MEMORY
Key terms
Coding: the format in which memory is stored in the brain
Capacity: the amount of information that can be held in a memory store
Duration: the length of time information can be held in memory
STUDIES
Coding:
-Baddeley (1966) conducted research on coding
- He gave different lists of words to 4 groups of participants to remember:
Group 1 (acoustically similar words): cat, cab, can
Group 2 (acoustically dissimilar words): pit, few, cow
Group 3 (semantically similar words): great, large, big
Group 4 (semantically dissimilar words): good, huge, hot
Ppts. were shown the original words and asked to recall them in the right order.
When they had to do this immediately (STM recall), they did worse with acoustically
similar words, whereas if they did the recall task after 20 mins (LTM recall), they did
worse with semantically similar words. We can conclude that STM is coded
acoustically and LTM is coded semantically.
Capacity:
1 - Joseph Jacobs 1889 developed a technique to measure digit span
-researcher gives ppts 4 digits and they have to recall them in the correct order. If
they are correct, the researcher gives them 5 digits etc.
-Jacobs found the mean digit span was 9.3 items and the mean letter span was 7.3
2 – George Miller 1956 made observations and noted that things come in sevens; 7
notes on a musical scale, 7 days of the week, 7 deadly sins etc.
-he suggested that this is our STM’s capacity
-the STM can remember between 5-9 items, and he called this Miller’s magic number
of 7+/-2 items, however we can increase this through chunking information together
Duration:
STM
-Margaret & Lloyd Peterson, 1959, tested 24 undergrad students and each took part
in 8 trials. On each trial, they were given a trigram (e.g., YCG) and a 3 digit number to
remember
-they were then asked to count backwards from that 3 digit number until told to stop
-on each trial, they were told to stop after 3, 6, 9, 12, 15, or 18 seconds and their
findings show that STM may have a very short duration and the recall rate was lower
the longer time went on. After 3 seconds, ppts were able to recall 80% of the trigrams
correctly, however after 18 seconds, the ppts were only able to recall 10%, showing
the duration of STM to be approx. 20 seconds without the opportunity to rehearse.
LTM
,-Bahrick et al 1975 studied 392 ppts. from the American State of Ohio between ages
17-47 and high school yearbooks were gathered
-ppts had to recall the names of people in the yearbook and had to identify whether
a photo of a person was from their yearbook or not
Photo recognition:
-ppts tested within 15 years were approx. 90% accurate in photo recognition and
after 48 years, the recall was still about 70%
Free recall:
-after 15 years this was about 60% accurate and after 48 years, this was about 30%
accurate
-ARTIFICIAL STIMULI
Baddeley’s word lists had no personal meaning to the ppts and so we may not be
able to generalise the findings of the study to different kinds of memory tasks so
when processing more meaningful information, people may code semantically, even
for STM tasks, so the findings have limited application.
-LACKS INTERNAL VALIDITY
Jacob’s study was conducted a long time ago and lacks control. For example, some
ppts may have been distracted while being tested so they may not have performed
as well as anticipated so there were confounding variables, that were not controlled
in the study.
-LACKS MUNDANE REALISM
Peterson & Peterson’s study’s stimulus material was artificial as memorising
consonant syllables doesn’t reflect most real-life memory activities. In real life, we
remember meaningful information e.g., dates and names, so the study lacks external
validity and mundane realism as it doesn’t reflect everyday memory processes.
+HIGH EXTERNAL VALIDITY
Bahrick et al studied real-life meaningful memories. When studies on LTM have been
conducted with meaningless pictures to be remembered, recall rates have been
lower. Despite this, confounding variables were not controlled in the study e.g., ppts
may have rehearsed the yearbook photos.
MULTI-STORE MODEL OF MEMORY
-Atkinson and Shiffrin (1968)
-Theoretical cognitive model of how the memory system processes information,
illustrated diagrammatically using computer terminology to describe inputs,
processes and outputs.
, Maintenance rehearsal: repeating information over & over to keep it active in STM
Elaborative rehearsal: memorisation method, involving thinking about how new
information relates to info already stored in LTM
-info travels in a linear fashion through the stores
-each store is unitary; each store can function independently
-each store has 4 fundamentally different functions (capacity, duration, encoding and
forgetting)
SENSORY REGISTER
-info is encoded from the senses and is modality specific, depending on the sense
-high capacity (over 100 million cells in each eye)
-duration is incredibly limited (visual info is held for 0.5secs before lost)
-info that is selectively attended to will transfer to STM , info that is not attended to
will be lost due to trace decay
Sperling conducted an experiment where ppts. saw a grid of digits for 50 milliseconds
and they were asked to write down all 12 items. When shown the whole grid, 5 items
were correctly recalled about 42% of the time, whereas when they were told to look
at a specific row, 3 items were correctly recalled about 75% of the time. This suggests
that sensory memory cannot hold information for long and info decays rapidly,
supporting the MSM
SHORT TERM MEMORY
-capacity is more limited than the sensory register but we can improve it easily and
we can hold onto information much easier in this store, on average 5-9 items but we
can increase the capacity through chunking
-info is encoded acoustically
-duration is between 18-30 seconds
-information is lost through displacement (new info replaces older info)
Key terms
Coding: the format in which memory is stored in the brain
Capacity: the amount of information that can be held in a memory store
Duration: the length of time information can be held in memory
STUDIES
Coding:
-Baddeley (1966) conducted research on coding
- He gave different lists of words to 4 groups of participants to remember:
Group 1 (acoustically similar words): cat, cab, can
Group 2 (acoustically dissimilar words): pit, few, cow
Group 3 (semantically similar words): great, large, big
Group 4 (semantically dissimilar words): good, huge, hot
Ppts. were shown the original words and asked to recall them in the right order.
