Memory and Cognition

1. Memory and Cognition PSY 324 Topic: Long-term Memory- Encoding and Retrieval Dr. Ellen Campana Arizona State University

2. 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

3. 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

4. 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

5. 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]

6. Levels of Processing % of words recalled after delay Fill-in-the-blanks Rhyme Capital Letters

7. 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

8. 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?)

9. Transfer-Appropriate Processing Standard Recognition Test Matching Rhymed Recognition Test % correct Fill-in-the-blanks Rhyme

10. 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)

11. 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

12. 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

13. State-Dependent Learning • Basic idea: Your own internal state can act as a retrieval cue • Emotions, sleep-deprivation state, chemicals

14. How Long-term Memories are Stored (biologically-speaking)

15. Storage at the Synapse • Remember Chapter 2, discussion of faces?

16. 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”

17. Structure of a Neuron

18. Storage at the Synapse

19. 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

20. 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

21. 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

22. 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

23. 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

24. 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

25. Standard Model of Consolidation

26. 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

27. 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

28. Test Reminders

29. 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

30. The End