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Chapter 7
Long-Term Memory: Encoding, Retrieval, and Consolidation
Some Questions to Consider
- What is the best way to store information in long-term memory?
- What are some techniques we can use to help us get information out of long-term memory when we need it?
- How is it possible that a lifetime of experiences and accumulated knowledge can be stored in neurons?
- How can the results of memory research be used to create more effective study techniques?
Getting Information Into LTM
- Encoding
- acquiring information and transforming it into memory
- Retrieval
- transferring information from LTM to working memory
- Maintenance rehearsal
- repetition of stimuli that maintains information but does not transfer it to LTM
- Elaborative rehearsal
- using meanings and connections to help transfers information to LTM
Levels of Processing Theory
- Memory depends on how information is encoded
- Depth of processing
- Shallow processing
- little attention is devoted to meaning
- the focus is on the physical features on the information
- memory for information processed this way is poor
- Deep processing
- close attention is devoted to meaning
- memory for information processed this way is better
Levels of Processing Theory
- Craik and Tulving (1975) study
- In some trials participants are asked if a word has or does not have capital letter.
- They see “Bird”; answer is yes it has a capital letter
- This would be shallow processing
- In other trials participants are asked if a word rhymes with another word.
- They see “pain” and then “train”; answer is yes, they rhyme
- This would be deeper processing.
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Other Factors that Aid Encoding
- Visual imagery
- Asking participants to imagine a picture of two words interacting as opposed to asking them to memory two words improves by more than two times.
- 5% recall to 13% recall
Other Factors that Aid Encoding
- Self-reference effect
- the tendency for people to have better recall or recognition when the memorized information is relevant to them
- Rathbone and Moulin (2010)
- Participants generated friends' birthdays from memory and then gave their own birthday.
- Participants were particularly likely to recall birthdays from on or around the date of their own birthday.
- Thus, memory for birthdays clusters around self-relevant information
Other Factors that Aid Encoding
- Generation effect
- a robust memory phenomenon in which actively producing material during encoding acts to improve later memory performance.
- Rosner, Elman and Shimamura (2013) explored the neural basis of this effect in an fMRI analysis.
- During encoding, participants generated synonyms from word-fragment cues (e.g. GARBAGE-W_ST_) or read other synonym pairs (e.g. GARBAGE-WASTE).
- Compared to simply reading target words, generating target words significantly improved later recognition memory performance.
- During encoding, this benefit was associated with both the prefrontal and posterior cortex
Other Factors that Aid Encoding
- Organizing to-be-remembered information
- Separating items to be remembered into categories
- Color coding words to be remembered
- Relating words to survival value
- When participants are asked to rate a list of words according to survival value (what they might need if stranded on a desert island), they were better remembered than if they just tried to memorize the words.
Organization, Comprehension,
and Memory
- Bransford & Johnson (1972)
- Presented participants with difficult-to-comprehend information
- Group 1 first saw a picture that helped explain the information
- Group 2 saw the picture after reading the passage
- Control Group did not see the picture
- Group 1 outperformed the others.
- Having a mental framework of comprehension aided memory encoding and retrieval
Organization, Comprehension,
and Memory
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Retrieval Practice
- Which results in a stronger memory trace?
- Re-reading the material
- Being tested on the material
- Roediger and Karpicke (2006) had participants read a passage and then either
- Reread the passage (rereading group)
- Take a recall test (testing group)
- Then tested recall after a delay; testing group performed better
- Testing Effect
- Practice quizzes are often helpful and incorporated into textbooks to improve test performance.
