PSY 368 Human Memory

1. PSY 368 Human Memory Memory Implicit memory

2. Outline • Implicit versus explicit memory • Definitions • Dissociations • Process-dissociation procedure • Theories accounting for Implicit vs. Explicit memory

3. Demo • PDP exercise • Pass out sheets and read instructions • Collecting the data: count up number of study words that were written down for each task, write this on your sheet

4. Questions to Think About • Does the type of memory test matter? • We’ve seen that the answer is yes. So far have covered intentional vs. incidental, and recall vs. recognition. These have largely been what are considered direct tests of memory (know that it is a memory test related to something earlier). • There are also indirect tests of memory (don’t know that the test is related to memory/to something done earlier)

5. Memory Tasks Test Instructions • Also “Non-declarative” & “procedural” (Squire, Knowlton, & Mesen, 1993) Study Instructions Implicit Memory: Often defined as "memory without awareness”

6. Implicit Memory Tasks Often defined as "memory without awareness” Perceptual Tasks Word identification Word stem completion Word fragment completion Degraded word naming Anagram solution Lexical decision Non-Verbal Tasks Picture fragment naming Object decision task Possible/impossible object decision Conceptual Tasks Word association Category instance generation Answering general knowledge questions

7. Implicit Memory Tasks Often defined as "memory without awareness” Perceptual Tasks Word identification Word stem completion Word fragment completion Degraded word naming Anagram solution Lexical decision Non-Verbal Tasks Picture fragment naming Object decision task Possible/impossible object decision Conceptual Tasks Word association Category instance generation Answering general knowledge questions

8. Implicit Memory Tasks Examples • Study: bird, house, balloon, horse, rocket, dolphin • (maybe levels of processing, or divided attention manipulation) • Tests: • Lexical decision – bronk ‘no’ - - horse ‘yes’ -- … • Stem Completion - hor- “horde” vs “horse” • Fragment Completion - h_r_s_ “hares” vs “horse” • Category exemplar production - Animal-? “pig” vs “horse” • Word Association - saddle - ? “leather”“bags”“horse”

9. Implicit Memory Tasks Examples • Study: bird, house, balloon, horse, rocket, dolphin • (maybe levels of processing, or divided attention manipulation) • Tests: • Picture fragment naming

10. Do amnesics have memory? • Warrington and Weiskrantz (1968, 1970, 1974) showed differences in memory performance for amnesic patients • Amnesic patients • Can’t complete typical explicit memory tasks • Typically don’t even remember seeing a list • Performance on implicit tasks is similar to control participants

11. Explicit vs. Implicit Memory • The Search for Dissociations • Suggests that these tasks rely on different forms of memory • Dissociation = different effects of an IV on the two test types (similar to the recognition vs. recall dissociations)

12. Explicit vs. Implicit Memory Jacoby (1983): Generation Effect • Study tasks • Read aloud w/o context • COLD • Read w/ context • hot – COLD • Generate from context • hot - ??? • Test tasks • Recognition • Perceptual Identification Opposite pattern of results with implicit task

13. Explicit vs. Implicit Memory Roediger& Weldon, (1987) • Study tasks • Lists of pictures and words • Test tasks • Free recall of pictures and words • Word fragment completion • Priming effect: compared studied vs. unstudied completions

14. Explicit vs. Implicit Memory Rajarm, Srinivas, & Travers (2001) Attention Effect • Study • Full attention • read word as quickly as possible • Divided attention • Name the color the word is presented in • Test • Word stem completion • 2 instructions • Use words from earlier list • First word you think of

15. Explicit vs. Implicit Memory • Study • List of words Tulving, Schacter, & Stark (1982): Forgetting Effects • Test • Word fragment completion • After 1 hr. & 7 days later • Memory score = priming effect • Compare fragment completions of old vs. new items

16. Mixing Measures • Tasks are not “process pure” (Jacoby, 1991) • Indirect measures of memory may be “contaminated” by intentional uses of memory • E.g., in stem completion task, subjects might remember items from previous list and use them to complete the stems • Direct measures may be influenced by unconscious or automatic influences (Jacoby, Toth, & Yonelinas, 1993) • Process-Dissociation Procedure was developed to separate automatic (unconscious) and conscious processes

17. Process Dissociation Procedure Jacoby (1991) • Read a list of words – List 1 • Hear a list of words – List 2 • Two recognition tests: • Both tests include List 1, List 2 and novel words. • Inclusion = complete task with studied or any item • Respond “old” if word was on either list. • Exclusion = complete task with item NOT studied (exclude studied items) • Respond “old”only if word was on List 2.

