Chapter 11

Chapter 11Forgetting1MemoryInternal record or representation of past experienceNot necessarily the same as the original experienceHistory & metaphorsSlate Filing cabinet Computer

2Types of MemoryMany different types of memory2 are important for our purposes:Working memory: short-term, no need to store each instance for future referencee.g. matching to sample: need to remember what the sample was only until you make the choiceSamples change from trial to trialReference memory: long-term, remember specific information for future referencee.g. maze training: remember lay-out of the maze, doesnt change across trials3Working Memory4Sample:Retention Interval:Choice:Remember greenTrial #1Remember redTrial #2Remember redTrial #3Reference Memory5StartFoodTrial #1Trial #3FoodStartTrial #2StartFoodGoal is always in the same place remember over time!Behaviorist View of MemoryNo need to discuss representationNo focus on storage & retrievalExperiences ability to change an organisms behaviour under certain conditionsStimulus control6ForgettingDeterioration in learned behaviour following a period without practiceDefined behaviourallyPerformance vs DescriptionNote: extinction is not the same as forgetting7Measuring ForgettingWorking memorySample (training)Retention interval (usually short seconds/minutes/hours)TestNext sample is differentReference memoryTrainingRetention interval (can be much longer days/weeks)TestSamples (training) are always the same8Free Recall MethodTrain, wait, testSee how much deterioration in performanceAll-or-nothing test of behaviourMay not be appropriate for complex tasksSome elements remembered, others not9Free RecallLearn:BananaInterestingAnnoyBookComputer

Recall:___________________________________________________________________________

10Prompted (Cued) RecallGive prompts to increase likelihood of behaviourTwo ways:Measure deterioration (same as free recall)prompts help with complex tasks where free recall task might lead to very low scoresMeasure number of prompts needed to produce behaviour11Cued Recall:Recall:Ba_________In_________An_________Bo_________Co_________12Learn:BananaInterestingAnnoyBookComputer

Relearning MethodReinstall original training procedure after retention periodHow many trials (or time) needed compared to original training to return to initial level of proficiency?Reacquisition13RelearningLearn :BananaInterestingAnnoyBookComputer

Trial #1Score = 2/5Recall:Banana__________Annoy____________________Recall:Banana__________AnnoyBook__________Trial #2Score = 3/5Recall:BananaInterestingAnnoyBookComputerTrial #3Score = 5/5Total Trials on Initial Learning = 3How many trials to relearn after a break (retention interval)? Difference = amount of forgettingRecognition MethodSubject only has to identify material previously learnedE.g., distinguish between original stimulus and a number of distracter stimuli15

RecognitionWhich words were on the list?BananaOrangeInterestingAnnoyUglyComputerTableApple16Learn:BananaInterestingAnnoyBookComputer

Delayed Matching to SampleShow S+Wait (Delay = Retention Interval)Choose from S+ and S-Working memory onlySampleDelayMatching17Extinction MethodTrain two subjects (groups of subjects)Put both on extinction, but one has delay between training and extinction and the other doesntCompare rate of extinction for two subjects18Extinction methods19Group 1 & 2Learning PhaseGroup 1ExtinctionbreakGroup 2ExtinctionCompare amount of timeGradient Degradation MethodEstablish stimulus control (discrimination training)Measure generalization gradientRepeated measure gen. grad. over timeIf generalization gradient flattens, forgetting20Gradient degradation21Training: Establish gradientNo ForgettingForgettingVariables in Forgetting22Is time a variable?Retention interval = Time between learning and testingGreater the interval, less retained (i.e., more forgetting)But, time is not an event (time doesnt account for forgetting)Need causal factors23Variables are:Degree of learning (overlearning)Prior LearningFacilitationInterferenceSubsequent LearningContext24OverlearningLearn to asymptote, then keep trainingLearning list perfectly, then practice a few more timesBetter recall for longerPoint of diminishing returnNot a linear relationship between overlearning and retentioni.e. 100% overlearning isnt twice as good as 50% overlearning

