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Episodic memory: Retrieval processes

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  1. Episodic memory: Retrieval processes • systematic study of role of retrieval processes in remembering started with work of Canadian psychologist Endel Tulving (who also introduced distinction between episodic and semantic memory)

  2. Episodic memory: Retrieval processes • given that retrieval cues are important to access information in episodic memory: • What makes the best retrieval cue to recall words from • list? • Perhaps, most strongly associated word in our language? • target : sky weak associate: clear • strong associate: blue

  3. Episodic memory: Retrieval processes • systematic manipulation of retrieval cues • Tulving & Osler, 1968 • at study: CITY – dirty • at test: free recall ?? • cued recall with original cue dirty ???? • cued recall with new high assoc. village ???? • findings: + cued recall better than free recall • + original cue better than new highly associated cue (not studied)

  4. Episodic memory: Retrieval processes • Tulving & Osler, 1968 • finding: + original cue better than other highly associated cue • -> association between cue and target in language as such not critical • -> critical whether cue was present when target was originally encountered

  5. Episodic memory: Retrieval processes • subsequent generalization: • to be effective, retrieval cue does not have to be present at encoding literally; cue just has to bring to mind what person thought about at encoding • Study: The fish attacked the swimmer • Test Group 1: What was the sentence that had to do with ‘shark’? • Test Group 2: What was the sentence that had to do with ‘fish’? • Cue in Group 1 more effective than cue in Group 2

  6. Episodic memory: Retrieval processes • further evidence that specific way in which info was thought about at encoding determines effectiveness of retrieval cue: • experiments by Bransford et al. (1974) • Study –Group 1: the man tuned the PIANO • Study –Group 2: the man lifted the PIANO • Cued recall: something heavy ?? • something melodious ?? • Results: Group 1 remembers PIANO better with second cue Group 2 better with first cue

  7. Episodic memory: Retrieval processes • theoretical interpretation of relationship between info at encoding and cue at retrieval: • encoding-specificity principle (Tulving & Thomson, 1973) • specific encoding operations determine what is stored, and what is stored determines what retrieval cues are effective in providing access to it

  8. What would be an effective cue to recall this picture?

  9. Episodic memoryRetrieval processes • further research on factors that influence intricate interplay between encoding and retrieval: • context-dependent retrieval • state-dependent retrieval • examples of external context: • + room in which episode took place • + peculiar smell at time of episode • examples of states of mind: • + being on drug • + being in particular mood (feeling sad) • -> external context or states of mind, when sufficiently encoded, can serve as powerful retrieval cue

  10. Research findings on context- and state-dependent retrieval • typical finding: • when context or state is same at encoding and retrieval • -> better performance than when it is different

  11. Context- and state-dependent retrieval:What are the limits? • external context and internal states don’t always work well as cues • -> most effective when no other retrieval cue available • e.g. weaker in cued recall than in free recall • -> states and context need to be consciously processed and important for experience at encoding to allow for subsequent benefits as cues • -> ‘experiential context’ most critical • e.g. when compared in same experiment, match in mood between encoding and retrieval more important than match in external context (Eich, 1995)

  12. Episodic memory: Retrieval processes • encoding-specificity principle (Tulving & Thomson, 1973) • specific encoding operations determine what is stored, and what is stored determines what retrieval cues are effective in providing access to it • -> leaves room for uniqueness of encoding in different individuals (subjective encoding) • -> benefits of cues for retrieval may vary from individual to individual • application: helping somebody to try and remember another person’s name

  13. Encoding-specificity principle: Implications • encoding-specificity principle • specific encoding operations determine what is stored, and what is stored determines what retrieval cues are effective in providing access to it • problem for empirical research: • how do we know what person encodes in the first place (in terms of experience)? • -> can we ever distinguish between loss of access vs loss of availability (retrieval failure vs true forgetting) ? • Schacter: probably not at cognitive level, • in principle yes at neural level

  14. Long-term memory (LTM):Conceptual distinction of two different types • Tulving 1972/1983: • distinction between episodic memory and semantic memory • episodic memory: remembering the past • - memory for episodes / events distinct in time and space • - associated with ‘mental time travel’ • - conscious recollection of personal past experience • (‘me’-ness) • semantic memory: knowing about things learnt in the past • - memory for world knowledge • - timeless; does not rely on ‘mental time travel’ • - does not involve conscious recollection • - shared with others

