1. Retention and
Forgetting
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2. Factors affecting
forgetting/retention
• Time (decay theory)
• Interference -> the majority of this
research is based on explicit memory
• Strength of original learning
• Acquisition Schedules
• Acquisition Variability
• Acquisition Feedback
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3. Time Theory
• Popular forgetting functions
• Y = memory strength
• T = time
• b = forgetting
• a = some initial memory strength
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4. Time Theory Functions
Linear Function: does not fit well with most forgetting
Y = a - bT rate of forgetting is constant over time.
Exponential Function: is based on physical decay, does not fit forgetting well
Y = ae-bT forgetting slows as a function of memory strength over time
Exponential Power Function
(1-c)
Y = ae-bT Wickelgren - “c” approximates .75 for most forgetting data. Fits
Wickelgren’s data well
Logarithmic Functions
Y = a - b(logT) Ebbinghaus = rate of forgetting slows w/Time Fits data very well
Power Function
-b
Y =aT rate of forgetting declines w/Time. Fits Ebbinghaus data even better
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5. Woltz Study
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6. Woltz Study
• With short intervals (up to 90 minutes) the
logarithmic, exponential-power, and power-forgetting
funcitons fit the data almost equally as well
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7. Woltz Study
• With short intervals (up to 90 minutes) the
logarithmic, exponential-power, and power-forgetting
funcitons fit the data almost equally as well
• on delayed intervals, the exponential and exponential
power functions were both poor fits eight days later
(after learning). Both of these functions overestimated
the amount of forgetting compared to the data.
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8. Woltz Study
• With short intervals (up to 90 minutes) the
logarithmic, exponential-power, and power-forgetting
funcitons fit the data almost equally as well
• on delayed intervals, the exponential and exponential
power functions were both poor fits eight days later
(after learning). Both of these functions overestimated
the amount of forgetting compared to the data.
• The power function was within the 95% confidence
interval in latency means.
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9. Woltz Study
• With short intervals (up to 90 minutes) the
logarithmic, exponential-power, and power-forgetting
funcitons fit the data almost equally as well
• on delayed intervals, the exponential and exponential
power functions were both poor fits eight days later
(after learning). Both of these functions overestimated
the amount of forgetting compared to the data.
• The power function was within the 95% confidence
interval in latency means.
• BTW, this was implicit memory data
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10. Interference
• Is there interference in implicit memory?
• Graf & Schacter (1987): the critical manipulation involved an AB, AC
interference paradigm. Interference condition subjects required to
study a list of target words (e.g., shirt - window) that had the same
stimuli (or A words) as the interference pairs (e.g., shirt - finger).
• Under the control conditions, the target and interference lists had
no words in common. (AB, CD lists)
• Proactive: AB lists before interference list; Retroactive: AB lists
after interference list
• cued recall and completion: ( shirt - win_____)
• same ( shirt - win_____) vs. different (bottle - win___)
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11. Interference
• Is there interference in implicit memory?
• Same vs. different manipulation: if recall and completion
are based solely on memory for individual B words, type
of context should not affect performance. However, if
recall and completion are based on associative memory
for word pairs, performance should be higher in the
same condition.
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12. Interference
• Is there interference in implicit memory?
• Same vs. different manipulation: if recall and completion are based solely
on memory for individual B words, type of context should not affect
performance. However, if recall and completion are based on associative
memory for word pairs, performance should be higher in the same
condition.
• no interference in the fragment completion (implicit) but interference did
occur in the cued recall (explicit). Is it the explicit act of recall that causes
interference? does this imply different memory systems?
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13. Strength of learning
• Slamecka: most people believed better the
initial learning, the slower that memory
fades. Slamecka provided evidence this may
not be the case. Rate of forgetting does not
necessarily depend on initial learning. Level
of processing and type of encoding do have
an effect on initial learning but so do
motivation and attention.
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14. Acquisition Schedule Spacing
• Expanding the rehearsal schedule such that
as much time is allowed to go by before the
repetition of the learning event is repeated
and yet still allow for successful retrieval.
• Both implicit and explicit memory are
affected by spacing.
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15. Acquisition Variability
• more variability equals better retention but
slower initial acquisition
• general vs. specific transfer
• more elaborate memories
• Things that improve retention also
promote transfere
• frequent, specific and immediate feedback
(that’s troublesome is it not?)
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16. • retrieval induced forgetting--losing some
information based on the retrieval of other
information.
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