PSY 368 Human Memory

1. PSY 368 Human Memory Memory Implicit memory

2. Outline • Theories accounting for Implicit vs. Explicit memory • Experiment 2 Signal detection analysis • Process-dissociation procedure, working through our example (probably not time, so after break)

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

4. Implicit/Explicit Dissociations • Many demonstrations of different effects depending on whether implicit or explicit tasks are used • Amnesic patients • Levels of processing manipulations • Pleasantness vs. vowel comparisons • Generation effect • Divided attention • Picture-word superiority • Note. Most of we’ve talked about concern repetition priming effect (study “horse” and respond “horse”)

5. Accounting for Implicit/Explicit Dissociations • Four major approaches have been proposed • The Activation view • Multiple Memory systems view • Transfer appropriate processing view • Bias View

6. Accounting for Implicit/Explicit Dissociations • Four major approaches have been proposed • The Activation view • Multiple Memory systems view • Transfer appropriate processing view • Bias View

7. The Activation View • Priming on indirect tests is attributable to the temporary automatic activation of preexisting representations. • Because it is automatic, it occurs without elaborative processing and thus has little to no contextual information • Weak Point • Can not explain priming over long time periods • Some implicit priming over days or even weeks (e.g., Sloman, et al, 1988) • Can not explain priming without pre-existing representations • The least popular of the four views

8. Accounting for Implicit/Explicit Dissociations • Four major approaches have been proposed • The Activation view • Multiple Memory systems view • Transfer appropriate processing view • Bias View

9. Multiple Memory Systems • Many dissociations between direct and indirect tests of memory arise because the tests tap different underlying memory systems. Squire (1987)

10. Multiple Memory Systems • Many dissociations between direct and indirect tests of memory arise because the tests tap different underlying memory systems. Tulving (1984)

11. Multiple Memory Systems • What is a system? • It is NOT a process • It is NOT a task • Some different ways that systems have been defined • Schacter and Tulving (1994)

12. Multiple Memory Systems • What is a system? • Functional Dissociations • Task that taps into system A that has no effect (or a different effect) in System B • Different neural substrates • System A involves different brain areas than System B (brain damage cases and neural imaging studies) • Stochastic independence • Performance on System A task uncorrelated with performance on a System B task • Functional incompatibility • Could involve different rates of forgetting • Function carried out by System A can not be done by System B • Schacter and Tulving (1994)

13. Multiple Memory Systems • What is a system? • Schacter and Tulving (1994) If you “know how to do something” Allows you to automatically recognize things See earlier in the semester Factual information (chpt 10) Memory of events

14. Multiple Memory Systems Buckner et al (1995) PET study • Brain areas • Brain imaging studies found that different areas of the brain are used when completing implicit and explicit tasks • Note: more than one structure involved in each type of memory

15. Multiple Memory Systems Gabrieli et al (1995) Case study of MS • Studied lists of words • Perceptual identification and recognition task • Brain areas • Brain imaging studies found that different areas of the brain are used when completing implicit and explicit tasks • Intact performance on explicit tests of recognition and cued recall • Intact performance on implicit test of conceptual memory • Impaired performance on implicit tests of visual perceptual memory MRI of MS’s brain • Suggests a specific deficit in visual implicit memory

16. Multiple Memory Systems Buckner & Koutstall (1998) fMRI study • Brain areas • Different kinds of implicit tasks seem to involve different areas • Perceptual vs. conceptual tasks appear to use different brain areas • Conclusion: brain area involvement may be a function of type of processing and type of memory

17. Multiple Memory Systems • Stochastic Independence • Hayman and Tulving (1989) • Measure correlation between explicit and implicit task performance • If not correlated (independent), then tasks measure different processes • Forgetting • Tulving et al. (1989) showed a difference in forgetting rate for recognition and fragment completion • Confirmed with other tasks (stem completion)

18. Multiple Memory Systems • Strengths • Fits well with dissociations found • In patients • In experiments • Problem • Hard to find consensus on what the systems are • May be “too easy” to posit a new system

19. Accounting for Implicit/Explicit Dissociations • Four major approaches have been proposed • The Activation view • Multiple Memory systems view • Transfer appropriate processing view • Bias View

20. Transfer Appropriate Process • The key to good performance is similarity of processes involved in encoding vs. retrieval, be it implicit or explicit, perceptual or conceptual test • Implicit and explicit may refer to different processes, yet the key to performance is matching processes. A consequence: conceptual processing is the common core in free recall and implicit conceptual tasks, hence performance on these two types of task should be equal. Overlap determines retrieval success Processes at encoding Processes at test

21. Transfer Appropriate Process Assumes: • Performance depends of match between processing at study and processing at test. Analogous to encoding specificity. • Two-types of Processes (Jacoby, 1990) • Data-driven (perceptual) – processing of physical features. • Conceptually-driven (semantic) – processing for meaning Typically confounded, however, it is possible to un-confound test-type from process-type

22. 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)

23. Data-driven (Perceptual): fragment completion stem completion anagram completion lexical decision perceptual identification Conceptually-driven (Semantic): word association doctor  ?? category-instance generation “name a mammal” general knowledge “The capital of the US is …?” Transfer Appropriate Process

24. Transfer Appropriate Process Blaxton (1989) • Goal to demonstrate • data-driven processing can affect direct tests • data-driven processing do not necessarily affect indirect tests

