Long-Term Memory: Overview

Transcription

1 Long-Term Memory: Overview Lesson V: Long-Term Memory module 23 Long-term Memory.23. 1

2 What are we going to talk about? The structure of long-term memory Taxonomy of content Semantic coding Serial position effect Memory consolidation How are memories formed Transfer of information from STM to LTM How can we probe long-term memory? Explicit memory tests Implicit memory tests Long-term Memory.23. 2

3 What are we going to talk about? Constructive nature of memory Associations in memory Large units of knowledge (Schemata) Memory distortions Modality of long-term memory Sensory modalities and long-term memory Dual code theory: Propositional vs. imaginal codes Context effects in memory Awareness of our memories Memory strategies / Mnemonics Meta-cognitive knowledge Long-term Memory.23. 3

4 What are we going to talk about? Specific memories Autobiographical memory Mnemonists Eye-witness testimony Flashbulb memories Neuroscience of long-term memory The role of different brain centers for the formation and storage of human memories What kind of neural processes are the basis for memories Long-term Memory.23. 4

5 What do we remember? A taxonomy of LTM content Declarative memory Things we remember and can talk about Semantic memory: factual knowledge Episodic memory: memories of personal experience Non-declarative memory Procedural memory: How to do things (motor skills, perceptual learning) Associations (priming, conditioning) Long-term Memory.23. 5

6 The serial position curve Primacy Recency Long-term Memory.23. 6

7 The serial position effect: interpretation Primacy effect Less influenced by proactive interference First items are consolidated into LTM Recency effect Less influenced by retroactive interference Items still in WM / STM Modifications of the shape of the curve Delays in recall will reduce recency effect Fast presentation rate might interfere with consolidation and reduce primacy effect Amnestics might show selective impairment of primacy effect Long-term Memory.23. 7

8 A little demonstration Take 3 minutes and Write down the names of all the animals you know Time yourself and stick to three minutes Make a mark every 30 seconds so you know how far you have gotten for each half minute Long-term Memory.23. 8

9 What is stored in LTM? The role of semantic code Multimodal storage LTM by definition stores information in many specialized forms, e.g., visual information, auditory information, procedural information Semantic code LTM relies heavily on meaning of material Formation of associations between items in LTM Higher false alarm rate for semantically related words in recognition tasks Categorical structure of recall - grouping of similar objects into categories Long-term Memory.23. 9

10 Metacognition Ability to think about our cognitive processes We generally know whether we know something or not, even before we can answer the question We can think about strategies to get to a particular memory content We can use memory or mnemonic strategies to remember more information The tip-of-the-tongue phenomenon Sometimes, we know that we know something, but we cannot get there all the way Ability to describe the content (e.g., long vs. short name, sounds like, associations) Ability to predict time it will take to retrieve knowledge Long-term Memory

11 Memory consolidation General principle Not all information is retained in LTM Information has to be consolidated Integration with existing memories strengthens memory trace Multiple pathways Content of memories is stored in different locations all across the brain, depending on modality and type of memory Declarative: stored in cerebral cortex; important role of hippocampus in consolidation Procedural: Role of cerebellum and basal ganglia Long-term Memory

12 Levels of Processing Theory (Craik & Lockheart, 1972) Memory storage varies by the type of encoding The type of processing of to be remembered material determines how much of the material is later recalled Information that is processed shallowly is not retained as well as information that is processed more deeply Examples Processing of physical features of words (capitalized?) Phonological processing (rhyming) Semantic processing (what is the meaning of word?) Self-referential processing (how does it related to me?) Long-term Memory

13 Memory as a constructive process Memories are integrated Memories are integrated into larger structures (schemata) reflecting expectations / beliefs Memory for meaningful material is best Memory is biased by expectations and fills in missing pieces Examples Bartlett s experiments on Schemata (1932) Cultural framework of autobiographical memories Memory for text Schemata relevant for construction of understanding in text comprehension Long-term Memory

14 Memory loss: Amnesia Retrograde amnesia Loss of memory for events prior to a trauma Mild retrograde amnesia occurs frequently (e.g., after a concussion) Retrograde amnesia can diminish over time Anterograde amnesia Loss of memory for events after a trauma Best known case: H.M. Effects of amnesia Affects declarative memory (explicit memory) Procedural memory and implicit memory can still be intact Long-term Memory