EVALUATION:
Short Term Memory (STM) = our memory for the immediate past, e.g. remembering a phone number
Strengths:
Long Term Memory (LTM) = our memory for the past, e.g. what happened last week, last year, childhood Size of The Chunk Matters
The Sensory Register = information gathered from the sense – this store is very brief • it seems the size of the chunk affects how many chunks you can remember
STM and LTM are often distinguished in terms of their capacity, duration, and coding • Simon (1974) = found that people had a shorter memory span for larger chunks, such as eight word
------------------- phrases, than smaller chunks, such as one syllable words
• this continues to support the view that STM has a limited capacity and refines our understanding
Capacity = a measure of how much can be held in memory
→ is represented in terms of bits of information, such as a number of digits
Limitations:
→ concerns how much data can be held in a memory store
Capacity of STM May Be Even More Limited
→ STM is a limited capacity store whereas LTM has a potentially infinite capacity
• one criticism of the research investing STM is that Miller’s original findings have not been replicated
• Cowan (2001) = reviewed a variety of studies on the capacity of STM and concluded that STM is -----
• Capacity Of Sensory Register: ----------------------likely to be limited to about four chunks
→ difficult to measure as it is so brief • Vogel et al (2001) = conducted research on the capacity of STM for visual information (rather than -
→ at any one time it probably takes in everything from the senses ---------------------------verbal stimuli), found that four items were about the limit
• Capacity Of Long Term Memory: • this means that the lower end of Miller’s range is more appropriate (e.g. 7-2 which is 5)
→ difficult to measure as we hold so many memories, and there always seems to be room for more • this suggests that STM may not be as extensive as was thought
→ Standing et al (1970) = presented 2560 photos, participants recognised about 90% few days later
→ LTM is thought to have highly efficient storage system, meaning there is always room for new
memories Individual Differences
• Capacity Of Short Term Memory: can be assessed using digit span (Joseph Jacobs, 1887) • the capacity of STM is not the same for everyone
• Jacobs (1887) = also found that recall (digit span) increased steadily with age
→ 8 year olds could remember average of 6.6. digits whereas mean for 19 year olds was 8.6 digits
KEY STUDY: JACOBS (1887) → age increase may be due to changes in brain capacity, or development of strategies like chunking
• this suggests that the capacity of STM is not fixed, and individual differences may play a role
AIM: to investigate how many letters and digits can be held in the short term memory
HOW: digit span technique used; metronome paced reading
FINDINGS: 9.3 digits remembered; 7.3 letters remembered
CONCLUSIONS: the STM can hold around 7 items of information, numbers are easier to remember
Chunking = way to group information to make it meaningful
• Miller (1956) = people can remember 5 words as well as 5 letters
• Simon (1974) = found people had a shorter memory capacity for chunks that are multi-word phrases,
--------------------- vs chunks that are one-syllable words
, EVALUATION:
Duration = a measure of how long a memory lasts before it is no longer available
→ LTM potentially lasts forever, but STM doesn’t last very long – it has a short duration unless you
Strengths:
repeat the items over and over again
Testing STM was Artificial
• trying to memorise consonant syllables doesn’t truly reflect most everyday memory activities where
• Duration In The Sensory Register: different sub-stores in the sensory memory (one for each sense), -
what we are trying to remember is meaningful
----------------------------------------------each lasts for a brief period of time (a fraction of a second)
• however, we do sometimes try to remember fairly meaningless things, such as groups of numbers
→ iconic store = remembers things we have seen for a very brief time after they disappear
(phone numbers) or letters (postcodes)
→ echoic store = remembers things we have heard for a very brief period of time after sound ends
• this means although the task was artificial, the study does have some relevance to everyday life
• Duration In STM: Peterson and Peterson (1959)
• Duration In LTM: Bahrick et al (1975)
Limitations:
STM Results May Be Due To Displacement
KEY STUDY (STM): PETERSON AND PETERSON (1959)
• a criticism of Peterson’s study is that it didn’t actually measure what it set out to measure
AIM: to investigate the ‘pure’ duration of STM (when rehearsal is prevented) • in Peterson’s study participant were counting the numbers in their STM and this may displace or
HOW: participants given trigrams to recall after either 3, 6, 9, 12, 15, or 18 seconds, whilst waiting (the --- ‘overwrite’ the syllables to be remembered
---------retention interval) they counted back in 3’s from a 3 digit number • Reitman (1974): used auditory tones instead of numbers so that displacement wouldn’t occur -------
FINDINGS: 3 seconds = 90% recall, 9 seconds = 20% recall, 18 seconds = 2% ---------------------- (sounds don’t interfere with verbal rehearsal), found duration of STM was longer
CONCLUSIONS: the duration of STM is not much longer than 18 seconds • this suggests that forgetting in the Peterson’s study was due to displacement rather than decay
EVALUATION:
→ high control → low population validity
→ reliable → the numbers might have displaced
→ low ecological validity the original memory of the trigram
KEY STUDY (LTM): BAHRICK ET AL (1975)
AIM: to investigate the duration of LTM
HOW: 392 US ex high school students were given 4 tests:
1. free recall
2. photo recognition
3. name recognition
4. name and photo matching
FINDINGS: recognition easier than recall
→ tests showed good accuracy, 70% accuracy in face recognition after 4.8 years
CONCLUSIONS: classmates are rarely forgotten, a hint may be needed but memories are stored somewhere
EVALUATION:
→ ungeneralisable – may not apply to other memories
→ poor control – were the classmates still in contact?
