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					Hypermnesia: Why does memory
  improve over repeated tests?
   Hajime Otani, Central Michigan
             University
  Robert L. Widner, Jr., University of
    Colorado at Colorado Springs
       What is hypermnesia?
• Improvement in memory performance over
  repeated testing.
• Erdelyi and Becker (1974)
  – Presented a mixed list of words and pictures
  – Administered three tests - T1 T2 T3
  – Found - memory improved over three tests for
    pictures but not for words.
  – Important - The stimulus materials were not
    presented between tests.
            Big Question
• How does memory improve over repeated
  test?
               Interesting
• Counter-intuitive based on Ebbinghaus’
  forgetting curve.
• Test 1 should show the best performance.
 So, why does memory improve?
• Erdelyi and colleagues
  – “Imagery hypothesis”
  – Memory improves only when the materials are
    encoded as “pictorial images.”
  – Erdelyi and Becker (1974) and others -
    hypermnesia occurs only when pictures or
    words with imagery instructions are used.
  But, soon people discovered...
• Hypermnesia occurs without pictures or
  words with imagery instructions.
• Good example - Roedgier, Payne, Gillespie,
  & Lean (1982) Exp. 2
  – used nonsense syllables.
             New hypothesis
• Roediger et al (1982)
  – “Cumulative recall level hypothesis”
  – Hypermnesia occurs when performance on the
    first test does not reach asymptote.
  – Prediction - the higher the asymptote, the
    greater the hypermnesic effect, because it takes
    more time to reach higher asymptote.
• Studies generally have supported this.
                 But……
• This is not complete - Roediger and Challis
  (1989)
• This is only a functional account. So, how
  does performance increase toward the
  asymptotic performance?
• It considers only one component of
  hypermnesia.
                   In fact….
• Two components of hypermnesia.
  – Reminiscence (item gain) - retrieval of new
    items.
  – Inter-test forgetting (item loss) - forgetting of
    previously recalled items.
• So, on the second test
  – Gain = 20 items (wow!)
  – But, if you lose 20 items or more, performance
    does not increase.
           But, to be fair….
• It is common to find similar forgetting
  across conditions.
• But still, you cannot “forget” this
  component.
            Good example...
• Payne (1986)
  – equated the asymptotic performance of pictures
    and words.
  – Prediction - this should equate the amount of
    hypermnesia.
  – Wrong - Pictures still showed better
    hypermnesia.
  – Why? - less inter-test forgetting
       So, how do you explain
            hypermnesia?
• My approach - use different retrieval tests.
• Assumption - different tests require
  different processing.
• Others were already testing hypermnesia
  using different tests.
• Also, manipulate the encoding strategies.
  Because processing at encoding may
  interact with processing at retrieval.
               My selection
• Retrieval tests
  – Recognition & Cued recall
• Encoding strategies
  – Relational and item-specific processing (Hunt
    & colleagues)
  – Relational - relate items together. Create
    organization.
  – Item-specific - make each item distinctive.
   My selection was based on...
• Recognition - others tried and failed.
• Cued recall - prediction was negative.
• Relational & item-specific processing -
  Hunt and colleagues were trying to explain
  recall and recognition using these notions.
            How did it go?
• Recognition - No luck what-so-ever.
  – Otani & Hodge (1991)
  – Otani & Stimson (1994)
                 Cued recall
• Turned out to be somewhat interesting
• Otani & Hodge (1991) Experiment 2
  – Presented with 36 word pairs - cue - target
  – Categorized list - targets belong to 6 categories.
  – Relational - Sort the targets into categories.
  – Item-specific - Rate the pleasantness of the
    targets.
  – Three cued recall test - 7 minutes each.
               Results….
• Relational - hypermnesia
• Item-specific - no hypermnesia
• Intentional - no hypermnesia
• The difference - Greater reminiscence in the
  relational condition.
• Only marginally significant difference in
  forgetting.
                  But….
• Performance was much lower in the
  relational condition.
• So, we decided to use a loosely categorized
  list (no obvious categories).
• Prediction - The use of such a list would
  reduce the hypermnesic effect.
                 Results
• No overall difference in performance.
• There was a slight improvement in the item-
  specific processing condition.
• But, the greatest improvement occurred in
  the relational processing condition.
• Reason - Greater reminiscence.
• No difference in inter-test forgetting.
                Why is it?
• My initial reaction was - the category labels
  created extra retrieval cues.
• E.g., “So, what was it?” “It was a fruit, red
  one maybe…” “I got it.” “It was apple.”
• Similar to Roediger and colleagues’ idea.
  Elaborated by Payne, Hembrooke, &
           Anasatasi, (1993)
• Two mechanisms based on the SAM model.
  – Incrementing - memory trace and its
    connections to other items become stronger and
    retrieval becomes faster.
  – Alternative retrieval routes - use different
    retrieval paths to find new items.
 Otani, Widner, Whiteman, & St. Louis
               (in press)
• Tested the alternative retrieval routes
  hypothesis.
• Approach - give participants more than one
  retrieval cue.
               Experiment 1
• Presented 36 word pairs - cue - target
• Single cue condition - no additional cues.
  – E.g., war - bomb
• Multiple cue given - two additional cues.
  – E.g, war, kill, loud - bomb
• Multiple cue Generate - Asked to generate
  two additional cues
  – E.g., war, ___, ____, - bomb
• Three cued recall tests - 7 minutes each
• Presented only one cue for all the
  conditions.