Retrieval Practice
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Retrieving Information from LTM
- Retrieval
- process of transferring information from LTM back into working memory (consciousness)
- Most of our failures of memory are failures to retrieve
Retrieving Information from LTM
- Cued-recall: cue presented to aid recall
- Increased performance over free-recall
- Retrieval cues most effective when created by the person who uses them
- https://www.khanacademy.org/science/health-and-medicine/executive%20systems%20of%20the%20brain/memory-2014-03-27T18:40:29.837Z/v/retrieval-free-recall-cued-recall-and-recognition
Encoding Specificity
- We learn information together with its context
- Baddeley’s (1975) “diving experiment”
- Best recall occurred when encoding and retrieval occurred in the same location
- This means that the best place for you to study for a test is in the same room where you are going to take the test.
- In an online class you should try to do all work and tests in the same place even though you could take your laptop or tablet anywhere.
Encoding Specificity
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State-Dependent Learning
- Learning is associated with a particular internal state
A Negative Mood Always
Impairs Memory
State Dependent Learning
- When in a negative mood, we remember negative info better.
- When in a positive mood, we remember positive info better.
Improving Learning and Memory
- Distributed vs. massed practice effect
- It is difficult to maintain close attention throughout a long study session.
- Cramming all night or for long hours before a test is not good.
- Studying after a break gives feedback about what you already know.
- Studying should be distributed over several sessions.
Matching the Cognitive Task
- Transfer-appropriate processing
- the results of a memory task will be better if the type of processing used during encoding is the same as the type during retrieval
- Morris et al. (1977)
Consolidation in the Brain
- Transforms new memories from a fragile state that is easily lost to more permanent state
- Synaptic consolidation
- occurs at synapses and happens rapidly over minutes or hours
- Systems consolidation
- involves gradual reorganization of circuits in brain
- Takes place over months or years
- Muller and Pilzecker (1900)
- Two groups of people learned nonsense syllables (TEP)
- Immediate group learned one list and then immediately learned a second list; had 28% recall
- Delay group learned first list and then, after a 6 min delay, learned the second list; had 48% recall
- Studying new list immediately interrupted the consolidation of the first list; participants couldn’t get the second list into a permanent state.
Consolidation
Information Storage at the Synapse
- Hebb (1948)
- Learning and memory represented in the brain by physiological changes at the synapse
- Neural record of experience
- Learning produces changes in:
- EEG activity
- Firing pattern of cells is altered
- RNA and protein synthesis
- Increase in number of synapses increase
- Excitability of cell membranes (STM)
- number of connections between neurons (LTM)
- Number of branches between neurons increases
Information Storage at the Synapse
- Long-term potentiation (LTP)
- Enhanced firing of neurons after repeated stimulation
- There are both structural changes and enhanced responding
Information Storage at the Synapse
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Consolidation
- Standard model of consolidation
- Retrieval depends on hippocampus during consolidation; after consolidation hippocampus is no longer needed
- Reactivation: hippocampus replays neural activity associated with memory
The Fragility of New Memories
- Retrograde amnesia
- loss of memory for events prior to the trauma
- Graded amnesia
- memory for recent events is more fragile than for remote events
- There hasn’t been enough time for consolidation.
Consolidation
- Multiple trace hypothesis
- Questions the assumption that the hippocampus is important only at the beginning of consolidation
- The hippocampus has been shown to be activated during retrieval of both recent and remote memories (Gilboa et al., 2004)
- The response of the hippocampus can change over time (Viskontas and coworkers, 2009)
Are Memories Ever “Permanent”?
- Reactivation and reconsolidation evidence from research on animals
- Occurs under certain conditions
- Human memory is a “work in progress”
- Scientists can learn a lot from people who seem to have superior unlimited memory.
- https://www.youtube.com/watch?v=2zTkBgHNsWM
- https://www.youtube.com/watch?v=1th1fVIc8Vo
Improving Learning and Memory
- Elaborate
- associate what you are learning to what you already know
- Generate and test
- The generation effect
- Take breaks
- Memory is better for multiple short study sessions (the spacing effect)
- Consolidation is enhanced if you sleep after studying (in other words, no all nighters!)
- Avoid the “illusion of learning”
- Familiarity does not mean comprehension