PSY 368 Human Memory Short Term Memory cont. Working Memory

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  • PSY 368 Human MemoryShort Term Memory cont.Working Memory

  • RemindersExam 1 one week from today (Feb 15)Review sheet posted, linked to syllabusExperiment 1 report also due 1 week from today

  • Experiment 1 assignmentExperiment 1 - Primacy and Recency Effects in Short-term Memory (modified from Neath & Surprenant book pg. 61)Download from BB assignments page. Find 3 friends willing to participateReport (Due Wednesday Feb. 15): The results for all subjects will be reported in class. Your assignment is to write a 2-3 page report that includes the following:brief description of the purpose and design of the experiment, including independent and dependent variablesbrief description of the participants, materials, and procedure of the study, written in your own wordsdescription of results and line graph of mean percentage recall by serial position discussion of conclusions that can be made from the results. Include answers to these questions:How long does short-term memory appear to last?How important is attention to retrieval from short-term memory?What kinds of everyday tasks in life use short-term memory?

  • Structural ModelMemory composed of storage structures that hold memories for a period of time Sensory memoryShort-term memory (STM)Long-term memory (LTM)

  • Structural ModelBrief review from last timeCapacity:Can hold 7 + or - 2 chunks(capacity)Chunking increases capacity of STMEncoding: Info mostly stored in auditory form (but some visual, some semantic)Duration: Brown/Peterson task: decay, gone by 15-20 secKeppel & Underwood; Waugh and Norman suggest interference as better explanationRetrieval:

  • Two groups of subjects given 3 trials following the Brown-Peterson task (letters) - Memory performance declined with each trialControl group given a 4th trial using lettersExperimental group switched to remembering digitsWickens, Born, & Allen (1963)STM DurationChanging the nature of the items to be remembered reverses the decline in performance due to proactive interference- release from proactive interferenceProactive interference: already learned info interferes with new informationRetroactive interference: new information interferes with old information (more on this in chapter 6)

  • *Experimental group, but not control group, performed perfectly; they were released from proactive interference

    Wickens, Born, & Allen (1963)STM DurationChanging the nature of the items to be remembered reverses the decline in performance due to proactive interference- release from proactive interference

  • *Proactive interference occurring as a result of semantic coding in STM5 groups of subjects given 3 trials of lists of 3 words each all from the same category where all list contained names of fruitWickens (1970, 1972, 1976)Group 1 names of fruitGroup 2 vegetable namesGroup 3 flower namesGroup 4 - names of meatsGroup 5 names of different professionsThen all groups given a 4 trial where all list contained names of fruitSTM Duration

  • Wickens (1970, 1972, 1976)STM Duration1st trial allgroups about 90% correctResults:2nd trial more words in same categoryall groups about 50%3rd trial words still in same category all groups 3545 %4th trial , shift to fruit categoryprofessions 80%, meat 50%, flowers 47%, vegetables 40% and fruit 32%

  • Wickens (1970, 1972, 1976)STM DurationResults:Conclusion: Interference rather than decay causes the drop in performanceInformation was coded using semantic information causing groups to confuse current list with previous lists

  • STM DurationDuration: STM is short store of about 15-20 sLoss of information initially thought to be due to decay. More recent work suggests interference more likely reason

  • STM RetrievalHow do we get information out of STM?Retrieval from STM appears to operate by searching STM contents one at a time (serial search)Sternberg (1966)Serial position recall curves: primacy and recency

  • STM Retrievalstudy short list of 1 to 6 items followed by test probe - must decide if probe item was in list, measured time to make Y/N responseTwo important variables were involvedThe number of letters in each listThe location of the letter in the memory probe in the beginning, middle, or endSternberg (1966)

  • Serial processingOperations being done one after anotherIt should take longer to retrieve four digits than to retrieve two digitsExhaustive serial processing the participant always checks the test digit against all digits in the set, even if a match were found partway through the listSelf-terminating serial processing the participant would check the test digit against only those digits needed to make a responseSTM RetrievalParallel processingSimultaneous handling of multiple operationsResponse times should be the same, regardless of the size of the set of items, because all comparisons would be done at onceSternberg (1966)

  • ResultsResponse times increased linearly with set size but were the same regardless of serial positionIt indicates that serial exhaustive model seems to be rightSubjects take longer to respond by probe (by 40 ms) when an additional item is added to the list Same results for probes that were in the list and probes that were not