18. Process Dissociation Procedure Jacoby (1991) • Can calculate C and A for each condition in the experiment • C = (Proportion of studied items in inclusion) - (Proportion of studied items in exclusion) • A = (Proportion of studied items in exclusion) / (1-C) • The C and A values are estimated as proportions - values between 0 and 1.0 • Data • Proportion of studied items in inclusion = C + (1-C)(A) • Proportion of studied items in exclusion = (1-C)(A)

19. Process Dissociation Procedure Jacoby (1991) • Exclusion: Respond “old”only if word was on List 2. • Use equations to calculate conscious (C) and automatic (A) memory from target performance on the tasks • P(old) = A(1-C) • Subject will only respond “old” to List 1 words if two things happen: • A: The automatic process responds “old” due to a feeling of familiarity • (1-C): The intentional process fails to recognise the word (if it had, it would recall it was from List 1)

20. Process Dissociation Procedure Jacoby (1991) • Inclusion: Respond “old” if word was on either list. • Use equations to calculate conscious (C) and automatic (A) memory from target performance on the tasks • P(old) = C + A (1-C) • If either process concludes “old”, the subject will respond “old” • A: Automatic process will also have a certain probability of concluding “old” for List 1 words • C: Conscious (intentional) process will have a certain probability of concluding “old” for List 1 words

21. Process Dissociation Procedure Jacoby (1991) • Read a list of words – List 1 • Hear a list of words – List 2 • Inclusion = Respond “old” if word was on either list. • Exclusion = Respond “old”only if word was on List 2. • Inclusion test P(old) = 0.48 • Exclusion test P(old) = 0.37* • C = Inclusion – Exclusion = 0.11 • A = Exclusion / (1-C) = 0.37 / 0.89 = 0.42 • *in exclusion condition, “OLD” are errors

22. Process Dissociation Procedure Jacoby, Toth, & Yolelinas (1993): Attentional effects • Study: read words • full attention • divided attention – read aloud while listening for odd numbers • Task: stem completion: • inclusion: complete with list word or guess • green stem inclusion (may use as a cue from list) • exclusion: complete with new words only • red stemexclusion (complete with word not from list)

23. Process Dissociation Procedure Jacoby, Toth, & Yolelinas (1993) (Exp 1b) Divided attention: • Inclusion task:  P(old) • Exclusion task:  P(old) • Results: • Inclusion: div (46%) < full (61%) • Exclusion: div (46%) > full (36%) • Interpretation: • div attention knocked out recollection • recollection  accuracy in both conditions

24. Process Dissociation Procedure Jacoby, Toth, & Yolelinas (1993) (Exp 1b) Conclusions • Conscious recollection greatly reduced under divided attention condition

25. Process Dissociation Procedure Toth, Reingold, and Jacoby (1994): Levels of Processing Study • Pleasantness rating • Shared vowels Test • Stem completion task Study • Read word • Say aloud missing word in sentence Test • Stem completion task

26. Accounting for Implicit and Explicit Effects • Four major approaches have been proposed • The Activation view • Multiple Memory systems view • Transfer appropriate processing view • Bias View • STOP HERE FOR TODAY

27. Activation view • Insert slide here

28. Memory Systems • Many believe there are different systems of memory • What is a system? • Could involve different brain areas (amnesia) • Could involve different rates of forgetting

29. Memory Systems Squire (1987)

30. Memory Systems Squire (1987)

31. Memory Systems • Brain areas • Brain imaging studies found that different areas of the brain are used when completing implicit and explicit tasks • But there isn’t just one structure involved in each type of memory • And different kinds of implicit tasks seem to involve different areas • Conclusion: brain area involvement may be a function of type of processing and type of memory

32. Memory Systems • Forgetting • Tulving et al. (1989) showed a difference in forgetting rate for recognition and fragment completion • Confirmed with other tasks (stem completion)

33. Memory Systems • Forgetting • But these studies looked at long-term forgetting (days, months) • Didn’t follow RIC or use PDP

34. Memory Systems • Forgetting • More recent studies showed no difference in forgetting rates for implicit/explicit stem completion • Used RIC and PDP

35. Memory Systems

36. Memory Systems

37. Mixing Implicit and Explicit Effects • Jacoby (1990) proposed that implicit vs. explicit memory is confounded with two different kinds of memory processes (associated with two kinds of information)

38. Processing View • Based on TAP view • Tasks used for implicit memory usually have perceptual cues • app- • a_p_l_ • Explicit tasks often are more conceptual

39. Processing View • Differences found between implicit/explicit tasks could reflect perceptual/conceptual differences • Tested by Blaxton (1989)

40. Processing View

41. Processing View

42. Processing View • Read/Generate study • Compared tasks across both dimensions

44. Processing View • Shows that match between study and test processing is more important • Weldon & Roediger (1987) found different picture superiority effect for two implicit tasks

45. Summary of Implicit/Explicit • TAP may be more important than memory process • Implicit and explicit tasks are not “process pure” • PDP offers a measurement method for processes • Implicit/Explicit memory show dissociations on several variables

46. Explicit vs. Implicit memory • Generation effect (Java, 1993) - found for explicit but reversed for implicit • Subjects studied words - read or generated • Completed implicit and explicit stem completion

47. Explicit vs. Implicit memory • Level of Processing (Roediger et al., 1992) - found for explicit but not implicit • Subjects studied words - pleasantness vs. letter tasks • Completed implicit and explicit stem and fragment completion

48. Explicit vs. Implicit memory • Attention (Mulligan, 1998) - dividing attention at study reduces explicit not implicit • Study - just study words vs. study words and do extra task • Test - implicit/explicit fragment completion

49. Explicit vs. Implicit memory • Forgetting (Tulving, Schacter, & Stark, 1982) - difference in forgetting rates for explicit/implicit task performance • Looked at performance for recognition and implicit fragment completion at 1 hr and 2 days • Recognition performance declined, but implicit task performance did not

50. Processing View • Studied pictures and words • Tested with picture fragment naming and word fragment completion • Picture fragment naming = name degraded picture with first thing it looks like