Coding, capacity & duration
Capacity
- How much information can be held in a memory store.
- The capacity of short-term memory (STM) is between 5 & 9 items.
- The capacity of long-term memory (LTM) is potentially unlimited.
Research into the capacity of STM
- Miller made the observation that many things come in sevens: days of
the week, musical scales, deadly sins, etc.
- Jacobs then developed a way to test digit span. He would present
participants with a list of 4 numbers. If the participant recalled the
numbers in the correct order, then they were presented with a list of 5
numbers and so on.
- Researchers agree that the average person can hold 7 +/- 2 items in STM.
Duration
- The length of time information can be held in a memory store.
- Duration of STM is 18-30 seconds.
- Duration of LTM is potentially a lifetime.
Research into the duration of STM
- Peterson & Peterson (1959) investigated the duration of STM.
- Participants were given three letters to remember.
- To prevent participants from rehearsing their letters, they had to do
another task; they were asked to count backwards from a three-digit
number until they were told to stop.
- They would then have to recall their letters.
- The longer the participants had to wait before recalling their letters, the
worse their recall was.
- This shows that the duration of STM is very limited; they concluded that
the duration of STM was approximately 18 seconds.
Research into the duration of LTM
- Bahrick et al. (1975) investigated the duration of LTM.
- Participants looked through their high school yearbook and completed two
tasks.
- Task 1: they had to state whether they recognised the faces of people in
the photos.
- Task 2: they had to freely recall the names of the people in the yearbook.
- On a whole, the participant were able to successfully recognise the images
of their classmates and freely recall their classmates’ names, even
decades after they had graduated.
- This shows that the duration of LTM is incredibly long (potentially
unlimited).
Coding
- The way that a memory is encoded describes the format that information
is stored in.
- Information is mainly encoded acoustically in STM.
- Information is mainly encoded semantically in LTM.
Research into the coding of STM & LTM
- Baddeley presented participants with one of the following four-word lists:
acoustically similar words, acoustically dissimilar words, semantically
similar words & semantically dissimilar words.
, - Testing STM:
o Participants were then given the list of words in the wrong order.
Their task was to rearrange them into the correct order,
immediately after hearing the list.
o Participants in group 1 (acoustically similar) only recalled 10% of
the list accurately, other groups recalled their lists with 60-80%
accuracy.
o This suggests that participants in group 1 confused the acoustically
similar words because STM relies on acoustic processing/coding.
- Testing LTM:
o The participants did the same task, but this time there was a 20-
minute interval in between hearing the words and having to recall
the words.
o Participants in group 3 (semantically similar) performed worse on
the recall task.
o This suggests they confused the semantically similar words because
LTM relies on semantic processing/coding.
Multi-Store Model (MSM)
Sensory register
- Receives information from the environment and codes it into separate
stores within the sensory register:
o Echoic – hearing
o Iconic – visual
o Haptic – tactic/touch
o Gustatory – taste
o Olfactory – smell
- Coding: sense specific.
- Capacity: large.
- Duration: a few milliseconds.
Short-term memory (STM)
- The STM stores information received from the sensory register.
- Information is kept in the STM through maintenance rehearsal, repeating
information to yourself to keep it in mind e.g. verification code.
- Information is sent to the long-term memory through elaborative
rehearsal, attaching personal relevance/emotion to the information e.g. A-
Level results.
- Capacity: 7 +/- 2 items.
- Duration: Approximately 18-30 seconds.
- Coding: mainly acoustic.
Long-term memory (LTM)
Capacity
- How much information can be held in a memory store.
- The capacity of short-term memory (STM) is between 5 & 9 items.
- The capacity of long-term memory (LTM) is potentially unlimited.
Research into the capacity of STM
- Miller made the observation that many things come in sevens: days of
the week, musical scales, deadly sins, etc.
- Jacobs then developed a way to test digit span. He would present
participants with a list of 4 numbers. If the participant recalled the
numbers in the correct order, then they were presented with a list of 5
numbers and so on.
- Researchers agree that the average person can hold 7 +/- 2 items in STM.
Duration
- The length of time information can be held in a memory store.
- Duration of STM is 18-30 seconds.
- Duration of LTM is potentially a lifetime.
Research into the duration of STM
- Peterson & Peterson (1959) investigated the duration of STM.
- Participants were given three letters to remember.
- To prevent participants from rehearsing their letters, they had to do
another task; they were asked to count backwards from a three-digit
number until they were told to stop.
- They would then have to recall their letters.
- The longer the participants had to wait before recalling their letters, the
worse their recall was.
- This shows that the duration of STM is very limited; they concluded that
the duration of STM was approximately 18 seconds.
Research into the duration of LTM
- Bahrick et al. (1975) investigated the duration of LTM.
- Participants looked through their high school yearbook and completed two
tasks.
- Task 1: they had to state whether they recognised the faces of people in
the photos.
- Task 2: they had to freely recall the names of the people in the yearbook.
- On a whole, the participant were able to successfully recognise the images
of their classmates and freely recall their classmates’ names, even
decades after they had graduated.
- This shows that the duration of LTM is incredibly long (potentially
unlimited).
Coding
- The way that a memory is encoded describes the format that information
is stored in.
- Information is mainly encoded acoustically in STM.
- Information is mainly encoded semantically in LTM.
Research into the coding of STM & LTM
- Baddeley presented participants with one of the following four-word lists:
acoustically similar words, acoustically dissimilar words, semantically
similar words & semantically dissimilar words.
, - Testing STM:
o Participants were then given the list of words in the wrong order.
Their task was to rearrange them into the correct order,
immediately after hearing the list.
o Participants in group 1 (acoustically similar) only recalled 10% of
the list accurately, other groups recalled their lists with 60-80%
accuracy.
o This suggests that participants in group 1 confused the acoustically
similar words because STM relies on acoustic processing/coding.
- Testing LTM:
o The participants did the same task, but this time there was a 20-
minute interval in between hearing the words and having to recall
the words.
o Participants in group 3 (semantically similar) performed worse on
the recall task.
o This suggests they confused the semantically similar words because
LTM relies on semantic processing/coding.
Multi-Store Model (MSM)
Sensory register
- Receives information from the environment and codes it into separate
stores within the sensory register:
o Echoic – hearing
o Iconic – visual
o Haptic – tactic/touch
o Gustatory – taste
o Olfactory – smell
- Coding: sense specific.
- Capacity: large.
- Duration: a few milliseconds.
Short-term memory (STM)
- The STM stores information received from the sensory register.
- Information is kept in the STM through maintenance rehearsal, repeating
information to yourself to keep it in mind e.g. verification code.
- Information is sent to the long-term memory through elaborative
rehearsal, attaching personal relevance/emotion to the information e.g. A-
Level results.
- Capacity: 7 +/- 2 items.
- Duration: Approximately 18-30 seconds.
- Coding: mainly acoustic.
Long-term memory (LTM)