    STM RetrievalConclusion: people search all items in STM when asked to retrieve an item (happens very fast)Automatic process - fast and efficient, done for every item doesnt stop once a match is foundSternberg (1966)

  • Serial Position Curve: Free recallSTM RetrievalPrimacy: better recall for items in the beginning of the list than those in the middleRecency:better recall for items at the end of the list than those in the middle

  • Models of STM propose that Primacy is due to more rehearsal for items at beginning of list - LTMRecency due to immediate dumping of items from STMFree recall CurveFrom Murdock (1962)Primacy: better recall for items in the beginning of the list than those in the middleRecency:better recall for items at the end of the list than those in the middleSTM Retrieval

  • Models of STM propose that Primacy is due to more rehearsal for items at beginning of list - LTMRecency due to immediate dumping of items from STMRecency is stronger effect than primacy in free recallFree recall Curve vs. serial recall curvesPrimacy: better recall for items in the beginning of the list than those in the middleRecency:better recall for items at the end of the list than those in the middledue to retrieval from STMFrom Klien et al. (2005)STM Retrieval

  • Modal Model of STM: SummaryDuration: STM is short store of about 20 s Capacity:Can hold 7 + or - 2 chunks(capacity)Chunking increases capacity of STMEncoding: Info mostly stored in auditory formRetrieval: Modal models suggest recency effects mostly due to STM retrieval

  • Problems with the Modal ModelsWhen distractor task is done after every list item preventing items from staying in STM, recency effect still occursPrimacy effects have also been shown to disappear when rehearsal is preventedLong-term recency effectsBaddeley and Hitch (1977) Rugby StudyQuestion: Which teams have you played this past season?Results:Recency effect: Recent games were recalled best.The total number of games played, not the amount of time gone by, best predicted forgetting.

  • More Recent ModelsCurrent models focus more on processing (than structures) and that include STM in some form (storage and manipulation of information)There are multiple models that have been called Working Memory, designed to account for similar sets of dataModels of WM assume:That STM is a storage unit and that WM = processes involved in completing a taskThat WM requires consciousness - includes info we are currently attending to

  • Working MemoryToday we will talk about 3 theories of WMBaddeleys model of WM (Baddeley, 1986, 2000)Cowans activation model (Cowan, 1988, 1995)Nairnes feature model (Nairne, 1988, 2001)

  • Baddeleys ModelCurrently the most influential modelBaddeley and Hitch (1974)Components of the model:Central executive controls the focus of attention Three subsystems under its controlVisuospatial sketchpadPhonological loopEpisodic buffer

  • Baddeleys ModelArticulatoryControlVisual scribe

  • Baddeleys ModelArticulatoryControlVisual scribe

  • Central ExecutiveThought to be an attentional controller, with two main modes of operation (Norman & Shallice, 1986):A semi-automatic conflict-resolution system, based on existing habits and requiring little attention.The supervisory attentional system (SAS), based on an attentionally limited executive.Major Functions:Direct attention to the task at handDivide attention between two or more tasks

  • Baddeleys ModelArticulatoryControlVisual scribe

  • Visuo-spatial SketchpadStores and manipulates visual and spatial information of images

    May be separate parts for visual info (color) and spatial info (orientation, location)Info enters through perception or internally generated visual imagesControls tasks like mental rotation and geographical search of a visual or mental imagelocationorientationcolor

  • Visuo-spatial SketchpadBaddeley (1992) found that subjects memory for chess patterns was more disrupted by a visual distractor task than an auditory oneShepard and Feng (1972)Imagine folding the shapes below to create a solid, with the shaded area as the base. Will the arrows meet head on?

    found that the time it takes to answer the question depends on the number of folds required

  • Baddeleys ModelArticulatoryControlVisual scribe

  • Episodic BufferBack-up storage - allows for recall when other systems are engaged with other tasksA storage system with a capacity of around 4 chunks of information in a multidimensional code.Multiple dimensions permit links between the subsystems, as well as with LTM & perception.Information is retrieved through conscious awareness consciousness pulls info together.Allows for the binding of previously unrelated concepts -- disrupting the executive does not impair binding, so it may be automatic/passive.Newest component of the model, not much research yet

  • Baddeleys ModelArticulatoryControlVisual scribe

  • Phonological LoopTwo parts: Phonological Store (PS) and Articulatory Control Process (ACP)PS - stores auditory info for 1-2 s and then it starts to decayACP - recodes visual info into auditory code for storage and controls rehearsal4 Main Effects in Serial Recall Task to account forPhonological similarity effectArticulatory suppression effectIrrelevant speech effectWord length effect

