Long-Term Memory PDF

LONG-TERM MEMORY STRUCTURE All information encoded in LTM is semantic in nature Semantic codes combine to form proposition Long capacity in terms of space and duration of memory representations Well organized Korsakoff’s syndrome: condition causing the destruction of areas in the frontal...

LONG-TERM MEMORY STRUCTURE All information encoded in LTM is semantic in nature Semantic codes combine to form proposition Long capacity in terms of space and duration of memory representations Well organized Korsakoff’s syndrome: condition causing the destruction of areas in the frontal and temporal lobes, which causes severe and permanent impairments in memory caused by a prolonged deficiency of vitamin B1, from chronic alcoholism Amnesia: loss of memory and/or ability to learn Retrograde: loss of memory of more recent memory before trauma but able to remember memories more distant and form new memories Anterograde: inability to form new memories Distinguishing Between Long-Term Memory and Short-Term Memory Long-term memory (LTM) is the system that is responsible for storing information for long periods of time Archive of information about past events SERIAL POSITION CURVE Primacy effect: superior memory for stimuli presented at the beginning of a sequence memory is better for words at the beginning and at the end of the list than for words in the middle because participants have more time to rehearse earlier words Recency effect: superior memory for stimuli presented at the end of a sequence most recently presented words are still in STM CODING IN LONG-TERM MEMORY Although all three types of coding (visual, auditory, semantic) can occur in LTM, semantic coding is the predominant type of coding in LTM illustrated by the kinds of errors that people make in tasks that involve LTM misremembering the word tree as bush would indicate that the meaning of the word tree (rather than its visual appearance or the sound of saying “tree”) is what was registered in LTM Recognition Memory Recognition memory: the identification of a stimulus that was encountered earlier Pre-training: present a stimulus Test: present the same stimulus plus others that were not presented LOCATING SHORT- AND LONG-TERM MEMORY IN THE BRAIN STM and LTM are separated in the brain, but there is some evidence for overlap Neuropsychological Studies Single dissociation: when a lesion to brain area X impairs the ability of a patient to do task A but not task B brain area X and task A are associated brain area X and task B are dissociated Double dissociation: when damage to area X impairs the ability to do task A but not task B, and damage to area Y impairs the ability to do task B but not task A 2 areas have complementary processing some patients with functioning STM can’t form new LTMs (H.M.) Some patients who have poor STM but functioning LTM (K.F.) Very low digit span & reduced recency effect Brain Imaging activation of different areas for STM and LTM TYPES OF LONG-TERM MEMORY TYPES OF LTM: Explicit memory: declarative memory (conscious) Episodic memories: for personal experiences Semantic memories: for knowledge or facts Implicit memories: non-declarative (unconscious) Procedural memory: how to do things Priming: a change in response to a stimulus caused by the previous presentation of the same or a similar stimulus Classical conditioning: stimulus-response associations Episodic and Semantic Memory (Explicit) DISTINGUISHING BETWEEN EPISODIC AND SEMANTIC MEMORY Episodic memory: involves mental time travel: the experience of traveling back in time to reconnect with events that happened in the past Involves what/when/where Semantic memory: involves accessing knowledge about the world without remembering a personal experience THE SEPARATION OF EPISODIC AND SEMANTIC MEMORIES Neuropsychological Evidence K.C.: suffered severe damage to his hippocampus and surrounding structures lost his episodic memory  semantic memory is largely intact Italian woman: damage caused by encephalitis Loss of semantic memory Intact episodic memory Brain Imaging Evidence while there is overlap between activation caused by episodic and semantic memories, there are major differences CONNECTIONS BETWEEN EPISODIC AND SEMANTIC MEMORIES when we are learning facts (potential semantic memories), we are usually simultaneously having a personal experience (episodic memory) EPISODIC MEMORIES CAN BE LOST, LEAVING ONLY SEMANTIC MEMORIES When memory is recent, both episodic and semantic memory are present When memory is far, episodic memory fades, leaving only semantic memories to be remembered SEMANTIC MEMORY CAN BE ENHANCED IF ASSOCIATED WITH EPISODIC MEMORY semantic memories that have personal significance are easier to remember SEMANTIC MEMORY CAN INFLUENCE OUR EXPERIENCE BY INFLUENCING ATTENTION Chess Experiment semantic memory can influence how people allocate their attention Priming, Procedural Memory, and Conditioning (Implicit) PRIMING Priming: when the presentation of one stimulus (the priming stimulus) changes the response to a subsequent test stimulus (the test stimulus) Negative priming: causes a decrease in the speed or accuracy of response to the test stimulus) Positive priming: which causes an increase in speed or accuracy of the response to the test stimulus Repetition priming: when the test stimulus is the same as or resembles the priming stimulus Conceptual priming: when the enhancement caused by the priming stimulus