Paper 1 - Memory
Capacity of the Short Term Memory
Jacobs 1887 - He gave a number of digits and letters to participants and they had to
recall them in order. He would extend the amount of digits and letters by one each
time. The mean digit span was 9.3 items and the mean letter span was slightly lower
at 7.3 digits
Miller 1956 - he concluded that on average we can recall 7 items (7+-2) a range of
5-9 items
Cowan 2001 - Stated that a person can remember 4 chunks of information
Evaluation of Capacity
A weakness of Jacobs’ study is that it lacked validity. His study was concluded a long
time ago and early research often lacked adequate control so participants could
have been distracted. Results might not be as valid as there were confounding
variables that were not controlled. However results of this study have been
confirmed in other research which supports its validity.
A limitation of Miller’s research is that he may have overestimated the capacity of the
STM. Cowan reviewed other research and concluded that the capacity of the STM is
4 chunks. The lower end of Miller’s estimate of 5 items may be more appropriate
than 7 items. Additionally Simon (1974) said the size of the chunks matter as people
have a shorter memory for larger chunks.
Capacity of Long Term Memory and Sensory Register
Long term memory has a potentially infinite capacity however there has been no
research to measure its infinite capacity. The capacity of the sensory register is
unlimited.
Duration of Short Term Memory
The duration of the STM is 18-30 seconds
Peterson and Peterson (1959)
Aim: To investigate how long items will stay in the STM without rehearsal
Procedure: 24 university students were presented consonant syllables and a three
digit number for example EJH 548
They were then asked to count back in 3’s or 4’s from their 3 digit number which
stopped rehearsal of the consonant syllable. AFter intervals of 3,6,9,12,15 or 18,
participants were asked to stop counting and repeat the syllable
Results: 90% recalled correctly with a 3 second interval
, 20% recalled correctly with a 9 second interval
2% recalled correctly with a 18 second interval
Conclusion: Information decays rapidly in the STM and has a very short duration
when verbal intervention is prevented
Duration of Long Term Memory
Bahrick et al (1975)
Aim: To explore the amount of time memories can be retained
Procedure: Tested 400 participants aged 17-74 on their memory of classmates. They
were asked to put names to faces from their high school yearbook. Memory tests
including recognising pictures, matching names and pictures and recalling names
with no picture which was called free recall
Results: 905 accurate when tested 15 years of graduation for identifying faces
70% accurate when tested 48 years after graduation
Free recall was 60% accurate after 15 years, dropping to 30% after 48 years
Conclusion: The more time that passes the fewer amount of memories are retained
Evaluation of Duration
A limitation of Peterson and Peterson’s study was that the material was artificial.
Trying to memorize consonant syllables does not reflect most real life memory
activities. This means that their study lacked ecological validity. However we do try to
remember meaningless things such as phone numbers, so the study is not
completely irrelevant.
Another limitation of their study is that it didn’t measure what it set out to measure.
Participants were counting the numbers in their STM which may displace the
syllables being remembered. This means that in Petersons’ study, forgetting was due
to displacement rather than decay. Additionally Reitman (1974) used auditory tones
instead of numbers so displacement wouldn’t occur and found the duration of the
STM was longer.
A strength of Bahrick’s study is that it had high external validity. Real life meaningful
memories were used for the study. But such real-life research has confounding
variables which are not controlled as participants may have looked at their yearbook
photos and rehearsed their memories over the years. When studies of the ltm have
been conducted with meaningless pictures to be remembered, recall rates were
lower.
Capacity of the Short Term Memory
Jacobs 1887 - He gave a number of digits and letters to participants and they had to
recall them in order. He would extend the amount of digits and letters by one each
time. The mean digit span was 9.3 items and the mean letter span was slightly lower
at 7.3 digits
Miller 1956 - he concluded that on average we can recall 7 items (7+-2) a range of
5-9 items
Cowan 2001 - Stated that a person can remember 4 chunks of information
Evaluation of Capacity
A weakness of Jacobs’ study is that it lacked validity. His study was concluded a long
time ago and early research often lacked adequate control so participants could
have been distracted. Results might not be as valid as there were confounding
variables that were not controlled. However results of this study have been
confirmed in other research which supports its validity.
A limitation of Miller’s research is that he may have overestimated the capacity of the
STM. Cowan reviewed other research and concluded that the capacity of the STM is
4 chunks. The lower end of Miller’s estimate of 5 items may be more appropriate
than 7 items. Additionally Simon (1974) said the size of the chunks matter as people
have a shorter memory for larger chunks.
Capacity of Long Term Memory and Sensory Register
Long term memory has a potentially infinite capacity however there has been no
research to measure its infinite capacity. The capacity of the sensory register is
unlimited.
Duration of Short Term Memory
The duration of the STM is 18-30 seconds
Peterson and Peterson (1959)
Aim: To investigate how long items will stay in the STM without rehearsal
Procedure: 24 university students were presented consonant syllables and a three
digit number for example EJH 548
They were then asked to count back in 3’s or 4’s from their 3 digit number which
stopped rehearsal of the consonant syllable. AFter intervals of 3,6,9,12,15 or 18,
participants were asked to stop counting and repeat the syllable
Results: 90% recalled correctly with a 3 second interval
, 20% recalled correctly with a 9 second interval
2% recalled correctly with a 18 second interval
Conclusion: Information decays rapidly in the STM and has a very short duration
when verbal intervention is prevented
Duration of Long Term Memory
Bahrick et al (1975)
Aim: To explore the amount of time memories can be retained
Procedure: Tested 400 participants aged 17-74 on their memory of classmates. They
were asked to put names to faces from their high school yearbook. Memory tests
including recognising pictures, matching names and pictures and recalling names
with no picture which was called free recall
Results: 905 accurate when tested 15 years of graduation for identifying faces
70% accurate when tested 48 years after graduation
Free recall was 60% accurate after 15 years, dropping to 30% after 48 years
Conclusion: The more time that passes the fewer amount of memories are retained
Evaluation of Duration
A limitation of Peterson and Peterson’s study was that the material was artificial.
Trying to memorize consonant syllables does not reflect most real life memory
activities. This means that their study lacked ecological validity. However we do try to
remember meaningless things such as phone numbers, so the study is not
completely irrelevant.
Another limitation of their study is that it didn’t measure what it set out to measure.
Participants were counting the numbers in their STM which may displace the
syllables being remembered. This means that in Petersons’ study, forgetting was due
to displacement rather than decay. Additionally Reitman (1974) used auditory tones
instead of numbers so displacement wouldn’t occur and found the duration of the
STM was longer.
A strength of Bahrick’s study is that it had high external validity. Real life meaningful
memories were used for the study. But such real-life research has confounding
variables which are not controlled as participants may have looked at their yearbook
photos and rehearsed their memories over the years. When studies of the ltm have
been conducted with meaningless pictures to be remembered, recall rates were
lower.
