Transcript Memory_Ch7_all - Arizona State University

Memory and Cognition
PSY 324
Topic: Long-term Memory- Encoding and Retrieval
Dr. Ellen Campana
Arizona State University
Storage of Memories
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Information is used in one type of memory system
(STM / WM) but in order for it to stick around for
longer than a few seconds it needs to be transferred
into Long-term Memory
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Transferring information TO LTM is called encoding or
storage
Vocabulary note:
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Coding refers to the form in which information is represented
Encoding refers to the process used to get information into LTM
Transferring information OUT OF LTM in order to use it in
STM/WM is called retrieval
Rehearsal
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We saw last chapter that in certain cases simply repeating
information can cause it to be stored
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Simply repeating information is called maintenance rehearsal
because it is most useful for keeping the information in
STM/WM
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Maintenance rehearsal is actually NOT an effective way to transfer
information to LTM
A more effective way to encode information is through
elaborative rehearsal – making connections between the new
item and memories you already have
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What affect showed this in the last class???
Does this sound familiar? What concept is like this in STM?
Levels of Processing Theory explains these differences
Levels of Processing Theory
(Craik & Lockhart, 1972)
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Basic idea: memory depends on the specific process
used to get information into LTM
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Shallow processing: little attention to meaning, based on
surface characteristics
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Deep processing: considering meaning and/or relating
items to other information in LTM
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Count the vowels
Think about how useful it would be on a desert island
Try the demo on page 198 (takes too long for class)
Confirmed in many different studies of memory for
words, but two levels turned out to be too simple
Levels of Processing
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Craik & Tulving (1975) introduced more levels
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Shallow: A question about the physical features
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Deeper: A question about rhyming
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Is the word printed in capital letters? [bird]
Does the word rhyme with train? [pain]
Deepest: A fill-in-the-blanks question
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Does the word fit in the sentence “he saw a ___ on the
street”? [car]
Levels of Processing
% of words
recalled after
delay
Fill-in- Rhyme
theblanks
Capital
Letters
Levels of Processing
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Are you convinced?
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People were, at first. But then a bunch of new tasks
were tried and a people discovered a circularity in
the argument
What makes a level “deep”? It leads to better memory.
 And why care about “depth”? It can predict memory.
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Dissatisfaction with the Levels of Processing
Theory coincided with introduction of a new
theory about the encoding of long-term
memory: Transfer-Appropriate Processing
Transfer-Appropriate Processing
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Basic idea: memory is best when the task at
encoding matches the task at retrieval
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Morris and Coworkers (1977) independently varied
the tasks at encoding and retrieval
Encoding tasks: meaning-task (fill-in-the-blanks) and
rhyming-task
 Retreival tasks: standard recognition task and rhymed recognition
task (does it rhyme with a word you heard?)
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Transfer-Appropriate Processing
Matching
Standard
Recognition Test
Rhymed
Recognition Test
% correct
Fill-intheblanks
Rhyme
Other factors that aid encoding
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NOTE: All of these are about encoding, but
caused by increasing retrieval cues
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Forming connections with other information
More vivid /detailed => better memory
 Visually imagining pairs of words => better memory
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Bower & Wizenz (1970)
Self-reference effect
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Rogers and Coworkers (1979)
Other factors that aid encoding
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Generating information
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The generation effect (Slameka and Graf, 1978)
Read (king-crown) vs fill-ins (king-cr_____)
 Memory for words that were filled in is better
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Organizing information
Bower and colleagues –similar groupings
 Bransford and Johnson – balloon picture study
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Encoding Specificity
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Basic idea: Context of learning (location, etc.) can act
as a retrieval cue
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It’s actually good for you that we’re using scan-tron!
Diver Study (who?)
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Group of divers
½ learned a list on land
 ½ learned a list under water
 ½ tested on land
 ½ tested under water
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State-Dependent Learning
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Basic idea: Your own internal state can act as a
retrieval cue
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Emotions, sleep-deprivation state, chemicals
How Long-term
Memories are Stored
(biologically-speaking)
Storage at the Synapse
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Remember Chapter 2, discussion of faces?
Storage at the Synapse
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Representation of each face is a memory
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How did these particular memories come to be
represented by these particular neurons firing in this
pattern?
Key is in the synapses between neurons
Neurotransmitters cause structural changes
 Structural changes modify the firing rate of neurons
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Hebbian Learning, Long-term Potentiation
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“Neurons that fire together, wire together”
Structure of a Neuron
Storage at the Synapse
Storage at the Synapse
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Process of Long-term Potentiation
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A and B are connected such that A’s axon synapses with B’s
dendrite
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Both A and B may be connected to many other neurons
When A and B fire at the same time, neurotransmitters cause
structural changes
Effect is that over time the same stimulus will produce faster
firing rates by B
Hebb came up with this in 1948, but neurological
evidence came much later
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Important because it is used in connectionist models
Fragility of New Memories
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Much evidence that new memories are fragile
Concussions – memory for events just prior is lost
 Electroconvulsive Therapy – again, memory for events
just prior is lost (at least temporarily)
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Another dimension of amnesia
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Retrograde amnesia – loss of declarative memory
for events prior to a trauma
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Graded amnesia – loss worse for more recent memories
Anterograde amnesia – inability to form new
memories
Graded Amnesia
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H.M. in your book (had hippocampus removed)
Had both retrograde and anterograde amnesia
 His retrograde amnesia was graded
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Could remember events before 10-15yrs before operation
 More recent memories, more damage
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FUTURE
PAST
Old memories have
graded damage
Operation
New memories are
never even formed
Graded Amnesia
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Why talk about graded amnesia right now?
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Demonstrates that recent memories are more fragile
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Hippocampus involved in recent (not old) memories
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Some process must make memories less fragile
That’s because H.M. had no hippocampus
Consolidation is the process that makes
memories less fragile over time
Synaptic consolidation
 Systems consolidation
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Process of Consolidation
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Synaptic consolidation
First type to be studied
 Rapid, happens over the time span of minutes
 Long-term Potentiation is an example
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Systems consolidation
Large-scale reorganization of circuits of neurons
 Gradual, happens over days, weeks, months, years
 Standard model of consolidation
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Retrieval depends on hippocampus during consolidation
 Afterwards, hippocampus no longer involved
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Standard Model of Consolidation
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Early on, memory is distributed across the brain,
no connections between active cortical areas
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Hippocampus coordinates activity across the
cortical area during memory reactivation
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Sights, sounds, smells, etc.
Links form between active cortical areas
Gradually the hippocampus is no longer
involved in retrieval
Standard Model of Consolidation
Standard Model of Consolidation
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Much of consolidation (including reactivation)
happens during sleep / relaxed wakefulness
Can also happen during rehearsal
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Especially elaborative rehearsal
Results in situation where only cortical activity is
necessary for remote memories
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Remote memories are memories for events that
occurred long ago
Consolidation Controversy
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That’s the nice clean model… but there is
controversy about the claim that the
hippocampus completely drops out of retrieval
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Evidence for no hippocampal involvement
Brain imaging – Medial Temporal Lobe (which contains
the hippocampus) is not active for remote memories
 Used semantic, not episodic, memories
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Evidence for hippocampal involvement
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Brain imaging studies looking at episodic memories
Test Reminders
Studying for Tests
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Elaborate and Generate – why?
Organize – why?
Associate – why?
Take breaks – why?
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Distributed vs. Massed Practice Effect
Match Learning and Testing Conditions
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….or at least move around a lot
The End