is based on the meaning of the stimulus Graff’s Implicit memory experiment Compared: Amnesic patients, Korsakoff patients, and control Results:  Recall experiment: amnesia patients had poor recall compared to the two control groups (confirms the poor explicit memory) Implicit memory test: the amnesia patient performed just as well as the controls Warrington & Weiskrantz’s experiment Tested Korsakoff patients Results: improvement of performance represents an effect of implicit memory because the patients learned from experience even though they couldn’t remember having had the experience Propaganda effect: participants are more likely to rate statements they have read or heard before as being true, simply because they have been exposed to them before PROCEDURAL MEMORY Procedural memory (skill memory): memory for doing things that usually require action We do not remember where or when we learned many of our basic skills No consciousness of how we do them H.M. Mirror drawing experiment Gradual improvement of a practiced skill without remembering any of the practice that led to this mastery LTM: ENCODING & RETRIEVAL Encoding: the process of acquiring information and transferring it into LTM Ex.: a word can be encoded by repeating it over and over, by thinking of other words that rhyme with it, or by using it in a sentence Retrieval: process of transferring information from LTM to working memory Shereshevsky’s “perfect” memory could encode long lists of words, addresses, digits events in a short period of time and recite them perfectly forward and backward Technique: “see” everything told to him or everything he read as a sequence of images Relied on synaesthesia Propositions Propositions: semantic content of a statement/idea/event any piece of such statement to which you can assign a “truth” value (T or F) Mary is Canadian (T/F) = proposition  Banff is not in Alberta (T/F) = proposition Caroline kicked (no T/F) = not a proposition Used as ways of encoding knowledge in logic and artificial intelligence SPATIAL RELATIONS Any given scene can be described in a myriad of ways Chances are, we encode some, but not all these possible ways Propositional representation in LTM: The Galileo Story Subjects heard/read a long paragraph Results: Semantic violation was correctly detected: no significant difference between sentences that preserve meaning The gist is what is being encoded Kintsch’s study on memory for propositions Sentences varying in: number of propositions number of content words Results: Harder to fully recall sentences with more propositions (more complex) twice as much partial recall for multi-propositional sentences We retain propositions from sentences Constructive Memory: Turtle Study All experimental sentences had similar structures with different prepositions/verb particles and final pronouns Results: Encoding the relational position of things Mental models Relation between proposition and images It includes a “reference” to the discourse/context It includes inferences drawn by the hearer/reader a logical/semantic description of the sentence does not always suffice to represent/encode real world events Mental Images Mental images can be anything (imagination, not viewing) AS PERCEPTION: relies on different properties of images Allocentric: viewer-entered “3D”: what is activated cannot be what is imagined AS EXPLANATIONS fundamental difference between empirical phenomena that reveal properties of mind and ones that reveal what a subject knows or remembers AS REPRESENTATIONS Encoding: Getting Information Into Long-Term Memory Rehearsal: process of repeating information over and over can be used to keep information in STM/working memory doesn’t guarantee that information will be transferred into LTM MAINTENANCE REHEARSAL AND ELABORATIVE REHEARSAL Maintenance rehearsal: repeating without any consideration of meaning or making connections with other information helps maintain information in STM/WM not an effective way of transferring information into LTM Elaborative rehearsal: when you think about the meaning of an item or make connections between the item and something you know more effective at transferring information into LTM LEVELS-OF-PROCESSING THEORY Levels-of-processing theory: memory depends on how information is encoded, with “deeper” processing resulting in better encoding and retrieval than “shallow” processing THE BASICS OF LEVELS OF PROCESSING depth of processing is determined by the nature of the task during encoding Shallow processing occurs when attention is focused on physical features involves little attention to meaning occurs during maintenance rehearsal Deep processing focuses on an item’s meaning and relating it to something else involves close attention occurs during elaborative rehearsal results in better memory than shallow processing THE DIFFICULTY IN DEFINING DEPTH OF PROCESSING based mainly on common sense desert island task causes deeper or shallower processing than the fill-in-the- blanks task results in deeper processing no procedure was offered to define depth of processing independently of memory performance RESEARCH SHOWING THAT ENCODING INFLUENCES RETRIEVAL Placing Words in a Complex Sentence memory for a word is much better when the word is presented in a complex sentence complex sentence creates more connections (acting as cues) between the word to be remembered and other things Forming Visual Images paired-associate learning: