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LTM Processes 1
Explicit-Implicit Memory
Separable Memory Systems?
Locating memory in the brain Neuropsychology Hippocampus is responsible for encoding new memories Henry Molaison (H.M.) – surgery for epilepsy Clive Wearing- encephalitis K.F. – brain injury in a motorbike accident
Separable Memory Systems?
Neural evidence? Anterograde Amnesia Inability to encode new information Patient HM Retrograde Amnesia Inability to remember information about past The hard drive has been “erased”
Korsakoff’s Syndrome Scene from Memento. Lesions to frontal and temporal lobes Due to Vitamin B1 deficiency Often associated with alcoholism Varied memory dysfunction
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Separable Memory Systems?
Evidence from dissociations on memory tasks Single dissociation Lesion ‘A’ impacts task X, but not task Y Double dissociation Lesion ‘A’ impacts task X, but not task Y Lesion ‘B’ impacts task Y, but not task X Or, two experimental manipulations have different effects on two different dependent variables Patient STM LTM Performance Performance CW & HM OK Impaired Double KF Impaired OK Dissociation
Separable Memory Systems?
Separable Memory Systems?
Implicit/Non-Declarative Memory Not-conscious memory Procedural (skill) memory Skill memory: memory for actions No memory of where or when learned Priming: previous experience changes response without conscious awareness Explicit/Declarative Memory Conscious memory Episodic: personal events/episodes Semantic: facts, knowledge
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Proposed LTM System
Explicit memory (declarative memory) Consists of semantic memory and episodic memory Requires conscious and effortful processing Assessed with direct tests of memory Free recall Cued recall Recognition Double dissociation between episodic and semantic memory Patient Semantic Functions Episodic Functions K.C. OK Impaired I.W. Impaired OK
Proposed LTM System
Implicit memory (non-declarative memory) Information is learned and stored, but without intent Memory “implicitly” influences behavior Consists of procedural memory Like classical conditioning Assessed with indirect tests of memory Performance is influenced by information encountered in the past Stem-completion Stem Fragment Fragment-completion Studied Completion Completion bashful bas_ _ _ _ b_sh_u_ plague pla_ _ _ p_ _ gu_
Neuropsychological Evidence for Explicit/Implicit Division
Anterograde amnesiacs cannot form new, explicit memories Relative to “normal” subjects, amnesiacs should... ...show poor performance on direct memory tests ...have roughly equal performance on indirect memory tests Warrington and Weiskrantz (1970) Anterograde amnesiacs and normal subjects studied word lists Given direct and indirect tests of memory Free recall Recognition Fragment identification (study donkey, fragment = d _ _ k _ y) Stem completion (study donkey, stem = don_ _ _)
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Neuropsychological Evidence for Explicit/Implicit Division
Warrington and Weiskrantz (1970) Results Free Recall Recognition 0.8 0.8
0.6 0.6
0.4 0.4
0.2 0.2 Proportion Correct Proportion Correct Proportion 0 0 Controls Amnesiacs Controls Amnesiacs
Word Fragment Completion Word Stem Completion 0.8 0.8
0.6 0.6
0.4 0.4
0.2 0.2 Proportion Correct Proportion Correct Proportion 0 0 Controls Amnesiacs Controls Amnesiacs
Neuropsychological Evidence for Explicit/Implicit Division
Graf, Shimamura, and Squire (1985) Subjects (normal, amnesiacs, alcoholics) rated the likability of words Implicit encoding No explicit forming of memories Subjects recalled words or completed word stems
Process Dissociation Framework
Explicit memory and direct memory tests Rely on conceptually-driven processes Retrieving semantic and episodic information requires recollection Conceptually-driven encoding benefits conceptually-driven retrieval Implicit memory and indirect memory tests Rely on data-driven processes Influence of implicitly encoded information requires a familiarity Data-driven encoding benefits data-driven retrieval Basically, how information is encoded will influence how it can be retrieved
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Process Dissociation Framework
Blaxton (1989) examined process-dissociation in “normals” Encoding processes/tasks Data-driven vs. Conceptually-driven Retrieval tasks Data-driven vs. Conceptually-driven Study Conditions Test Conditions Read Generate Semantic Cue (data- (conceptually- Word Fragment Grapheme Cue (conceptually- Knowledge Question driven) driven) (data-driven) (data-driven) driven) (conceptually-driven) Which of the seven dwarves bashful shy : ba____ B_SH_U_ bushel timid comes first alphabetically?
What is the fastest animal on cheetah cougar : ch____ _H_ _ TH cheetohs jaguar the planet?
What metal makes up 10% copper tin : co_____ C_ PP_ _ chopper bronze of yellow gold?
What disease was called the plague sick : pl_____ P_ _ GU _ vague epidemic “Black Death”?
Process Dissociation Framework
Blaxton (1989) Results
Word Fragment Completion Grapheme Cued Recall 100 100
80 80 Data-Driven 60 60 Retrieval Tests 40 40 20 20 0 0 Read Generate Read Generate
“Memory Performance” “Memory Encoding Condition Performance” “Memory Encoding Condition Semantic Cued Recall Knowledge Questions 100 100 80 80 Conceptually- 60 60 Driven Retrieval 40 40 Tests 20 20 0 0 Read Generate Read Generate
“Memory Performance” “Memory Encoding Condition Performance” “Memory Encoding Condition
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