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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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Memory and cognition

Memory and Cognition

PSY 324

Topic: Long-term Memory- Encoding and Retrieval

Dr. Ellen Campana

Arizona State University


Storage of memories
Storage of Memories

  • 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

    • Transferring information TO LTM is called encoding or storage

    • Vocabulary note:

      • 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
Rehearsal

  • We saw last chapter that in certain cases simply repeating information can cause it to be stored

    • What affect showed this in the last class???

  • Simply repeating information is called maintenance rehearsal because it is most useful for keeping the information in STM/WM

    • 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

    • 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
Levels of Processing Theory(Craik & Lockhart, 1972)

  • Basic idea: memory depends on the specific process used to get information into LTM

    • Shallow processing: little attention to meaning, based on surface characteristics

      • Count the vowels

    • Deep processing: considering meaning and/or relating items to other information in LTM

      • 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
Levels of Processing

  • Craik & Tulving (1975) introduced more levels

    • Shallow: A question about the physical features

      • Is the word printed in capital letters? [bird]

    • Deeper: A question about rhyming

      • Does the word rhyme with train? [pain]

    • Deepest: A fill-in-the-blanks question

      • Does the word fit in the sentence “he saw a ___ on the street”? [car]


Levels of processing1
Levels of Processing

% of words recalled after delay

Fill-in-the-blanks

Rhyme

Capital Letters


Levels of processing2
Levels of Processing

  • Are you convinced?

    • 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.

  • 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
Transfer-Appropriate Processing

  • Basic idea: memory is best when the task at encoding matches the task at retrieval

    • 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?)


Transfer appropriate processing1
Transfer-Appropriate Processing

Standard Recognition Test

Matching

Rhymed Recognition Test

% correct

Fill-in-the-blanks

Rhyme


Other factors that aid encoding
Other factors that aid encoding

  • NOTE: All of these are about encoding, but caused by increasing retrieval cues

  • Forming connections with other information

    • More vivid /detailed => better memory

    • Visually imagining pairs of words => better memory

      • Bower & Wizenz (1970)

    • Self-reference effect

      • Rogers and Coworkers (1979)


Other factors that aid encoding1
Other factors that aid encoding

  • Generating information

    • The generation effect (Slameka and Graf, 1978)

      • Read (king-crown) vs fill-ins (king-cr_____)

      • Memory for words that were filled in is better

  • Organizing information

    • Bower and colleagues –similar groupings

    • Bransford and Johnson – balloon picture study


Encoding specificity
Encoding Specificity

  • Basic idea: Context of learning (location, etc.) can act as a retrieval cue

    • It’s actually good for you that we’re using scan-tron!

  • Diver Study (who?)

    • Group of divers

      • ½ learned a list on land

      • ½ learned a list under water

      • ½ tested on land

      • ½ tested under water


State dependent learning
State-Dependent Learning

  • Basic idea: Your own internal state can act as a retrieval cue

    • Emotions, sleep-deprivation state, chemicals


How long term memories are stored

How Long-term Memories are Stored

(biologically-speaking)


Storage at the synapse
Storage at the Synapse

  • Remember Chapter 2, discussion of faces?


Storage at the synapse1
Storage at the Synapse

  • Representation of each face is a memory

    • 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

  • Hebbian Learning, Long-term Potentiation

    • “Neurons that fire together, wire together”




Storage at the synapse3
Storage at the Synapse

  • Process of Long-term Potentiation

    • A and B are connected such that A’s axon synapses with B’s dendrite

      • 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

    • Important because it is used in connectionist models


Fragility of new memories
Fragility of New Memories

  • 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)

  • Another dimension of amnesia

    • Retrograde amnesia – loss of declarative memory for events prior to a trauma

      • Graded amnesia – loss worse for more recent memories

    • Anterograde amnesia – inability to form new memories


Graded amnesia

FUTURE

PAST

Graded Amnesia

  • H.M. in your book (had hippocampus removed)

    • Had both retrograde and anterograde amnesia

    • His retrograde amnesia was graded

      • Could remember events before 10-15yrs before operation

      • More recent memories, more damage

Operation

Old memories have graded damage

New memories are

never even formed


Graded amnesia1
Graded Amnesia

  • Why talk about graded amnesia right now?

    • Demonstrates that recent memories are more fragile

      • Some process must make memories less fragile

    • Hippocampus involved in recent (not old) memories

      • That’s because H.M. had no hippocampus

  • Consolidation is the process that makes memories less fragile over time

    • Synaptic consolidation

    • Systems consolidation


Process of consolidation
Process of Consolidation

  • Synaptic consolidation

    • First type to be studied

    • Rapid, happens over the time span of minutes

    • Long-term Potentiation is an example

  • Systems consolidation

    • Large-scale reorganization of circuits of neurons

    • Gradual, happens over days, weeks, months, years

    • Standard model of consolidation

      • Retrieval depends on hippocampus during consolidation

      • Afterwards, hippocampus no longer involved


Standard model of consolidation
Standard Model of Consolidation

  • Early on, memory is distributed across the brain, no connections between active cortical areas

    • Sights, sounds, smells, etc.

  • Hippocampus coordinates activity across the cortical area during memory reactivation

    • Links form between active cortical areas

  • Gradually the hippocampus is no longer involved in retrieval



Standard model of consolidation2
Standard Model of Consolidation

  • Much of consolidation (including reactivation) happens during sleep / relaxed wakefulness

  • Can also happen during rehearsal

    • Especially elaborative rehearsal

  • Results in situation where only cortical activity is necessary for remote memories

    • Remote memories are memories for events that occurred long ago


Consolidation controversy
Consolidation Controversy

  • That’s the nice clean model… but there is controversy about the claim that the hippocampus completely drops out of retrieval

    • 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

    • Evidence for hippocampal involvement

      • Brain imaging studies looking at episodic memories



Studying for tests
Studying for Tests

  • Elaborate and Generate – why?

  • Organize – why?

  • Associate – why?

  • Take breaks – why?

    • Distributed vs. Massed Practice Effect

  • Match Learning and Testing Conditions

    • ….or at least move around a lot



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