10.+Memory+Systems

March 13, 2015
 * Memory Systems**

Organization of semantic memory Dissociation
 * Outline**
 * Content addressable memory
 * Semantic networks
 * Different memory systems
 * Evidence from amnesia

Content addressable memory: the content of the memory is the storage address Organization of memory Semantic Networks
 * Organization of Memory**
 * In a library, Moby Dick is stored at location 3263827
 * You have to look up the number and then go find the book
 * In our memory, Moby Dick is stored at location Moby Dick
 * No additional lookup required
 * As if you walk into a library, yell out the title of a book, and the book jumps out and runs to you.
 * This is the only way we can manage so much so quickly
 * Does Pam from the Office have a small intestine?
 * The answer is not in a memory
 * There's no "book" to jump out at you
 * But our memory system can find an answer anyway
 * Concepts are represented by nodes
 * Nodes are connected by links
 * It's a //semantic// network because:
 * the nodes have semantic meaning
 * Links are based on semantic relationships


 * Implicit vs. Explicit Memory**
 * Two types of memory test
 * Explicit memory test:
 * you are directly asked questions
 * Implicit memory test:
 * task performance is influenced by prior events, but you may be unaware of the influence (or that you are even being tested)
 * Jacob and Dallas (1981): Participants saw a list of words and answer questions about the words
 * E.g., Platypus
 * Letter: does it contain the letter L?
 * Rhyme: Does it rhyme with purse?
 * Semantic: is it an animal?
 * Half the subjects are given an explicit test
 * Recognition
 * Half the subjects are given an implicit test
 * Words flashed briefly (25 ms); Subjects must identify the word
 * Results:
 * Explicit test: Level of processing affected recognition (letter condition did worse than semantic condition)
 * Implicit test: Levels of processing did not affect identification
 * Depth of processing:
 * Does affect explicit memory
 * Does not affect implicit memory
 * When two systems appear to be different, it's called a dissociation

Squire's taxonomy of memory How we know whether these are truly distinct systems: How to disrupt one of the systems: brain damage
 * Dissociation**
 * Declarative (Explicit)
 * Semantic - knowledge
 * Episodic - knowledge of an episode (i.e., associated with a time, a place, etc.)
 * Non-declarative (implicit)
 * Procedural (riding a bike)
 * Priming (faster to think of a word)
 * Conditioning (bell elicits salivation)
 * Non-associative (habituation, sensitization)
 * Dissociation: If you can disrupt one but not the other, they're different systems
 * Boat horn study: conditioning vs. episodic
 * Training: Seeing the color blue is paired with hearing a boat horn (it's supposed to be loud and painful)
 * Test: How do the participants respond to seeing blue?
 * Control participant
 * Conditioning: fear, sweating
 * Episodic: They say "blue signaled shock earlier"
 * Patient with amygdala damage
 * Don't show fear response; no conditioning
 * But can remember that the color blue signaled the shock earlier; episodic still intact
 * Patient with hippocampal damage
 * Show a fear response (conditioning)
 * Don't remember that blue signaled the shock earlier; no episodic memory
 * Double dissociation: change in A does not affect B, and change in B does not affect A (as opposed to single dissociation, where some people can't do A, but normal people can do both A and B)
 * Because there is a double dissociation, conclude that they are separate systems

Retrograde Amnesia: cannot remember events prior to brain damage Anterograde Amnesia: cannot remember events that occur after brain damage
 * Amnesia**

EP suffered an acute virus infection that destroyed part of his brain. Most of his mental facilities remained intact, but the hippocampus was destroyed.
 * Lacks episodic memory. Doesn't remember meeting experimenters before, or what he's done in the last 15 minutes
 * Can't record new memories, but his old memories from before the brain damage are intact.
 * Evidence of implicit memory: lets experimenters in the door faster
 * EP suffers from anterograde amnesia

Typical anterograde amnesia: Case of H.M. Warrington & Weiskrantz (1970)
 * Anterograde Amnesia**
 * Impaired:
 * New declarative memory: can't explicitly remember new facts or events
 * Intact:
 * short-term working memory
 * conditioning
 * priming/familiarity
 * procedural learning
 * H.M. had severe epilepsy in his temporal lobes, so he was operated on. Hippocampus removed.
 * Could:
 * recall events from his childhood
 * engage in conversations
 * recall semantic memory from before the operation
 * Could not:
 * recall events that just happened
 * recall new facts
 * remember new faces
 * Subjets see a list of words (e.g., cheese) and are tested with:
 * Free recall (recall all of the words) - explicit
 * Cued recall (recall all of the foods) - explicit
 * Word completion (che___) - implicit (priming)
 * Results: amnesiacs performed worse than controls in free recall and cued recall conditions. Amnesiacs performed just as well at word completion.
 * Amnesiacs had preserved implicit priming

Cermak et al. (1993): Participants see 40 non-famous names. Given a test and told to identify famous names. Told: if you recollect studying it, it's not famous.
 * Shown previously seen names and new names, asked to judge whether or not they're famous.
 * Results:
 * Amnesia condition: judged higher percentage of previously seen names as famous than with new names.
 * Familiarity without recollection
 * Control condition: no difference in judgment of previously seen vs. new names
 * Familiarity and recollection

Procedural dissociation
 * Procedural memory
 * H.M. improved at the mirror tracing task (trace a picture in the mirror. It's hard a[[image:mirror tracing.png width="288" height="191" align="right"]]nd requires procedural memory to improve)
 * Does not remember doing the task before (no explicit memory)
 * Tower of Hanoi
 * Amnesics and controls given the Tower of Hanoi over 2 days[[image:hanoi.png width="132" height="57" align="right"]]
 * Amnesics learned improved just as much as controls (implicit memory of how to accomplish the task)

Dissociations
 * Conditioning vs. Episodic
 * Boat Horn & EP
 * Retrograde vs. Anterograde
 * EP & HM
 * Priming/familiarity vs. Explicit
 * word lists
 * Procedural vs. Explicit
 * mirror tracing & towers of hanoi