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Forgetting 1. Memory Internal record or representation of past experience Not necessarily the same as the original experience History & metaphors Slate.

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Presentation on theme: "Forgetting 1. Memory Internal record or representation of past experience Not necessarily the same as the original experience History & metaphors Slate."— Presentation transcript:

1 Forgetting 1

2 Memory Internal record or representation of past experience Not necessarily the same as the original experience History & metaphors Slate  Filing cabinet  Computer 2

3 Types of Memory Many different types of memory 2 are important for our purposes: Working memory: short-term, no need to store each instance for future reference e.g. matching to sample: need to remember what the sample was only until you make the choice Samples change from trial to trial Reference memory: long-term, remember specific information for future reference e.g. maze training: remember lay-out of the maze, doesn’t change across trials 3

4 Working Memory 4 Sample: Retention Interval: Choice: Remember “green” Trial #1 Remember “red” Trial #2 Remember “red” Trial #3

5 Reference Memory 5 Start Food Trial #1 Trial #3 FoodStart Trial #2 Start Food Goal is always in the same place… remember over time!

6 Behaviorist View of Memory No need to discuss “representation” No focus on storage & retrieval Experience’s ability to change an organism’s behaviour under certain conditions Stimulus control 6

7 Forgetting Deterioration in learned behaviour following a period without practice Defined behaviourally Performance vs Description Note: extinction is not the same as forgetting 7

8 Measuring Forgetting Working memory Sample (training) Retention interval (usually short… seconds/minutes/hours) Test Next sample is different Reference memory Training Retention interval (can be much longer… days/weeks) Test Samples (training) are always the same 8

9 Free Recall Method Train, wait, test See how much deterioration in performance “All-or-nothing” test of behaviour May not be appropriate for complex tasks Some elements remembered, others not 9

10 Free Recall Learn: Banana Interesting Annoy Book Computer Recall: _______________ 10

11 Prompted (Cued) Recall Give prompts to increase likelihood of behaviour Two ways: Measure deterioration (same as free recall) prompts help with complex tasks where free recall task might lead to very low scores Measure number of prompts needed to produce behaviour 11

12 Cued Recall: Recall: Ba_________ In_________ An_________ Bo_________ Co_________ 12 Learn: Banana Interesting Annoy Book Computer

13 Relearning Method Reinstall original training procedure after retention period How many trials (or time) needed compared to original training to return to initial level of proficiency? Reacquisition 13

14 Relearning Learn : Banana Interesting Annoy Book Computer Trial #1 Score = 2/5 Recall: Banana __________ Annoy __________ Recall: Banana __________ Annoy Book __________ Trial #2 Score = 3/5 Recall: Banana Interesting Annoy Book Computer Trial #3 Score = 5/5Total Trials on Initial Learning = 3 How many trials to relearn after a break (retention interval)? Difference = amount of forgetting

15 Recognition Method Subject only has to identify material previously learned E.g., distinguish between original stimulus and a number of distracter stimuli 15

16 Recognition Which words were on the list? Banana Orange Interesting Annoy Ugly Computer Table Apple 16 Learn: Banana Interesting Annoy Book Computer

17 Delayed Matching to Sample Show S+ Wait (Delay = Retention Interval) Choose from S+ and S- Working memory only Sample Delay Matching 17

18 Extinction Method Train two subjects (groups of subjects) Put both on extinction, but one has delay between training and extinction and the other doesn’t Compare rate of extinction for two subjects 18

19 Extinction methods 19 Group 1 & 2 Learning Phase Group 1 Extinction break Group 2 Extinction Compare amount of time

20 Gradient Degradation Method Establish stimulus control (discrimination training) Measure generalization gradient Repeated measure gen. grad. over time If generalization gradient flattens, forgetting 20

21 Gradient degradation 21 Training: Establish gradient No Forgetting Forgetting

22 22

23 Is time a variable? Retention interval = Time between learning and testing Greater the interval, less retained (i.e., more forgetting) But, time is not an event (time doesn’t account for forgetting) Need causal factors 23

24 Variables are: Degree of learning (overlearning) Prior Learning Facilitation Interference Subsequent Learning Context 24

25 Overlearning Learn to asymptote, then keep training Learning list perfectly, then practice a few more times Better recall for longer Point of diminishing return Not a linear relationship between overlearning and retention i.e. 100% overlearning isn’t twice as good as 50% overlearning 25

26 Krueger (1929) Adults learn 3 lists of 12 one-syllable nouns List 1: go through list until they remember all 12 List 2: learn list perfectly, then go through again for half as many trials as it took to learn i.e. if they took 10 trials to learn perfectly, they go through list another 5 times Group 3: learn list perfectly, then go through again as many times as it took to learn i.e. another 10 times Relearn after various intervals 26

27 Results Greater amount of overlearning, less forgetting 100% overlearning better than 50% overlearning 50% overlearning way better than 0% overlearning i.e. difference between 100% & 50% was LESS THAN difference between 50% & 0% 27

28 Facilitation of Prior Learning Previous experience makes something easier to remember Meaningful material easier to retain than random material e.g. Easier to learn a complete sentence than 12 random words Prior experience important in determining what is meaningful (e.g., words in known or unknown language) 28

