Short- and long-term memory
Short-term memory - memory for immediate events that holds a limited amount of information
for a short amount of time. They disappear unless they are reversed. This type of memory is
sometimes referred to as working memory.
Long-term memory - memory for past events
Capacity - refers to the amount of information that can be retained in memory.
Capacity for LTM - potentially infinite capacity
Capacity for STM - limited capacity store
-Joseph Jacobs found that the average span for digits was 9.3 items and 7.3 for letters. He
suggested that it was easier to recall digits as there are 26 letters but 26 letters.
-George Miller introduced the magic number 7+- 2 which suggests that the span of immediate
memory is about seven items- sometimes more and sometimes less. He put forward that this
capacity can be increased through ‘chunking’ - converting a string of items into a number of
larger, more memorable ‘chunks' thus increasing capacity.
A03
1) Research support - A strength of Miller’s (1956) theory is that it is supported by
psychological research. For example, Jacobs (1887) conducted an experiment using a
digit span test, to examine the capacity of STM for numbers and letters. Jacobs used a
sample of 443 female students that had to repeat back a string of numbers or letters in
the same order and the number of digits/letters was gradually increased, until the
participants could no longer recall the sequence. Jacobs found that the students had an
average span of 7.3 letters and 9.3 words, which supports Miller’s notion of 7+/‐2.
However, Cowan found from a variety of studies on STM capacity and found that the
capacity is likely to be limited to about 4 chunks which means that the lower end of
Miller's range is more appropriate.
2) Individual differences - However, a problem with the capacity of STM is that there are
individual differences. Jacobs found that digit span for 8 years old is 6.6 digits and for 19
year olds was 8.6 digits. This age increase might be due to a gradual increase in brain
capacity or/and it may be that people develop strategies to improve their digit span as
they get older, such as chunking. Therefore, these individual differences need to be
considered to be able to understand STM in different types of people.
Duration - refers to how long a memory can be held for, before it is forgotten and no longer
Short-term memory - memory for immediate events that holds a limited amount of information
for a short amount of time. They disappear unless they are reversed. This type of memory is
sometimes referred to as working memory.
Long-term memory - memory for past events
Capacity - refers to the amount of information that can be retained in memory.
Capacity for LTM - potentially infinite capacity
Capacity for STM - limited capacity store
-Joseph Jacobs found that the average span for digits was 9.3 items and 7.3 for letters. He
suggested that it was easier to recall digits as there are 26 letters but 26 letters.
-George Miller introduced the magic number 7+- 2 which suggests that the span of immediate
memory is about seven items- sometimes more and sometimes less. He put forward that this
capacity can be increased through ‘chunking’ - converting a string of items into a number of
larger, more memorable ‘chunks' thus increasing capacity.
A03
1) Research support - A strength of Miller’s (1956) theory is that it is supported by
psychological research. For example, Jacobs (1887) conducted an experiment using a
digit span test, to examine the capacity of STM for numbers and letters. Jacobs used a
sample of 443 female students that had to repeat back a string of numbers or letters in
the same order and the number of digits/letters was gradually increased, until the
participants could no longer recall the sequence. Jacobs found that the students had an
average span of 7.3 letters and 9.3 words, which supports Miller’s notion of 7+/‐2.
However, Cowan found from a variety of studies on STM capacity and found that the
capacity is likely to be limited to about 4 chunks which means that the lower end of
Miller's range is more appropriate.
2) Individual differences - However, a problem with the capacity of STM is that there are
individual differences. Jacobs found that digit span for 8 years old is 6.6 digits and for 19
year olds was 8.6 digits. This age increase might be due to a gradual increase in brain
capacity or/and it may be that people develop strategies to improve their digit span as
they get older, such as chunking. Therefore, these individual differences need to be
considered to be able to understand STM in different types of people.
Duration - refers to how long a memory can be held for, before it is forgotten and no longer