a list of word pairs is presented participants who had created images remembered more than twice as many words as the participants who had just repeated the word pairs Linking Words to Yourself self-reference effect: Memory is better if you are asked to relate a word to yourself Participants were more likely to remember words that they rated as describing themselves Generating Information Generation effect: generating material yourself enhances learning and retention, rather than passively receiving it Organizing Information The memory systems are designed to organize information so it can be accessed more efficiently participants spontaneously organize items as they recall them Retrieval cue: a stimulus (word) that helps a person remember information stored in memory Participants tended to organize their responses in the same way the trees were organized Testing Being tested on the material to be remembered results in better memory than re-reading it Testing effect: enhanced performance due to testing Retrieval: Getting Information Out of Memory RETRIEVAL CUES Retrieval cues: as words or other stimuli that help us remember information stored in our memory Cued Recall Free recall: participant is simply asked to recall stimuli  Cued recall: participant is presented with retrieval cues (stories/elaborations) to aid in recall of the previously experienced stimuli retrieval cues aid memory Increased percentage of words recalled retrieval cues are significantly more effective when they are created by the person whose memory is being tested MATCHING CONDITIONS OF ENCODING AND RETRIEVAL Another kind of “hint” (cue) that can help with retrieval: returning to a specific location Retrieval can be increased by matching the conditions at retrieval to the conditions that existed at encoding Encoding Specificity Encoding specificity: we encode information along with its context the best recall occurred when encoding and retrieval occurred in the same location participants did better when the testing condition matched the study condition State-Dependent Learning State-dependent learning: learning that is associated with a particular internal state (ex: mood or state of awareness) memory will be better when a person’s internal state/mood during retrieval matches his or her internal state/mood during encoding Transfer-Appropriate Processing Transfer-appropriate processing: memory performance is enhanced if the type of task at encoding matches the type of task at retrieval better performance when the same type of task happens during both encoding and retrieval EVERYDAY MEMORY & MEMORY ERRORS Autobiographical Memory: What Has Happened in My Life Autobiographical memory: recollected events that belong to a person’s past can also contain semantic components the relative proportions of episodic and semantic components is defined by how long ago the event to be remembered occurred Recent: episodic (emotion, perceptual details) Distant: semantic (facts) THE MULTIDIMENSIONAL NATURE Autobiographical memories are multidimensional because they consist of spatial, emotional, and sensory components  If one component is missing = some loss of autobiographical memory Memory Can Be Modi ed or Created by Suggestion People are suggestible & information presented by others can influence a person’s memory for past events THE MISINFORMATION EFFECT Misinformation effect: misleading information presented after a person witnesses an event can change how the person describes that event later misleading post-event information: misleading information Presenting Misleading Post-event Information MPI is then presented (naturally) to one group of participants before their memory is tested and is not presented to a control group effect of MPI is determined by comparing the memory reports of participants who received this misleading information to the memory reports of participants who did not receive it MPI can alter not only what participants report they saw, but their conclusions about other characteristics of the situation The misinformation effect shows not only that false memories can be created by suggestion but also provides an example of how different researchers can interpret the same data in different ways MPI as Replacing the Original Memory Memory trace replacement hypothesis: MPI impairs or replaces memories that were formed during the original experiencing of an event re-consolidation (reactivating a memory) can create the potential for forming new memory traces MPI as Causing Interference Retroactive interference: occurs when more recent learning (MPI) interferes with memory for something that happened in the past (the actual event) the old information isn’t eliminated by the new one; it is simply interfered with MPI as Causing Source Monitoring Errors Source monitoring: a person incorrectly concludes that the source of his or her memory for the incorrect event is due to the experience and not a misleading information introduced to them MPI is mistakenly identified as what was originally experienced DRM false memory effect False memory to the lure is often as strong as accurate memory for target items Spreading activation to related words converge on the mis-remembered word and makes it more ‘available’ fi Eyewitness testimony Information can be changed by elaboration or by misleading post-event information Results: changing the strength of the verb (crashed vs hit) changed the perception of speed