Explicit-Implicit Memory LTM Processes 1 Explicit-Implicit Memory

Separable Memory Systems? Locating memory in the brain Neuropsychology Hippocampus is responsible for encoding new long-term memories Henry Molaison (H.M.) – surgery for epilepsy Clive Wearing- encephalitis K.F. – brain injury in a motorbike accident

Separable Memory Systems? Neural evidence? Korsakoff’s Syndrome Lesions to frontal and temporal lobes Due to Vitamin B1 deficiency Often associated with alcoholism Anterograde Amnesia Inability to encode new information Patient HM Retrograde Amnesia Inability to remember information about past The hard drive has been “erased” Scene from Memento.

Separable Memory Systems? Evidence from dissociations on memory tasks Single dissociation Lesion ‘A’ impacts task X, but not task Y Double dissociation Lesion ‘B’ impacts task Y, but not task X Or, two experimental manipulations have different effects on two different dependent variables Patient STM Functions LTM Functions CW & HM OK Impaired KF Double Dissociation

Separable Memory Systems?

Separable Memory Systems? Implicit/non-declarative: unconscious 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: unconscious memory Episodic: personal events/episodes Semantic: facts, knowledge

Proposed LTM System Explicit memory (declarative memory) Consists of semantic memory and episodic memory Conscious and effortful processing Assessed with direct memory tests Free recall Cued recall Recognition Double dissociation between episodic and semantic memory Patient Semantic Functions Episodic Functions K.C. OK Impaired I.W.

Proposed LTM System Implicit memory (non-declarative memory) Information is learned and stored, but without Memory “implicitly” influences behavior Consists of procedural memory Like classical conditioning Assessed with indirect memory tests Influenced by information encountered in the past Stem-completion Fragment-completion Studied Stem Completion Fragment 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) Had anterograde amnesiacs and normal people study word lists Later, given direct and indirect memory tests Free recall Recognition Word fragment identification (study donkey, fragment = d _ _ k _ y) Word stem completion (study donkey, stem = don_ _ _)

Neuropsychological Evidence for Explicit/Implicit Division Warrington and Weiskrantz (1970) Results

Neuropsychological Evidence for Explicit/Implicit Division Graf, Shimamura, and Squire (1985) Subjects (normals and amnesiacs) rated the likability of words Subjects recalled studied words or completed word stems

Process Dissociation Framework Explicit memory and direct memory tests 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, the way information is encoded will influence how it can be retrieved

Process Dissociation Framework Blaxton (1989) examined process-dissociation in “normals” Encoding processes/tasks Data-driven vs. Conceptually-driven Retrieval tasks Study Conditions Test Conditions Read (data-driven) Generate (conceptually-driven) Word Fragment (data-driven) Grapheme Cue Semantic Cue   Knowledge Question bashful shy : ba____ B_SH_U_ bushel timid Which of the seven dwarves comes first alphabetically? cheetah cougar : ch____ _H_ _ TH cheetohs jaguar What is the fastest animal on the planet? copper tin : co_____ C_ PP_ _ chopper bronze What metal makes up 10% of yellow gold? plague sick : pl_____ P_ _ GU _ vague epidemic What disease was called the “Black Death”?

Process Dissociation Framework Blaxton (1989) Results Data-Driven Retrieval Tests Conceptually-Driven Retrieval Tests