Paper 1 - Memory
Features of Short & Long Term Memory
SHORT TERM MEMORY
CAPACITY = LIMITED (7 +/- 2)
● Jacobs (1887) used this digit span to assess STM capacity and found that the average span for
digits was 9.3 items / numbers, and 7.3 for letters. He suggested that more items because there
are only 9 digits rather than 26 letters
● Miller (1956) found that the magic number for capacity was 7 items +/- 2
DURATION = LIMITED (>18 seconds)
● Peterson & Peterson (1959) studied the duration of STM using 24 students. Participants on
average were 90% correct over 3 seconds, 20% correct after 9 seconds, and only 2% correct
after 18 seconds. This suggests that STM has a very short duration, less than 18 seconds, as
long as verbal rehearsal is prevented.
CODING = ACOUSTIC
● Baddeley (1966) used word lists and found that participants had difficulty remembering words
that were acoustically different whereas semantically similar words posed little problem.
LONG TERM MEMORY
CAPACITY = POTENTIALLY UNLIMITED
DURATION = POTENTIALLY INFINITE
● Bahrick (1975) tested 400 people of various ages (17-74) on their memory of classmates. Those
who were tested within 15 years of graduation were about 90% accurate in identifying faces.
After 48 years this declined to about 70%.
CODING = SEMANTIC
● Baddeley (1966) used word lists and found that participants had difficulty remembering words
that were semantically different whereas acoustically similar words posed little problem.
Evaluations of Features of STM & LTM
Issues With Miller + Individual Differences In STM Capacity
Research investigating Miller’s original findings have never been replicated
● Cowan (2001) reviewed a variety of studies and found that STM is likely to be limited to about 4
chunks with visual information, so it is not as extensive as once thought.
+ Individual differences: Jacobs also found that digit span recall increased with age - 8 year olds
could remember an average of 6.6 digits whereas the mean for 19 year olds was 8.6 digits.
Therefore this suggests the capacity of STM is not fixed & individual differences may play a role.
, Artificial Testing Of STM Duration BUT Not LTM
Peterson & Peterson’s testing of duration involved memorising consonant syllables but this does not
truly reflect everyday memory activities, although things like postcodes or phone numbers may be an
exception
● Therefore, this study lacks ecological validity
However, Bahrick used real-life memories from high school yearbook photos, so has high ecological
validity.
● BUT, lacks population validity as he only used American university graduates (392).
Contradictory Evidence To LTM Coding + Issues With Baddeley’s Methodology
LTM may not be exclusively semantic - it can vary.
● Frost (1972) found that term recall was also related to visual areas, and Nelson & Robertson
(1972) found evidence of acoustic coding in LTM.
When testing STM, Baddeley’s participants had to recall the word lists immediately after, but when
testing LTM they only waited 20 minutes.
● So, it is questionable whether he was really testing LTM.
Features of Short & Long Term Memory
SHORT TERM MEMORY
CAPACITY = LIMITED (7 +/- 2)
● Jacobs (1887) used this digit span to assess STM capacity and found that the average span for
digits was 9.3 items / numbers, and 7.3 for letters. He suggested that more items because there
are only 9 digits rather than 26 letters
● Miller (1956) found that the magic number for capacity was 7 items +/- 2
DURATION = LIMITED (>18 seconds)
● Peterson & Peterson (1959) studied the duration of STM using 24 students. Participants on
average were 90% correct over 3 seconds, 20% correct after 9 seconds, and only 2% correct
after 18 seconds. This suggests that STM has a very short duration, less than 18 seconds, as
long as verbal rehearsal is prevented.
CODING = ACOUSTIC
● Baddeley (1966) used word lists and found that participants had difficulty remembering words
that were acoustically different whereas semantically similar words posed little problem.
LONG TERM MEMORY
CAPACITY = POTENTIALLY UNLIMITED
DURATION = POTENTIALLY INFINITE
● Bahrick (1975) tested 400 people of various ages (17-74) on their memory of classmates. Those
who were tested within 15 years of graduation were about 90% accurate in identifying faces.
After 48 years this declined to about 70%.
CODING = SEMANTIC
● Baddeley (1966) used word lists and found that participants had difficulty remembering words
that were semantically different whereas acoustically similar words posed little problem.
Evaluations of Features of STM & LTM
Issues With Miller + Individual Differences In STM Capacity
Research investigating Miller’s original findings have never been replicated
● Cowan (2001) reviewed a variety of studies and found that STM is likely to be limited to about 4
chunks with visual information, so it is not as extensive as once thought.
+ Individual differences: Jacobs also found that digit span recall increased with age - 8 year olds
could remember an average of 6.6 digits whereas the mean for 19 year olds was 8.6 digits.
Therefore this suggests the capacity of STM is not fixed & individual differences may play a role.
, Artificial Testing Of STM Duration BUT Not LTM
Peterson & Peterson’s testing of duration involved memorising consonant syllables but this does not
truly reflect everyday memory activities, although things like postcodes or phone numbers may be an
exception
● Therefore, this study lacks ecological validity
However, Bahrick used real-life memories from high school yearbook photos, so has high ecological
validity.
● BUT, lacks population validity as he only used American university graduates (392).
Contradictory Evidence To LTM Coding + Issues With Baddeley’s Methodology
LTM may not be exclusively semantic - it can vary.
● Frost (1972) found that term recall was also related to visual areas, and Nelson & Robertson
(1972) found evidence of acoustic coding in LTM.
When testing STM, Baddeley’s participants had to recall the word lists immediately after, but when
testing LTM they only waited 20 minutes.
● So, it is questionable whether he was really testing LTM.
