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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