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The Nature of Memory: STM,
LTM and Duration (Page 20)
- Duration
- LTM
- Duration
- LTM refers to memories that
last anywhere from 2 hours to
100 years+
- i.e. anything that isn't
short-term
- i.e. anything that isn't
short-term
- Example: Shepard 1967 - tested
LTM duration
- Participants were shown 612
memorable pics, 1 at a time
- 1 hour later - shown some
of the pics among a set of
new 1s
- Showed perfect
regonition
- 4 months later - still able to
recognise 50% of the pics
- Showed perfect
regonition
- 1 hour later - shown some
of the pics among a set of
new 1s
- Participants were shown 612
memorable pics, 1 at a time
- More 'real life' example:
Bahrick et al 1975
- More 'real life' as the material to be
remembered was more meaningful to the
participants
- Participants (of various ages) were
asked to put names to faces from their
high school year book
- 48 years on about 70% of
people were accurate
- 48 years on about 70% of
people were accurate
- More 'real life' as the material to be
remembered was more meaningful to the
participants
- LTM refers to memories that
last anywhere from 2 hours to
100 years+
- Duration
- STM
- Key Study - Peterson &
Peterson 1959 (Landmark
study)
- What did they do?
- Enlisted 24
students from
their uni
- The experimenter said a 3 constant
syllable (with no meaning) to the
participant followed by a 3 digit number
- After hearing the syllable the participant had
to count back from the number in 3s or 4s
until told to stop + then asked to recall syllable
- Each participant was given 2
practice trials + 8 real trials
- On each trial the retention interval (time
spent counting backwards) was different:
3,6,9,12,15,18 secs
- On each trial the retention interval (time
spent counting backwards) was different:
3,6,9,12,15,18 secs
- Each participant was given 2
practice trials + 8 real trials
- The reason for the counting was
to prevent rehearsal
- After hearing the syllable the participant had
to count back from the number in 3s or 4s
until told to stop + then asked to recall syllable
- Enlisted 24
students from
their uni
- What did they find?
- Participants remembered around 90%
with 3 sec interval
- About 2% with 18 sec interval
- Results suggest - when rehearsal is
prevented STM lasts about 20 secs at
most
- Participants remembered around 90%
with 3 sec interval
- What did they do?
- Duration
- ST memories don't last long
- The info doesn't last very long +
STM can't hold much info at a time
- Rehearsal is needed to keep
the info in the STM
(re-presenting the info to the
STM)
- The result of the verbal rehearsal - the
ST memories are held in the STM
store + eventually become LT
- The result of the verbal rehearsal - the
ST memories are held in the STM
store + eventually become LT
- Rehearsal is needed to keep
the info in the STM
(re-presenting the info to the
STM)
- ST memories don't last long
- Key Study - Peterson &
Peterson 1959 (Landmark
study)
- How long a memory lasts
- LTM
- Evaluation
- The duration of STM may be even shorter
- Peterson & Peterson findings
have been challenged
- We may argue - the participants may
have been relying on more than STM
as they knew they knew they were
going to be asked to recall the items
after a distracting interval
- Marsh et al 1997
- Suggests - when participants do not
expect to be tested after this interval,
forgetting may occur after just 2 secs
- This suggests - our understanding of
STM duration may not be as clear-cut
as first thought
- This suggests - our understanding of
STM duration may not be as clear-cut
as first thought
- Suggests - when participants do not
expect to be tested after this interval,
forgetting may occur after just 2 secs
- We may argue - the participants may
have been relying on more than STM
as they knew they knew they were
going to be asked to recall the items
after a distracting interval
- Peterson & Peterson findings
have been challenged
- Not quite so short-term memory
- More recent research suggests that STM
duration is not as short as Peterson &
Peterson's study would suggest
- Nairne et al 1999
- Found - items could be recalled
after as long as 96 secs
- In this study - participants were asked to
recall the same items across trials - earlier
studies items differed
- In this study - participants were asked to
recall the same items across trials - earlier
studies items differed
- Suggests - info remains in STM for quite awhile unless it
is replaced or overwritten
- Found - items could be recalled
after as long as 96 secs
- Nairne et al 1999
- More recent research suggests that STM
duration is not as short as Peterson &
Peterson's study would suggest
- Peterson & Peterson validity
- 1 criticism of the study - only studying 1 type of memory - memory
for syllables + digits, whereas much of the time our memories are
concerned with other things, e.g what we did last night
- A 2nd criticism - Peterson & Peterson weren't actually testing
duration. When the participants were counting backwards, the
syllables could well have been displaced in STM by the digits -
wiping out the memory for the syllables
- 1 criticism of the study - only studying 1 type of memory - memory
for syllables + digits, whereas much of the time our memories are
concerned with other things, e.g what we did last night
- The duration of STM may be even shorter
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