When they had to do this immediately (STM recall), they did worse with acoustically
similar words, whereas if they did the recall task after 20 mins (LTM recall), they did
worse with semantically similar words. We can conclude that STM is coded
acoustically and LTM is coded semantically.
Capacity:
1 - Joseph Jacobs 1889 developed a technique to measure digit span
-researcher gives ppts 4 digits and they have to recall them in the correct order. If
they are correct, the researcher gives them 5 digits etc.
-Jacobs found the mean digit span was 9.3 items and the mean letter span was 7.3
2 – George Miller 1956 made observations and noted that things come in sevens; 7
notes on a musical scale, 7 days of the week, 7 deadly sins etc.
-he suggested that this is our STM’s capacity
-the STM can remember between 5-9 items, and he called this Miller’s magic number
of 7+/-2 items, however we can increase this through chunking information together
Duration:
STM
-Margaret & Lloyd Peterson, 1959, tested 24 undergrad students and each took part
in 8 trials. On each trial, they were given a trigram (e.g., YCG) and a 3 digit number to
remember
-they were then asked to count backwards from that 3 digit number until told to stop
-on each trial, they were told to stop after 3, 6, 9, 12, 15, or 18 seconds and their
findings show that STM may have a very short duration and the recall rate was lower
the longer time went on. After 3 seconds, ppts were able to recall 80% of the trigrams
correctly, however after 18 seconds, the ppts were only able to recall 10%, showing
the duration of STM to be approx. 20 seconds without the opportunity to rehearse.
LTM
,-Bahrick et al 1975 studied 392 ppts. from the American State of Ohio between ages
17-47 and high school yearbooks were gathered
-ppts had to recall the names of people in the yearbook and had to identify whether
a photo of a person was from their yearbook or not
Photo recognition:
-ppts tested within 15 years were approx. 90% accurate in photo recognition and
after 48 years, the recall was still about 70%
Free recall:
-after 15 years this was about 60% accurate and after 48 years, this was about 30%
accurate
-ARTIFICIAL STIMULI
Baddeley’s word lists had no personal meaning to the ppts and so we may not be
able to generalise the findings of the study to different kinds of memory tasks so
when processing more meaningful information, people may code semantically, even
for STM tasks, so the findings have limited application.
-LACKS INTERNAL VALIDITY
Jacob’s study was conducted a long time ago and lacks control. For example, some
ppts may have been distracted while being tested so they may not have performed
as well as anticipated so there were confounding variables, that were not controlled
in the study.
-LACKS MUNDANE REALISM
Peterson & Peterson’s study’s stimulus material was artificial as memorising
consonant syllables doesn’t reflect most real-life memory activities. In real life, we
remember meaningful information e.g., dates and names, so the study lacks external
validity and mundane realism as it doesn’t reflect everyday memory processes.
+HIGH EXTERNAL VALIDITY
Bahrick et al studied real-life meaningful memories. When studies on LTM have been
conducted with meaningless pictures to be remembered, recall rates have been
lower. Despite this, confounding variables were not controlled in the study e.g., ppts
may have rehearsed the yearbook photos.
MULTI-STORE MODEL OF MEMORY
-Atkinson and Shiffrin (1968)
-Theoretical cognitive model of how the memory system processes information,
illustrated diagrammatically using computer terminology to describe inputs,
processes and outputs.
, Maintenance rehearsal: repeating information over & over to keep it active in STM
Elaborative rehearsal: memorisation method, involving thinking about how new
information relates to info already stored in LTM
-info travels in a linear fashion through the stores
-each store is unitary; each store can function independently
-each store has 4 fundamentally different functions (capacity, duration, encoding and
forgetting)
SENSORY REGISTER
-info is encoded from the senses and is modality specific, depending on the sense
-high capacity (over 100 million cells in each eye)
-duration is incredibly limited (visual info is held for 0.5secs before lost)
-info that is selectively attended to will transfer to STM , info that is not attended to
will be lost due to trace decay
Sperling conducted an experiment where ppts. saw a grid of digits for 50 milliseconds
and they were asked to write down all 12 items. When shown the whole grid, 5 items
were correctly recalled about 42% of the time, whereas when they were told to look
at a specific row, 3 items were correctly recalled about 75% of the time. This suggests
that sensory memory cannot hold information for long and info decays rapidly,
supporting the MSM
SHORT TERM MEMORY
-capacity is more limited than the sensory register but we can improve it easily and
we can hold onto information much easier in this store, on average 5-9 items but we
can increase the capacity through chunking
-info is encoded acoustically
-duration is between 18-30 seconds
-information is lost through displacement (new info replaces older info)