  • Phonological LoopDemosListen to list, recall words in orderRhinocerosZincGorillaTuberculosisMeaslesCalciumUraniumCarbonHippopotamusMumps

    Listen to list, recall words in orderPlanetMusicianLandPropertyTrumpetHouseStarCometOrchestraMoon

    Listen to list, recall words in order, while I read the words say the aloud BlockBrickStickBlueChewTrickPrickClueClickBlimp

    Read list, recall words in order, while I read the words say the aloud GoldCodeBoldHoldToldColdModeSlowedHopeGoad

    RecallListen to list, recall words in order, while I read the words say the aloud BronzeBookMagazineBikeCopperDressCopierSodaShoeRock

  • Phonological LoopDemosListen to list, recall words in orderRhinocerosZincGorillaTuberculosisMeaslesCalciumUraniumCarbonHippopotamusMumps

    Listen to list, recall words in orderPlanetMusicianLandPropertyTrumpetHouseStarCometOrchestraMoon

    Listen to list, recall words in order, while I read the words say the aloud BlockBrickStickBlueChewTrickPrickClueClickBlimp

    Read list, recall words in order, while I read the words say the aloud GoldCodeBoldHoldToldColdModeSlowedHopeGoad

    Listen to list, recall words in order, while I read the words say the aloud BronzeBookMagazineBikeCopperDressCopierSodaShoeRock

  • Phonological LoopMemory worse for items that sound alike than those that look alike or have similar meaningsVisual items are recoded to auditory for storage and rehearsal by ACPWhat happens if you prevent the recoding of visual information into auditory information?Works for both auditory presentation and visual presentation of the letters.Phonological Similarity Effect

  • Phonological LoopArticulatory Suppression EffectEngaging in an auditory task after study removes phonological similarity effect for visual itemsProcedure: Say the aloud over and over No re-coding of visual info by ACPPhonological info gets in directly, doesnt need re-codingAuditory presentation: PGTCD (similar sounding) harder to recall than RHXKW (different sounding)Visual presentation: PGTCD (similar sounding) recalled equally as RHXKW (different sounding)

  • Phonological LoopIrrelevant Speech EffectBackground speech presented during study decreases memory for visual itemsIrrelevant speech interferes with recoding of visual info to auditoryVisual info weak in WM Something stored in the visuospatial sketchpad, but this system not as efficient as the phonological loop

  • Phonological LoopWord-length EffectResultsRecall decreases as the length of time it takes to say a word increases.Rehearsal takes longer for longer words - cant rehearse as many timesBaddeley, Thomson, and Buchanan (1975)Retrieval from PS also takes longer due to auditory coding of itemsReading rate correlated with memory abilityDigit span depends on language - how long it takes to say numbers

  • Potential Problems with the modelSome of the supportive results cant be replicated (e.g., irrelevant speech effect)Model cant explain all results: why word-length effect is larger for visual than auditory items why it differs based on serial list positionModel is not precise in explanation of effects

    Baddeleys Model

  • Cowans Activation ModelCowan (1999)WM = info that is currently highly activated from STM or LTMFocus of attentionEmphasizes attentions role in activationActivation of info when attention is oriented to itActivation will decay to cause loss of info from WM

  • Cowans Activation ModelCentral Executive Focuses attention and other control processesCapacity of about 4 chunksDuration of 20s without reactivationSTMactivated items that are just outside of attention - passive storeThings within attentional focus are available to consciousness

  • Potential problems with the modelOnly general descriptions so specific predictions are hard to makeActivation is not operationally defined very well - when is something is activated?What causes decay? Passage of time isnt causalCowans Activation Model

  • Nairnes Feature ModelItems represented in WM as individual features (e.g., color, length, etc.)Features indicate presentation info (e.g., font, size, gender of voice, etc.) meaning info (e.g., what the item means, category, etc.)Features represented by -1 or +1 when studied (yes or no for a feature, 0 if no info for feature)Interference: Later items with same features overwrite feature info for previous items

  • Nairnes Feature Model Bold Lower Upper BlueSCHOOL +1 -1 +1 -1fish +1 +1 -1 -1 fish presented after SCHOOL- features in common can be overwritten - SCHOOL can become 0, -1, +1, 0- interferenceDuring retrieval, item features are compared with items in memory - lost features can be updated an...

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