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Chapter 7 Long-Term Memory: Encoding and Retrieval.

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1 Chapter 7 Long-Term Memory: Encoding and Retrieval

2 Some Questions to Consider What is the best way to store information in long-term memory? What are some techniques to help us get information out of LTM when we need it? How can the results of memory research be used to create more effective study techniques? How is it possible that a lifetime of experiences and accumulated knowledge can be stored in neurons?

3 Storing Information in LTM Encoding: acquiring information and transforming it into memory Maintenance rehearsal –Maintains information but does not transfer it to LTM Elaborative rehearsal –Transfers information to LTM

4 Levels of Processing Theory Memory depends on how information is encoded Depth of processing –Shallow processing: little attention to meaning (poor memory) –Deep processing: close attention to meaning (good memory)

5 Caption: (a) Sequence of events in Craik and Tulving’s (1975) experiment. (b) Results of this experiment. Deeper processing (fill- in-the-blanks question) is associated with better memory.

6 Beware of Circular Reasoning! Which task causes deeper processing? –Using a word in a sentence –Deciding how useful an object might be on a desert island Can empirically measure the memory trace in each condition –Conclude that stronger memory trace must have been caused by deeper processing But depth of processing has not been defined independently of memory performance –Therefore, this is circular reasoning

7 Caption: The circularity of defining depth of processing in terms of memory and then predicting that deeper processing will result in better memory.

8 Other Factors that Aid Encoding Imagery Creating connections, cues for remembering Self-reference effect Generation effect Organizing to-be-remembered information Testing

9 Organization, Comprehension, and Memory Bransford & Johnson (1972) Presented participants with difficult-to- comprehend information –Experimental Group 1 first saw a picture that helped explain the information –Experimental 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

10 Caption: Picture used by Bransford and Johnson (1972) to illustrate the effect of organization on memory.

11 Testing Effect 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 –Recall as much as they could –Reread the passage Tested recall after a delay

12 Caption: Results of the Roediger and Karpicke (2006) experiment. Note that at longer times after learning, the performance of the testing group is better than the performance of the rereading group.

13 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

14 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

15 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

16 Caption: (a) Design for Godden and Baddeley’s (1975) “diving” experiment. (b) Results for each test condition are indicated by the bar directly under that condition. Asterisks indicate situations in which study and test conditions matched.

17 Caption: (a) Design for Grant et al.’s (1998) “studying” experiment. (b) Results of the experiment. Asterisks indicate situations in which study and test conditions matched.

18 State-Dependent Learning Learning is associated with a particular internal state –Better memory if person’s mood at encoding matches mood during retrieval

19 Caption: (a) Design for Eich and Metcalfe’s (1989) “mood” experiment. (b) Results of the experiment.

20 Improving Learning and Memory Elaborate –Highlighting is not enough! Generate and test Organize –Helps reduce load on memory Match learning and testing conditions

21 Improving Learning and Memory Associate what you are learning to what you already know Avoid the “illusion of learning” –Familiarity does not mean comprehension Take breaks –Memory is better for multiple short study sessions –Consolidation

22 Improving Learning and Memory Distributed versus massed practice effect –Difficult to maintain close attention throughout a long study session –Studying after a break gives feedback about what you already know

23 Information Storage at the Synapse Hebb (1948) –Learning and memory represented in the brain by physiological changes at the synapse –Neural record of experience

24 Information Storage at the Synapse Long-term potentiation (LTP) –Enhanced firing of neurons after repeated stimulation –Structural changes and enhanced responding

25 Caption: What happens at a synapse as (a) a stimulus is first presented. The record next to the electrode indicates the rate of firing in the axon of neuron B. (b) As the stimulus is repeated structural changes are beginning to occur. (c) After many repetitions, more complex connections have developed between the two neurons, which causes an increase in the firing rate, even though the stimulus is the same on that was presented in (a).

26 Where Does Memory Occur in the Brain? Medial temporal lobe –Hippocampus –Perirhinal cortex

27 Caption: (a) Side view of the brain and (b) underside of the brain, showing the amygdala and structures in the medial temporal lobe (perirhinal cortex, parahippocampal cortex, entorhinal cortex, and hippocampus).

28 The Fragility of New Memories Retrograde amnesia: loss of memory for events prior to the trauma Anterograde amnesia: cannot form new memories Memory for recent events is more fragile than for remote events

29 Consolidation Transforms new memories from fragile state to more permanent state –Synaptic consolidation occurs at synapses, happens rapidly –Systems consolidation involves gradual reorganization of circuits in brain

30 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 Controversial

31 Caption: (a) According to the standard model of consolidation, retrieval of recent memories depends on the hippocampus; cortical connections have not yet formed. Thus, for retrieval of recent memories, hippocampal activation is high and cortical activation is low. (b) Once consolidation has occurred, cortical connections have formed, and the hippocampus is no longer needed. Thus, for retrieval of remote memories, cortical activation is high, and there is no hippocampal activation.

32 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)

33 Are Memories Ever “Permanent”? Reactivation and reconsolidation evidence from research on animals –Occurs under certain conditions Human memory is a “work in progress”

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