Retention of memories

1
Retention of memories

• The retention function
• Spacing effects
• Interference and repression

2
Forgetting

• Forgetting is the obverse of retention
• Decay hypothesis
• Interference hypothesis
• Retrieval-cue hypothesis

3
The retention function

• Ebbinghaus and Peterson Peterson
• The power law of forgetting
• More negatively accelerated than exponential
  functions
• Forgetting is very slow
• Savings, p(recall), and retrieval time all fit
  the power law
• Decay hypothesis seems to be supported

4
Practice effects on forgetting

• Practice does not affect the rate of forgetting
• Practice does affect the amount recalled after a
  particular length of delay

5
Why a power function?

• The strength equation (power law of remembering)
  approximately fits the frequency and recency with
  which information occurs in the environment
• Fits New York Times headlines, e-mail messages,
  and parents comments to children

6
Spacing effects

• Continuous paired-associates (Glenburg, 1976)
  Study interval and test interval
• bank-tail
• fish-home
• fish-???
• bank-tail
• pail-nose
• frog-girl
• pail-???
• snow-ball
• bank-???

7
Study interval should match retention interval

• In short study intervals, the second presentation
  is forgotten
• Hintzman, Block, and Summers (1973) presented
  information twice, but in two sensory modalities,
  to see which was forgotten.
• Spacing effects in the environment Massed items
  are forgotten (flash in the pan effect)
• Compare with CRF extinction effect

8
Interference

• Negative transfer Learning
• Proactive interference Forgetting
• Retroactive interference Forgetting
• Multiple associations to the same cues maximizes
  interference
• Sharing associative value Rescorla-Wagner

9
More interference

• Recognition memory tasks
• Anderson (1974)
• Occupations x locations
• Recognize probes among detractors
• Speed of recognition is inversely related to the
  number of sentences per probe.
• Activation equation
• Record activation Record strength
  Sum(Association strengths)

10
Repression

• Context effects on memory
• State-dependent recall
• Mood-dependent recall
• Emotional bocking Encoding, rehearsal, or
  repression?

11
Arousal and retention Reminiscence

• Low-arousal learned items recalled better at
  short intervals
• High-arousal learned items recalled better after
  delay
• Usually not increased memory for high-arousal
  learned items, but less forgetting
• Stimulant drugs improve memory
• High arousal times of day improve memroy

12
Eyewitness memories

• Inaccuracy is disturbing
• Flashbulb memories are intense
• Key variable Focusing of attention