→ high ecological validity – a realistic memory task
Short Term Memory (STM) = our memory for the immediate past, e.g. remembering a phone number
Strengths:
Long Term Memory (LTM) = our memory for the past, e.g. what happened last week, last year, childhood Size of The Chunk Matters
The Sensory Register = information gathered from the sense – this store is very brief • it seems the size of the chunk affects how many chunks you can remember
STM and LTM are often distinguished in terms of their capacity, duration, and coding • Simon (1974) = found that people had a shorter memory span for larger chunks, such as eight word
------------------- phrases, than smaller chunks, such as one syllable words
• this continues to support the view that STM has a limited capacity and refines our understanding
Capacity = a measure of how much can be held in memory
→ is represented in terms of bits of information, such as a number of digits
Limitations:
→ concerns how much data can be held in a memory store
Capacity of STM May Be Even More Limited
→ STM is a limited capacity store whereas LTM has a potentially infinite capacity
• one criticism of the research investing STM is that Miller’s original findings have not been replicated
• Cowan (2001) = reviewed a variety of studies on the capacity of STM and concluded that STM is -----
• Capacity Of Sensory Register: ----------------------likely to be limited to about four chunks
→ difficult to measure as it is so brief • Vogel et al (2001) = conducted research on the capacity of STM for visual information (rather than -
→ at any one time it probably takes in everything from the senses ---------------------------verbal stimuli), found that four items were about the limit
• Capacity Of Long Term Memory: • this means that the lower end of Miller’s range is more appropriate (e.g. 7-2 which is 5)
→ difficult to measure as we hold so many memories, and there always seems to be room for more • this suggests that STM may not be as extensive as was thought
→ Standing et al (1970) = presented 2560 photos, participants recognised about 90% few days later
→ LTM is thought to have highly efficient storage system, meaning there is always room for new
memories Individual Differences
• Capacity Of Short Term Memory: can be assessed using digit span (Joseph Jacobs, 1887) • the capacity of STM is not the same for everyone
• Jacobs (1887) = also found that recall (digit span) increased steadily with age
→ 8 year olds could remember average of 6.6. digits whereas mean for 19 year olds was 8.6 digits
KEY STUDY: JACOBS (1887) → age increase may be due to changes in brain capacity, or development of strategies like chunking
• this suggests that the capacity of STM is not fixed, and individual differences may play a role
AIM: to investigate how many letters and digits can be held in the short term memory
HOW: digit span technique used; metronome paced reading
FINDINGS: 9.3 digits remembered; 7.3 letters remembered
CONCLUSIONS: the STM can hold around 7 items of information, numbers are easier to remember
Chunking = way to group information to make it meaningful
• Miller (1956) = people can remember 5 words as well as 5 letters
• Simon (1974) = found people had a shorter memory capacity for chunks that are multi-word phrases,
--------------------- vs chunks that are one-syllable words
, EVALUATION:
Duration = a measure of how long a memory lasts before it is no longer available
→ LTM potentially lasts forever, but STM doesn’t last very long – it has a short duration unless you
Strengths:
repeat the items over and over again
Testing STM was Artificial
• trying to memorise consonant syllables doesn’t truly reflect most everyday memory activities where
• Duration In The Sensory Register: different sub-stores in the sensory memory (one for each sense), -
what we are trying to remember is meaningful
----------------------------------------------each lasts for a brief period of time (a fraction of a second)
• however, we do sometimes try to remember fairly meaningless things, such as groups of numbers
→ iconic store = remembers things we have seen for a very brief time after they disappear
(phone numbers) or letters (postcodes)
→ echoic store = remembers things we have heard for a very brief period of time after sound ends
• this means although the task was artificial, the study does have some relevance to everyday life
• Duration In STM: Peterson and Peterson (1959)
• Duration In LTM: Bahrick et al (1975)
Limitations:
STM Results May Be Due To Displacement
KEY STUDY (STM): PETERSON AND PETERSON (1959)
• a criticism of Peterson’s study is that it didn’t actually measure what it set out to measure
AIM: to investigate the ‘pure’ duration of STM (when rehearsal is prevented) • in Peterson’s study participant were counting the numbers in their STM and this may displace or
HOW: participants given trigrams to recall after either 3, 6, 9, 12, 15, or 18 seconds, whilst waiting (the --- ‘overwrite’ the syllables to be remembered
---------retention interval) they counted back in 3’s from a 3 digit number • Reitman (1974): used auditory tones instead of numbers so that displacement wouldn’t occur -------
FINDINGS: 3 seconds = 90% recall, 9 seconds = 20% recall, 18 seconds = 2% ---------------------- (sounds don’t interfere with verbal rehearsal), found duration of STM was longer
CONCLUSIONS: the duration of STM is not much longer than 18 seconds • this suggests that forgetting in the Peterson’s study was due to displacement rather than decay
EVALUATION:
→ high control → low population validity
→ reliable → the numbers might have displaced
→ low ecological validity the original memory of the trigram
KEY STUDY (LTM): BAHRICK ET AL (1975)
AIM: to investigate the duration of LTM
HOW: 392 US ex high school students were given 4 tests:
1. free recall
2. photo recognition
3. name recognition
4. name and photo matching
FINDINGS: recognition easier than recall
→ tests showed good accuracy, 70% accuracy in face recognition after 4.8 years
CONCLUSIONS: classmates are rarely forgotten, a hint may be needed but memories are stored somewhere
EVALUATION:
→ ungeneralisable – may not apply to other memories
→ poor control – were the classmates still in contact?
→ high ecological validity – a realistic memory task
