Exploring Memory: Types, Forgetting, and Measurement Techniques

1. Chapter 11 Forgetting

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

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

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

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

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

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

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

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

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

11. Prompted (Cued) Recall • Give prompts to increase likelihood of behaviour • Measure number of prompts needed to produce behaviour

12. Cued Recall: • Recall: • Ba_________ • In_________ • An_________ • Bo_________ • Co_________ • 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

14. Relearning Trial #1 Trial #2 Trial #3 • Learn : • Banana • Interesting • Annoy • Book • Computer • Recall: • Banana • __________ • Annoy • __________ • __________ • Recall: • Banana • __________ • Annoy • Book • __________ • Recall: • Banana • Interesting • Annoy • Book • Computer Score = 2/5 Total Trials on Initial Learning = 3 Score = 3/5 Score = 5/5 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

16. Recognition • Which words were on the list? • Banana • Orange • Interesting • Annoy • Ugly • Computer • Table • Apple • 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

18. Extinction Method • Train two 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

19. Extinction methods Group 1 & 2 Learning Phase Group 1 Extinction Group 2 Extinction break 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

21. Gradient degradation No Forgetting Training: Establish gradient Forgetting

22. Variables in Forgetting

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

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

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 is twice as good as 50% overlearning

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

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%

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)

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?

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

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

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

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 • 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

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) 100 50 sleep Recall (%) awake 0 2 4 6 8 Hours after learning tested

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

37. PAL example • BOTH groups first learns: • Red-Apple • Cloud-Shoe • Cat-Shelf • Plate-Spoon • Carpet-Tent • 1 group then learns: • Red-Book • Cloud-Paper • Cat-Fence • Plate-Notebook • Carpet-Window • 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

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

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

41. 100 50 Avoidance (%) 0 12 24 36 48 60 72 84 Retention Interval (hr) Kamin (1957) • Gave rats avoidance learning, tested at various retention intervals. • Time of day, internal clock • Internal physiological state cues recall • “internal” context

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.

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

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

45. Loftus & Zanni (1975) • Subjects watched film of car accident • Asked “Did you see <the>/<a> 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

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

47. Learning to Remember

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

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

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…