29 DeGroot (1966) Arranged chess pieces on board as if in the middle of a game Chess masters and novices; 5 seconds to observe Masters reproduced arrangement 90% of time, novices only 40% Is this prior experience, or do chess masters forget less than other people? 29

30 Chase & Simon (1973) Chess pieces placed randomly on board Masters no better than novices at recall Past learning of “legal” arrangements is what increased masters’ performance in deGroot (1966) study 30

31 Interference of Prior Learning Proactive interference Previous learning interferes with recall of newer learning 31

32 Studying proactive interference Paired Associate Learning (PAL) technique Subjects learn paired lists, tested with 1 item and must recall second All learn A-C list, but some previously learned A-B list In testing, give A and ask to recall C Those with A-B learning have more difficulty recalling C when given A 32

33 PAL example 1 group first learns: Red-Apple Cloud-Shoe Cat-Shelf Plate-Spoon Carpet-Tent Both groups then learn: Red-Book Cloud-Paper Cat-Fence Plate-Notebook Carpet-Window 33 Both groups then RECALL: Red- ________ Cloud- ________ Cat- ________ Plate- ________ Carpet- ________

34 Levine & Murphy (1943) Proactive interference with attitudes Determine initial attitude towards communism Likert Scale Read pro- and anti-communism passages Students 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 learning 34

35 Subsequent Learning (Interference) Inactivity during retention interval leads to less forgetting than activity Implies forgetting partly based on learning new material Jenkins & Dallenbach (1924) Recall (%) Hours after learning tested sleep awake 35

36 Retroactive Interference New learning interferes with ability to recall earlier learning PAL technique (opposite order) Subjects learn A-C, but some then learn A-B Test by giving A and recalling C Subjects who learned A-B have worse recall for C e.g. forgetting old phone numbers, license plates, passwords 36

37 PAL example BOTH groups first learn: Red-Apple Cloud-Shoe Cat-Shelf Plate-Spoon Carpet-Tent 1 group then learns: Red-Book Cloud-Paper Cat-Fence Plate-Notebook Carpet-Window 37 Both groups then RECALL: Red- ________ Cloud- ________ Cat- ________ Plate- ________ Carpet- ________ Order is just “switched” from last example

38 Context Learning occurs in a context Various stimuli around the learner These stimuli serve as cues to evoke a behaviour If stimuli absent, may have cue-dependent forgetting Stimulus control e.g. forgetting names when in a different context 38

39 Context 39 SDSD Colour, size, shape, etc… Cue set, set of S D ’s, has changed! Less cues to signal correct response.

40 Perkins & Weyant (1958) Train two groups of rats in two mazes, one black, one white 1 minute retention interval Half of each group tested in original maze, half in maze of opposite colour Opposite colour rats did poorly compared to original maze tested rats 40

41 Kamin (1957) Gave rats avoidance learning, tested at various retention intervals. Time of day, internal clock Internal physiological state cues recall “internal” context Avoidance (%) Retention Interval (hr)

42 State-Dependent Learning Train under a particular physiological state (e.g., drug condition) and test under various states Recall best when in the same state as training Drug conditions: alcohol, caffeine, etc. Internal State: tired, level of stress, emotions, etc. 42

43 Application: Foraging Food Caching Cache: food store Retrieval of food later Spatial memory Wide variety of species Accuracy can be quite high for very long times 43

44 Application: Eyewitness Testimony Notoriously poor Basic issue of retention interval and forgetting Also the nature of the question used to retrieve information 44

45 Loftus & Zanni (1975) Subjects watched film of car accident Asked “Did you see / broken headlight?” “the” subjects twice as likely as “a” subjects to say “yes” Actually, no broken headlight shown Reinforcement history Previous conditioning: “the” (definite article) implies presence; “a” implies possible presence 45

46 Loftus & Palmer (1974) Watch film of car accident “How fast were the cars going when they hit each other?” Underlined word replaced with smashed, collided, bumped, contacted Speed estimates varied based on wording of question Reports of broken glass varied based on wording 46

47 47

48 Learning to Remember In essence, improving learning Practice increases retention Techniques: Overlearning Mnemonics Context cues Prompts 48

49 Overlearning Practice beyond learning e.g. Tiger Woods putting practice e.g. Flash Cards (SAFMEDS) 49

50 Mnemonics Rhymes, First Letters HOMES, Roy G. Biv Method of Loci Associate learned items with locations on a well-known route Peg Word System 1 = “bun”, 2 = “shoe”, 3 = “tree”… Also works with visual 1 looks like a pencil, 2 looks like a swan, 3 is a tricycle… 50

51 Mnemonic example 1 – “coffee cup” – imagine using a coffee cup as a pencil holder 2 – “rubber ball” – imagine a swan holding a rubber ball in its beak 3 – “printer” – imagine a printer printing a piece of paper with a tricycle on it 4 – “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) 51

52 Context Cues Keep context the same Study in classroom Pay attention to habits, internal states 52

53 Prompts Creating S+’s Memos, notes, calendar markings Often don’t contain all info, so just a “reminder” of what needs to be done E.g. “3-Choice meeting” String on finger, watch beep, cell phone reminders 53


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