- Leonard Läer - Philipp Schleenvoigt - Ulrich Süß

1. Presentation on“On the Reliability of Implicit and Explicit Memory Measures” by Axel Buchner and Werner Wippich - Leonard Läer - Philipp Schleenvoigt - Ulrich Süß by

2. ON THE RELIABILITY OF EXPLICIT AND IMPLICIT MEMORY MEASURES - TABLE OF CONTENTS • Table of Contents • PART I - INTRODUCTION • Main statement of the article • What is this reliability thing, anyway? • The role of reliability of memory tests • Reasons for reliability differences between memory measures • PART II - THE EXPERIMENTS • Experiment 1a • Experiment 1b • Experiment 2 • Experiment 3 • PART III - CONCLUSIONS

3. ON THE RELIABILITY OF EXPLICIT AND IMPLICIT MEMORY MEASURES - INTRODUCTION • PART I - INTRODUCTION • MAIN STATEMENT OF THE ARTICLE • former tests seemed to reveal functional dissociations between explicit and implicit memory: • older subjects (amnesic / distracted) perform worse than younger (“normal” / undistracted) subjects in explicit memory tests, but nearly equal in implicit memory tests • but: same results possible if the reliability of the explicit memory tests were better than that of the implicit ones! • do our “found” dissociations only occur due to methodological reasons?

4. ON THE RELIABILITY OF EXPLICIT AND IMPLICIT MEMORY MEASURES - INTRODUCTION • WHAT IS THIS RELIABILITY THING, ANYWAY? • in classical test theory we have: • a true score of some feature we want to measure • an observed score of that feature • ameasurement error • the higher the error variance, the worse is the correlation between the true score and the observed score • a test with a lower error variance is thus more reliable • reliability is the strength of the relation between observed and true score

5. ON THE RELIABILITY OF EXPLICIT AND IMPLICIT MEMORY MEASURES - INTRODUCTION • THE ROLE OF RELIABILITY OF MEMORY TESTS • testing groups that vary in their memory abilities, we should expect: • to find larger differences in observed scores when using highly reliable tests • to find lower differences in observed scores when using badly reliable tests • assuming we use equally reliable tests for explicit and implicit memory, the same results (large difference for one, low difference for the other “system”) would have been to be interpreted as a functional dissociation between these two systems • however, assuming our tests for explicit memory are more reliable than those for implicit memory, we have to consider the possibility that there is no functional, but a methodological reason for these results

6. ON THE RELIABILITY OF EXPLICIT AND IMPLICIT MEMORY MEASURES - INTRODUCTION • REASONS FOR RELIABILTY DIFFERENCES IN MEMORY MEASURES • reliability differences in memory tests due to: • differences in instructions • rigidity of goals • possible strategies to achieve solution • usual implicit memory tests: • many possible solution strategies • loosely defined goals • usual explicit memory tests: • few possible solution strategies • clearly defined goals

7. ON THE RELIABILITY OF EXPLICIT AND IMPLICIT MEMORY MEASURES - THE EXPERIMENTS • PART II - THE EXPERIMENTS • 1. experiment that typically leads to the dissociation assumption • learning phase: • two groups of participants (n=42 each) • list of 92 nouns • each noun appeared for four seconds on screen

8. ON THE RELIABILITY OF EXPLICIT AND IMPLICIT MEMORY MEASURES - THE EXPERIMENTS • one hour break... • test phase: • explicit memory group: word recognition (yes/no) • “decide whether the noun appeared in the list.” • implicit memory group: word-stem completion (priming score) • “form any regular word from the following word -stems.”

9. ON THE RELIABILITY OF EXPLICIT AND IMPLICIT MEMORY MEASURES - THE EXPERIMENTS results: hit-rate split-half correlation ( reliability) word recognition 77% 88 word-stem completion 12% 35

10. ON THE RELIABILITY OF EXPLICIT AND IMPLICIT MEMORY MEASURES - THE EXPERIMENTS • 2. experiment confirms assumption about reliability • learning phase: • one group of participants (n=42 each) • list of 92 nouns • each noun appeared for four seconds on screen

11. ON THE RELIABILITY OF EXPLICIT AND IMPLICIT MEMORY MEASURES - THE EXPERIMENTS • one hour break... • test phase: • explicit memory group: word-stem cued recall (priming score) • “form words that appeared in the list from the following word-stems.”

12. ON THE RELIABILITY OF EXPLICIT AND IMPLICIT MEMORY MEASURES - THE EXPERIMENTS results: hit-rate split-half correlation ( reliability) word recognition 77% .88 word-stem completion 12% .35 word-stem cued recall 62% .75

13. ON THE RELIABILITY OF EXPLICIT AND IMPLICIT MEMORY MEASURES - THE EXPERIMENTS • discussion: • explicit memory measures seem to have generally higher reliability than implicit memory measures. • assumption: degree of reliability depends on the sum of • - the number of possible strategies leading to solution: • implicit memory strategies are numerous like completing word-stems by reference to their graphemic-, phonological-, etc. properties. • explicit memory strategies are less numerous due to more precised instructions. • - the number of possible solutions: • implicit memory tasks like free association normally do have many possible solutions. • explicit memory tasks like word recognition do have a minor number of possible solutions (eg. yes / no).

14. ON THE RELIABILITY OF EXPLICIT AND IMPLICIT MEMORY MEASURES - THE EXPERIMENTS there is light at the end of the tunnel... let’s try to equalize the reliabilities of the two (implicit/explicit) memory tests use more restrictive instructions! eg.: provide search strategy (eg. “try to find the solution quickly.”), thus decreasing the number of strategies.

15. ON THE RELIABILITY OF EXPLICIT AND IMPLICIT MEMORY MEASURES - THE EXPERIMENTS • 3. experiment equals reliabilities • learning phase: • two groups of participants (n=32 each) • list of 50 pictures • “name each picture appearing on screen as quickly as a possible.”

16. ON THE RELIABILITY OF EXPLICIT AND IMPLICIT MEMORY MEASURES - THE EXPERIMENTS • test phase: • explicit memory group: picture recognition (yes/no) • “decide whether the picture appeared in the list.” • implicit memory group: fragmented picture identification (priming score) • “identify picture as quickly as possible and with a minimal number of steps in the defragmentation procedure.”

17. ON THE RELIABILITY OF EXPLICIT AND IMPLICIT MEMORY MEASURES - THE EXPERIMENTS results: hit-rate split-half correlation ( reliability) word recognition 77% .88 word-stem completion 12% .35 picture recognition 90% .41 picture identification 115% .44

18. ON THE RELIABILITY OF EXPLICIT AND IMPLICIT MEMORY MEASURES - THE EXPERIMENTS conclusion: these results are compatible with the hypothesis that the reliability of the measures derived from implicit memory tests need not necessarily be smaller than that of the measures derived from explicit memory tests. rather, implicit memory measures may be at least as reliable as explicit memory measures, provided that the testsituation implied by the implicit memory tests is restrictive enough.

19. ON THE RELIABILITY OF EXPLICIT AND IMPLICIT MEMORY MEASURES - THE EXPERIMENTS general discussion: should one neglect the dissociation theory because of this results? no, but the problem we face here seems serious. so, the problem can only be reduced to the degree to which highly reliable implicit memory measures are used in conjunction with sufficiently large sample sizes.