1 sec, dark after 5 sec.
Echoic memory – auditory
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.
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.
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.
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.
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:
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.
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.
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.
How much we have practiced the
memory – how frequently it is used.
Anderson’s study (sailor is in the park)
Spreading Activation
Activation spreads along the paths
of a propositional network.
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.
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:
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.
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:
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:
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.
64% correct, compared to 57% (controls)
76% of relevant questions correct, 52% of
non-relevant.
These study techniques work because
they encourage elaboration.
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.
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.
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.
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.
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.
Seem vivid but can be very inaccurate.
Thatcher’s resignation:
60% memory for UK subjects, 20% nonUK
Self-Reference Effect
Two explanations:
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.