25. Transfer Appropriate Process Blaxton (1989) S’s saw or heard lists of words (key IV here) Target word: bashful • graphic-cued recall: looks like “bushful” • free recall • frag completion: b_sh_u_ • General knowledge: “Name one of the 7 dwarfs”

26. Transfer Appropriate Process Blaxton (1989) Predictions • Systems view: modality match should affect only indirect tests (if indirect tap separate system, then modality should affect them in the same way) • for both implicit tests: visual > auditory • for both explicit test: visual = auditory Same pattern of results regardless of modality Visual better than auditory for both

27. Transfer Appropriate Process Blaxton (1989) Predictions • TAP View: modality match should affect data-driven tasks only. (priming depends on match between study/test processing match & not on indirect vs direct): • for both data-driven tests: visual > auditory • for both conceptually-driven tests: visual = auditory Visual should be better than auditory Visual and auditory should be about the same

28. Transfer Appropriate Process Blaxton (1989) Results Priming Effect (V > A) for data-driven tasks only: • indirect: frag completion • direct: graphemic-cued recall Not all indirect tests display priming effect. • Gen Know (indirect, conceptual): V = A • Conclusions • Support view that processing rather than system is what is important

29. Accounting for Implicit/Explicit Dissociations • Four major approaches have been proposed • The Activation view • Multiple Memory systems view • Transfer appropriate processing view • Bias View

30. The Bias View • Proposed to account for repetition priming effects. • Prior presentation of an item can bias subsequent processing of the item on later presentations (if you see it once, you are more likely to interpret in the same way later) • Multiple systems attributes this to 3 separate systems, but doesn’t really offer an explanation • TAP’s answer is considered circular (you respond faster the second time because of transfer appropriate processing, which was developed to account for priming effects)

31. The Bias View • Bias View’s account for repetition priming effects. • Bias entails both cost and benefits • Cost : There will be an advantage if prior processing is appropriate for the current task • Benefits : There will be a disadvantage if prior processing is inappropriate for the current task 2. Second See ambiguous woman 3. People are more likely to interpret the ambiguous picture as the same person as the unambiguous picture 1. First See one of old woman and young woman

32. Comparing the theories TAP Multiple Systmes • Strengths • Processing perspective • No “need” for separate systems (true of Bias view too) • Bias View may be seen as a complement to the TAP view • Weaknesses • Doesn’t explain impact of conscious awareness • Trouble with finer grain distinctions between tasks • Strengths • Good fit for deficit data (but may be too easy to propose “new systems”) • Weaknesses • Has troubles with some data showing differential decline in memory performance with aging • Sometimes difficult to make specific predictions in advance

33. Implicit Memory Summary • Implicit memory is memory without awareness. • Implicit and explicit tasks are not “process pure” • PDP offers a measurement method for processes • Implicit memory is different memory from explicit memory by experimental dissociations. • There is 4 main accounts for implicit memory • Probably a complex relationship between systems and processes

34. Experiment 2 • Recall that for experiment 2 you each collected data from three participants. • IV – levels • Prediction: our instructions would lead participants to shift their criterion for what counts as old vs. new. • Signal detection analysis

35. Signal Detection Theory • Recognition accuracy depends on: • Whether a signal (noise/target memory) was actually presented • The participant’s response • Thus, there are four possible outcomes: • Hits • Correctly reporting the presence of the signal • Correct Rejections • Correctly reporting the absence of the signal • False Alarms • Incorrectly reporting presence of the signal when it did not occur • Misses • Failing to report the presence of the signal when it occurred CORRECT INCORRECT

36. Signal Detection Theory • Calculating d’ and C (or β) • Discriminability (d’): • Step 1) Look up the z-score for the average Hit and False Alarm rates. • Step 2) Apply the formula d’ = zHIT – zFA, where zFA is the z-score for FAs and zHIT is the z-score for Hits. • Criteria C (or β): • Take the negative of the average of zHIT and zFA. This is the criterion value C. • Remember that positive C values indicate a conservative response bias, while negative C values indicate a liberal response bias. http://memory.psych.mun.ca/models/dprime/

37. Experiment 2 N=21 per condition Neutral Total possible hits or false alarms = 20 Conservative Averages Proportions (avg/20) Liberal

38. Experiment 2 http://memory.psych.mun.ca/models/dprime/ d’ = 1.85 C = 0.25 Neutral d’ = 1.81 C = 0.65 Conservative d’ = 1.81 C = -0.13 Liberal

39. Experiment 2 d’ Neutral d’ = 1.85 C = 0.25 Conservative d’ = 1.81 C = 0.65 Signal (remember) probability Liberal Noise d’ = 1.81 C = -0.13 stimulus intensity

40. Experiment 2 - Criterion + Neutral d’ = 1.85 C = 0.25 New Old Conservative d’ = 1.81 C = 0.65 Signal (remember) probability Liberal Noise d’ = 1.81 C = -0.13 stimulus intensity

41. Experiment 2 - Criterion + Neutral d’ = 1.85 C = 0.25 New Old Signal (remember) probability Noise stimulus intensity

42. Experiment 2 - Criterion + New Old Conservative d’ = 1.81 C = 0.65 Signal (remember) probability Noise stimulus intensity

43. Experiment 2 - Criterion + New Old Signal (remember) probability Liberal Noise d’ = 1.81 C = -0.13 stimulus intensity