25Krueger (1929)Adults learn 3 lists of 12 one-syllable nounsList 1: go through list until they remember all 12List 2: learn list perfectly, then go through again for half as many trials as it took to learni.e. if they took 10 trials to learn perfectly, they go through list another 5 timesGroup 3: learn list perfectly, then go through again as many times as it took to learni.e. another 10 timesRelearn after various intervals26ResultsGreater amount of overlearning, less forgetting100% overlearning better than 50% overlearning50% overlearning way better than 0% overlearningi.e. difference between 100% & 50% was LESS THAN difference between 50% & 0%27Facilitation of Prior LearningPrevious experience makes something easier to rememberMeaningful material easier to retain than random materiale.g. Easier to learn a complete sentence than 12 random wordsPrior experience important in determining what is meaningful (e.g., words in known or unknown language)28DeGroot (1966)Arranged chess pieces on board as if in the middle of a gameChess masters and novices; 5 seconds to observeMasters reproduced arrangement 90% of time, novices only 40%Is this prior experience, or do chess masters forget less than other people?29Chase & Simon (1973)Chess pieces placed randomly on boardMasters no better than novices at recallPast learning of legal arrangements is what increased masters performance in deGroot (1966) study30Interference of Prior LearningProactive interferencePrevious learning interferes with recall of newer learning31Studying proactive interferencePaired Associate Learning (PAL) techniqueSubjects learn paired lists, tested with 1 item and must recall secondAll learn A-C list, but some previously learned A-B listIn testing, give A and ask to recall CThose with A-B learning have more difficulty recalling C when given A32PAL example1 group first learns:Red-AppleCloud-ShoeCat-ShelfPlate-SpoonCarpet-TentBoth groups then learn:Red-BookCloud-PaperCat-FencePlate-NotebookCarpet-Window33Both groups then RECALL:Red- ________Cloud- ________Cat- ________Plate- ________Carpet- ________Levine & Murphy (1943)Proactive interference with attitudesDetermine initial attitude towards communismLikert ScaleRead pro- and anti-communism passagesStudents who had prior pro-communist attitudes forgot anti-communist elements of passages but remembered pro-elements (and vice versa)Proactive interference because attitudes are not innate; effect of prior learning34Subsequent Learning (Interference)Inactivity during retention interval leads to less forgetting than activityImplies forgetting partly based on learning new materialJenkins & Dallenbach (1924)Recall (%)100

50Hours after learning tested0 2 4 6 8sleepawake35Retroactive InterferenceNew learning interferes with ability to recall earlier learningPAL technique (opposite order)Subjects learn A-C, but some then learn A-BTest by giving A and recalling CSubjects who learned A-B have worse recall for C e.g. forgetting old phone numbers, license plates, passwords36PAL exampleBOTH groups first learn:Red-AppleCloud-ShoeCat-ShelfPlate-SpoonCarpet-Tent1 group then learns:Red-BookCloud-PaperCat-FencePlate-NotebookCarpet-Window37Both groups then RECALL:Red- ________Cloud- ________Cat- ________Plate- ________Carpet- ________Order is just switched from last exampleContextLearning occurs in a contextVarious stimuli around the learnerThese stimuli serve as cues to evoke a behaviourIf stimuli absent, may have cue-dependent forgettingStimulus controle.g. forgetting names when in a different context38Context39

SDColour, size, shape, etcCue set, set of SDs, has changed! Less cues to signal correct response.Perkins & Weyant (1958)Train two groups of rats in two mazes, one black, one white1 minute retention intervalHalf of each group tested in original maze, half in maze of opposite colourOpposite colour rats did poorly compared to original maze tested rats 40Kamin (1957)Gave rats avoidance learning, tested at various retention intervals.Time of day, internal clockInternal physiological state cues recallinternal contextAvoidance (%)Retention Interval (hr) 0 12 24 36 48 60 72 84100

5041State-Dependent LearningTrain under a particular physiological state (e.g., drug condition) and test under various statesRecall best when in the same state as trainingDrug conditions: alcohol, caffeine, etc.Internal State: tired, level of stress, emotions, etc.42Application: ForagingFood Caching Cache: food storeRetrieval of food laterSpatial memoryWide variety of speciesAccuracy can be quite high for very long times43Application: Eyewitness TestimonyNotoriously poorBasic issue of retention interval and forgettingAlso the nature of the question used to retrieve information44Loftus & Zanni (1975)Subjects watched film of car accidentAsked Did you see / broken headlight?the subjects twice as likely as a subjects to say yesActually, no broken headlight shownReinforcement historyPrevious conditioning: the (definite article) implies presence; a implies possible presence45Loftus & Palmer (1974)Watch film of car accidentHow fast were the cars going when they hit each other?Underlined word replaced with smashed, collided, bumped, contactedSpeed estimates varied based on wording of questionReports of broken glass varied based on wording46Learning to Remember47Learning to RememberIn essence, improving learningPractice increases retentionTechniques:OverlearningMnemonicsContext cuesPrompts48OverlearningPractice beyond learninge.g. Tiger Woods putting practicee.g. Flash Cards (SAFMEDS)49MnemonicsRhymes, First LettersHOMES, Roy G. BivMethod of LociAssociate learned items with locations on a well-known routePeg Word System1 = bun, 2 = shoe, 3 = treeAlso works with visual1 looks like a pencil, 2 looks like a swan, 3 is a tricycle50Mnemonic example1 coffee cup imagine using a coffee cup as a pencil holder2 rubber ball imagine a swan holding a rubber ball in its beak3 printer imagine a printer printing a piece of paper with a tricycle on it4 yoga mat imagine trying to balance in yoga positions while on top of a table (4 legs)Etc.The more bizarre the image, the easier it is to remember (lack of interference)51Context CuesKeep context the sameStudy in classroomPay attention to habits, internal states52PromptsCreating S+sMemos, notes, calendar markingsOften dont contain all info, so just a reminder of what needs to be doneE.g. 3-Choice meetingString on finger, watch beep, cell phone reminders53