Memory
Short- and long-term memory
STM (short-term memory) and LTM (long-term memory) are often distinguished in
terms of their:
Capacity: This concerns how much data can be held in a memory store.
STM is a limited capacity store, while LTM has a potentially infinite
capacity
o Jacobs tested the capacity of the STM using digit span. He found
that the average span for digits was 9.3 and 7.3 for letters
o Miller reviewed psychological research and concluded that the span
of immediate memory is about seven items, sometimes more,
sometimes less (7=-2). He also suggested that chunking improves
the memory
Duration: A measure of how long a memory lasts before it is no longer
available
o Peterson and Peterson studied the duration of STM using 24
students. Each participant was tested over eight trials. They were
given a consonant syllable and a three-digit number. After a
retention interval of 3,6,9,12,15 or 18 seconds, during which they
were asked to count backwards from their three-digit number, they
were asked to recall the consonant syllable. On average, 90% were
correct after 3 seconds, 20% after 9 seconds and 2% after 18
seconds. This suggests that STM has a duration of less than 18
seconds
o Bahrick et al tested the duration of LTM with 400 people aged 17-74
on their memory of classmates. He did:
Photo recognition test: consisting of 50 photos, some from
the participants high school yearbook. Those tested within 15
years of graduation were about 90% accurate in identifying
faces. After 48 years, this declined to 70%
A free recall test: participants were asked to list the names
they could remember of those in their graduating class. After
15 years, recall was about 60% accurate. This dropped to
30% after 48 years
Encoding: the way information is changed so that it can be stored in
memory. It can be stored: acoustically (sounds), visually (images) or
semantically (meaning)
o Baddeley used word lists that were:
Acoustically similar but semantically different (sound alike but
have different meaning)
Semantically similar but acoustically different (similar
meaning but different sound)
In order to test the effects of acoustic and semantic similarity on
STM and LTM. He found that participants had difficulty remembering
acoustically similar words in STM but not in LTM suggesting that
STM is largely encoded acoustically whereas semantically similar
, words posed little problem for STMs but led to muddled LTMs
suggesting the LTM is largely encoded semantically
EVALUATION
The capacity of STM may be even more limited than Miller thought. Cowan
reviewed a variety of studies on the capacity of STM and concluded that STM is
likely to be limited to about four chunks
Simon found that people had a shorter memory span for larger chunks than
smaller chunks. This shows that the size of the chunk matters as It affects how
many chunks can be remembered
Jacobs found that recall increases steadily with age, 8-year-olds could remember
an average of 6.6 digits while the mean for 19-year-olds was 8.6 digits. This
might be due to changes in brain capacity and/or the development of strategies
such as chunking. This shows that individual differences could also affect the
capacity of the STM
Tests on the duration of STM were artificial to an extent. Trying to memorise
consonant syllables does not truly reflect most everyday memory activities,
where what we remember is meaningful. However, we do sometimes try to
remember fairly meaningless things. This means that, although the task was
artificial, the study does have some relevance to everyday life
Brandimote et al. found that participants used visual coding in STM when given a
visual task and prevented from engaging in any verbal rehearsal during the
retention interval before performing a visual recall task. This shows that STM
may not be exclusively acoustic
Baddeley may not have tested the LTM. The STM was tested by asking
participants to recall a word list immediately after hearing it. LTM was tested by
waiting 20 minutes. It is questionable as to whether this is really testing LTM.
This casts doubt on the validity of Baddeley’s research
The multi-store model of memory
The MSM was first described by Atkinson and Shiffrin
Short- and long-term memory
STM (short-term memory) and LTM (long-term memory) are often distinguished in
terms of their:
Capacity: This concerns how much data can be held in a memory store.
STM is a limited capacity store, while LTM has a potentially infinite
capacity
o Jacobs tested the capacity of the STM using digit span. He found
that the average span for digits was 9.3 and 7.3 for letters
o Miller reviewed psychological research and concluded that the span
of immediate memory is about seven items, sometimes more,
sometimes less (7=-2). He also suggested that chunking improves
the memory
Duration: A measure of how long a memory lasts before it is no longer
available
o Peterson and Peterson studied the duration of STM using 24
students. Each participant was tested over eight trials. They were
given a consonant syllable and a three-digit number. After a
retention interval of 3,6,9,12,15 or 18 seconds, during which they
were asked to count backwards from their three-digit number, they
were asked to recall the consonant syllable. On average, 90% were
correct after 3 seconds, 20% after 9 seconds and 2% after 18
seconds. This suggests that STM has a duration of less than 18
seconds
o Bahrick et al tested the duration of LTM with 400 people aged 17-74
on their memory of classmates. He did:
Photo recognition test: consisting of 50 photos, some from
the participants high school yearbook. Those tested within 15
years of graduation were about 90% accurate in identifying
faces. After 48 years, this declined to 70%
A free recall test: participants were asked to list the names
they could remember of those in their graduating class. After
15 years, recall was about 60% accurate. This dropped to
30% after 48 years
Encoding: the way information is changed so that it can be stored in
memory. It can be stored: acoustically (sounds), visually (images) or
semantically (meaning)
o Baddeley used word lists that were:
Acoustically similar but semantically different (sound alike but
have different meaning)
Semantically similar but acoustically different (similar
meaning but different sound)
In order to test the effects of acoustic and semantic similarity on
STM and LTM. He found that participants had difficulty remembering
acoustically similar words in STM but not in LTM suggesting that
STM is largely encoded acoustically whereas semantically similar
, words posed little problem for STMs but led to muddled LTMs
suggesting the LTM is largely encoded semantically
EVALUATION
The capacity of STM may be even more limited than Miller thought. Cowan
reviewed a variety of studies on the capacity of STM and concluded that STM is
likely to be limited to about four chunks
Simon found that people had a shorter memory span for larger chunks than
smaller chunks. This shows that the size of the chunk matters as It affects how
many chunks can be remembered
Jacobs found that recall increases steadily with age, 8-year-olds could remember
an average of 6.6 digits while the mean for 19-year-olds was 8.6 digits. This
might be due to changes in brain capacity and/or the development of strategies
such as chunking. This shows that individual differences could also affect the
capacity of the STM
Tests on the duration of STM were artificial to an extent. Trying to memorise
consonant syllables does not truly reflect most everyday memory activities,
where what we remember is meaningful. However, we do sometimes try to
remember fairly meaningless things. This means that, although the task was
artificial, the study does have some relevance to everyday life
Brandimote et al. found that participants used visual coding in STM when given a
visual task and prevented from engaging in any verbal rehearsal during the
retention interval before performing a visual recall task. This shows that STM
may not be exclusively acoustic
Baddeley may not have tested the LTM. The STM was tested by asking
participants to recall a word list immediately after hearing it. LTM was tested by
waiting 20 minutes. It is questionable as to whether this is really testing LTM.
This casts doubt on the validity of Baddeley’s research
The multi-store model of memory
The MSM was first described by Atkinson and Shiffrin
