FORGETTING
Problems with Retrieval
(Forgetting)
 Availability of memory refers to whether the material is
actually there to be retrieved
 Accessibility of memory refers to the problems involved in
retrieving available information
 “Grey area” – an area of ambiguity between these two
concepts since we can never be 100% sure that what we have
forgotten is unavailable
Tulving & Pearlstone
(1966)
 They read participants lists of varying number of words (12, 24
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and 48) consisting of categories (eg. Animals) of one, two or
four examples per list, plus the category name
Participants were instructed to try to remember only the
examples
Half the participants (Group 2) free-recalled the words and
wrote them down on blank pieces of paper
The other half (Group 1) was given the category names on the
paper
Group 1 recalled more words, especially in the 48 item list when
compared to group 2
When Group 2 was given the category names, recall improved
His illustrates very well the availability/accessibility distinction
The category name acted as a contextual cue, helping to make
accessible what was available
Group 2 participants knew
Four ways of forgetting
1) Retrieval failure
- Decay theory
- Rehearsal
3) Failure to store
- Does not reach LTM
- Encoding Failures
2) Interference
- Proactive interference
- Retroactive interference
4) Motivated Forgetting
- Supression
- Represion
It’s on the tip of my
tongue (Brown & McNeill,
1966)
 Brown and McNeill gave participants dictionary definitions on
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unfamiliar words and asked them to provide the words
themselves
Most participants either knew the word or knew that they didn't
know it
Some, however were sure they knew the word but couldn't
recall it (it was on the tip of their tongue)
About half could give the word’s first letter and the number of
syllables, and often offered words which sounded like the word
or had a similar meaning.
This suggest that the required words were in memory, but the
absence of a correct retrieval cue prevented them from being
recalled
Forgetting in short–term
memory
 Trace Decay Theory
- Focuses on explaining STM forgetting in terms of its limited
duration
 *Pure trace decay is very difficult to test.
 Displacement Theory
- Focuses on explaining STM forgetting in terms of its limited
capacity
Forgetting in Long-Term
Memory
 Interference Theory
 - One explanation of LTM forgetting is that over time more and
more material will be stored and become confused together
 - Interference is most likely to occur between similar material
 -Proactive interference is where material learnt first interferes
with material learnt later
 - Retroactive interference is where material learnt at a later
time interferes with material learnt earlier
The Role of Emotion in
Forgetting
 Repression
 - Forgetting is motivated by the desire to avoid displeasure, so
embarrassing, unpleasant or anxiety-producing experiences are
repressed – pushed down in to the unconscious
 Flashbulb Memory
 - Brown and Kulik (1977) suggested some events can be
remembered in almost photographic detail – as if they are
imprinted upon the mind.
H.M. (Milner et al. 1968)
 H.M. (Milner et al. 1968)
 - H.M. is probably the single most studied amnesic patient in the history of
neuropsychology (Rose 2003)
 - He’d been suffering epileptic fits of devastating frequency since the age
of 16
 - In 1953 (aged 27) he underwent surgery aimed at alleviating his
epilepsy
 - The anterior two-thirds of his hippocampus and amygdale plus part of
the temporal lobe (both sides of his brain) were removed
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H.M. Cont.
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His surgery was fairly successful but at that time, the role of these
brain structures in memory was unknown, and he was left with severe
anterograde amnesia that is he has near normal memory of anything
learned before the surgery, but severe memory defects for event that
occurred afterwards
- His Short Term Memory is generally normal but cannot transfer into
Long Term Memory or, if he can, is unable to retrieve it.
- He has almost no knowledge of current affairs, because he forgot all
the news as soon as he’s read about it
- He has no idea of the time unless he looks at the clock
- He cannot remember that his father has died, or that his family has
moved house, and he rereads the same magazine without realising
he’s already read it
- People he met after the operation remain, in effect, total strangers to
him and he has to “get to know them” afresh each time they meet
- He’s able to learn and remember perceptual and motor skills,
although he has to be reminded each day just what skills he has.