  15. Episodic memory versus Semantic memory • Examples: • retrieving information from episodic memory: • ‘in last term’s course on astronomy, my teacher explained that the solar system has nine planets’ • retrieving information from semantic memory: • ‘the solar system has nine planets’

  16. Types of world-knowledge stored in semantic memory • + meaning of words(vocabulary) • what is empathy? • + properties and structure of objects (perceptual, functional) • what does an aardvark look like? • what is an abacus made for? • + structure and sequence of events (social, natural, and other) • what usually happens when you enter a restaurant? • how does an earthquake develop? • + knowledge about people (incl. self) • who was Willy Brand? • when is my birthday? concepts

  17. Semantic memory:What is research about? • most psychological research on: • + how is information in semantic memory organized? • -> relates to question with long history in philosophy and linguistics: • what is the relation between different concepts in terms of their meaning? • e.g. what is the relationship between apples and kiwis or apples and peas? • Aristotle: “concepts should be properly and logically defined so as to avoid reasoning errors”

  18. Semantic memory:What is a concept? • pragmatic answer: the meaning of a word… • ….something that allows us to answer ‘what’ questions • e.g. what is a dog? What is ecphory? • more formal answer from dictionary: • (1) a general idea derived or inferred from specific instances • (2) something formed in the mind, a thought or notion • -> stresses relationship to categorization • -> stresses ‘mental’ nature (how we think about world)

  19. Semantic memoryWhat is a concept? • why is it important to have concepts/categories? • e.g. dog • Baddeley: • “concepts allows us to refer to what poodles, bull terriers, and great danes have in common” • -> intimately related to understanding of the world • -> potential for inferences/predictions • e.g. encountering animal that looks like dog -> how will it behave?

  20. Psychological research on organization of concepts in semantic memory • general question addressed: • Are concepts organized in a strictly logical manner? • starting point for research: • each concept is specified by fixed combination of semantic features • -> more specific question following: • Are different concepts organized in hierarchy according to shared features? • e.g. fruit -- apple -- peach

  21. Psychological research on organization of concepts in semantic memory • cognitive task used to address organization: • sentence verification task • “a canary has feathers” yes/no • “a shark can fly” yes/no

  22. Hierarchical nesting of conceptssuggested by Collins and Quillian (1969) hierarchical model proposed in combination with idea of spreading activation and cognitive economy

  23. Finding in support of Collins & Quillian’s model • major finding in support of hierarchical organization: • RTs for sentence verification change systematically with # of levels of hierarchy involved

  24. Subsequent problems with Collins & Quillian’s model + many hierarchical effects in RT disappear once frequency of properties in language usage is taken into account (Conrad, 1972) e.g. dog is an animal vs dog is a mammal + some exemplars of a category are verified more rapidly than others: robin is a bird vs penguin is a bird -> prototypicality effect why??

  25. Subsequent problems with Collins & Quillians model/findings + systematic differences in RT for negative sentences that have to do with degree of semantic relatedness between concepts poodle is a bird vs poodle is a mineral why?? + how can we come up with the proper hierarchy in the first place? e.g. how does ‘pet’ fit in?

  26. Subsequent modifications tothe model: Collins & Loftus’ ‘spreading activation theory’ • to deal with critique of original Collins & Quillians model • + no more strict hierarchical organization • + introduction of different semantic distances between concepts (to account for relatedness effects) • -> flow of activation between neighboring nodes varies according to distance • + introduction of different types of links: • ‘is a’ ‘is not a’ ‘has’ ‘can’ ‘cannot’

  27. Subsequent modifications tothe model: Collins & Loftus’ ‘spreading activation theory’ (different types of links not shown)

  28. Collins & Loftus’ ‘spreading activation theory’ • additional advantage of model: • allows to explain semantic priming effects • Meyer & Schvaneveldt(1971): • lexical decision task: butter -- Is it a word or not? • bunner -- Is it a word or not? • PRIME TARGET • a) bread ---- butter?? -> faster response to target if b) doctor --- butter?? preceded by semantically related prime (a) • -> most direct evidence for spread of activation

  29. Critique of Collins & Loftus’ ‘spreading activation theory’ • introduced to account for limited findings obtained with specific paradigms (i.e. sentence verification, lexical decision tasks) • -> ability to account for findings with other tasks? • e.g., semantic comparisons • complexity and elaborate processing rules don’t make it parsimonious • e.g. many different types of links necessary • prototypicality effects still difficult to explain in context of theory