  – E.g., war - ______
• Assumption - Participants would use
  additional cues to retrieve previously
  unretrieved items.
                 Results
• Performance improved for both the multiple
  cue given and multiple cue generate
  conditions.
• No improvement for the single cue
  condition.
• Reason - Greater reminiscence.
• No difference in inter-test forgetting.
                Experiment 2
•   Did they really use the additional cues?
•   Made extra cues explicit at retrieval.
•   Presented 60 word pairs.
•   Three cued recall tests - 7 minutes each.
• Three conditions
  – Single - Single - single cue at study and single
    cue at test.
  – Multiple - Single - multiple cue at study and
    single cue at test.
  – Multiple - Multiple - multiple cue at study and
    multiple cue at test.
                  Results
• Performance improved for all conditions.
• Reason - categorized list.
• But, improvement was greatest in the
  multiple - multiple condition.
• Reason - Greater reminiscence.
• No difference in inter-test forgetting
• Improvement was similar between the
  single - single and the multiple - single.
              Experiment 3
• What about free recall?
• Without explicit cueing at test, multiple
  cues may not work.
• Presented 60 word pairs - cue - target
• Three free recall tests - 7 minutes eac
• Two conditions
  – Single cue - no additional cue at study and no
    cue at test
  – Multiple cue - two additional cues at study and
    no cue at test
                 Results
• Performance improved for both conditions.
• But, the improvement was greater in the
  multiple cue than in the single cue
  condition.
• Reason - Greater reminiscence.
• No difference in inter-test forgetting.
  Our initial conclusion was….
• Multiple cues produce greater hypermnesia.
                    But…..
• Is it really the multiple retrieval cues?
• Hunt and colleagues
   – Hypermnesia is based on relative contributions
     of relational and item-specific processing.
   – Relational processing - reduced inter-test
     forgetting.
   – Item-specific processing - increase
     reminiscence.
         What are we doing?
• Asking participants to attach three cues that
  are related to one target.
• E.g., war, kill, loud - bomb.
• These cues may direct participants’
  attention to unique characteristics of the
  target word.
• This is the definition of item-specific
  processing
           Reinterpretation
• Multiple cues produce greater hypermnesia
  because multiple cues induce greater item-
  specific processing.
• How to test this?
 Our approach (Otani,Widner, &
            Throne)
• Manipulate both the number of cues and
  processing condition.
                        Item specific   Relational

Single
Multiple cue-given
Multiple cue-Generate
                Prediction
• If the number of cues is important -
  Multiple cues would produce greater
  hypermnesia regardless of processing
  condition.
• If processing condition is important - There
  would be an interaction.
         Nature of interaction
• If cues are inducing item-specific
  processing, they are redundant with the
  item-specific processing task participants
  are already performing.
• Redundant processing - no additional
  benefit.
• No effect of the number of cues.
• But, for the relational processing condition,
  the cues would induce non-redundant
  processing.
• Non-redundant processing - additive effect.
• The greatest benefit of non-redundant
  processing should occur in the Multiple-cue
  generate condition (i.e., greatest
  hypermnesia).
                       Results
                  T1      T2      T3      T3-T1   %
Intentional
    Single        19.85   20.40   20.85   1.00     5.00
    M. Given      17.00   18.75   18.80   1.80    11.00
    M. Generate   22.85   24.70   25.80   2.95    13.00
Item-specific
    Single        20.60   21.45   23.45   2.85    14.00
    M. Given      15.00   15.85   16.85   1.85    12.00
    M. Generate   20.00   20.65   21.55   1.55     8.00
Relational
    Single        12.30   13.10   13.35   1.05     8.00
    M. Given      12.75   14.05   15.30   2.55    20.00
    M. Generate   20.45   23.05   24.45   4.00    20.00
Significant three-way interaction
• Separate ANOVA on each processing
• Found
  – The number of cues interacted with test in the
    intentional and relational processing condition.
  – The number of cues DID NOT interact with test
    in the item-specific processing condition.
                   Why?
• Possible - it’s not the number of cues, but
  the processing that is important.
• What else can we look at?
   Reminiscence and Forgetting
               Int    Isp    Rp
Reminiscence
  Single       1.85   3.05   3.05
  M. Given     2.70   3.00   3.75
  M. Gen       3.60   2.90   5.65
Forgetting
  Single       1.05   0.85   2.25
  M. Given     1.05   1.55   1.55
  M. Gen       0.80   1.95   1.85
               Well …….
• Reminiscence - Should mirror the net recall.
  It does. But, the Processing x Number of
  cue is only marginally significant.
• Forgetting - The greater the relational
  processing, the lower the forgetting should
  be. The greater the item-specific
  processing, the higher the forgetting should
  be.
                  So….
• The results indicate that the type of
  processing is important.
• But, results are not completely consistent
  with Hunt and colleagues’ prediction.
• Problem - maybe due to retrieval test. Cued
  recall versus Free recall.
              Conclusion
• Currently two theories are viable as the
  explanation of hypermnesia.
• One is Roediger and colleagues explanation
  based on the notions of incrementing and
  alternative retrieval routes.
• The other is Hunt and colleagues
  explanation based on the notions of
  relational and item-specific processing.

				
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