Coding, Capacity and Duration
Memory = The process by which we retain information
Coding = The format in which information is stored
Capacity = The amount of information that can be held in a memory store
Duration = The length of time in which information can be held in a memory store
Short term memory (STM) = The limited- capacity memory store
• Coding = Acoustic
• Capacity = Between 5 and 9 items
• Duration = 18 - 30 seconds
Long term memory (LTM) = The permanent memory store
• Coding = Semantic
• Capacity = Unlimited
• Duration = Potential lifetime
Research on coding: Baddeley
Coding = The process of converting info from one form to another
METHOD =
• 4 groups of participants were each given different word lists:
• Group 1 - Acoustically similar words
• Group 2 - Acoustically dissimilar words
• Group 3 - Semantically similar words
• Group 4 - Semantically dissimilar words
• Participants were then asked to recall them in the correct order immediately after hearing them (to test STM)
and then 20 mins after hearing them (to test LTM)
FINDINGS =
• When testing STM recall, they did worse in acoustically similar words. This is because there
was acoustic confusion showing that STM relies on how words sound
• When testing LTM recall, they did worse in semantically similar words. This is because there
was semantic confusion showing that LTM relies on what words mean
Artificial stimuli -
Word lists have no personal meaning to participants. Therefore, we can’t
generalise findings to real life memory tasks.
Some may use semantic coding for STM recall and so findings have
limited application
, Coding, Capacity and Duration
Research on capacity:
Jacobs
METHOD =
• Measured digit span by giving participants digits to recall in the correct order. Each
time, the number of digits increases until the participant is unable to recall correctly
FINDINGS =
• Mean digit span was 9.3. Mean letter span was 7.3
Lacks validity - Early psychological research often lacked control.
For example, some participants may of been distracted and
therefore the study had confounding variables.
Miller
• He noticed that many things come in sevens eg days of the week. So, he concluded
that the capacity of STM is 7( plus or minus 2)
• He suggests that people use chunking = grouping information together in order to
increase memory capacity
Not so many chunks - Miller overestimated the capacity of STM.
Cowan concluded that the capacity of STM is only 4. This means that
the lower end (5) of Miller’s estimate is more appropriate than 7.
, Coding, Capacity and Duration
Research on duration:
Peterson and Peterson
Duration of STM:
METHOD =
• 24 students took part in 8 trials - in each trial, students were given a trigram to remember eg MCD
and to count backwards from a 3 digit number. This number acts as a distraction to prevent the
rehearsal of the trigram.
• Retention interval = Participants were told to stop after different amounts of time each trial
FINDINGS =
• STM has a very short duration unless we rehearse the information
Sample is unrepresentative ( students) so findings can’t be generalised
Artificial stimuli - Memorising a trigram doesn’t reflect real life memory tasks
eg remembering info for a test. So, the study lacks internal validity.
However, sometimes we do remember meaningless things eg licence plates
so the study is still relevant
Duration of LTM: Bahrick
METHOD =
• 392 participants who had a wide age range
• Their high school year books were obtained and recall was tested by:
• A photo recognition test
OR
• Free recall test where names of their class had to be recalled without photos
FINDINGS =
• Participants tested within 15 years of graduation were 90% accurate in photo
recognition. However, those tested after a longer time, were about 70% accurate
• Free recall after 15 years was about 60% accurate
• Shows that LTM can last a very long time indeed
Higher ecological validity - real life meaningful memories were studied
However , there may of been confounding variables such as some participants
regularly looking over their yearbook photos
Memory = The process by which we retain information
Coding = The format in which information is stored
Capacity = The amount of information that can be held in a memory store
Duration = The length of time in which information can be held in a memory store
Short term memory (STM) = The limited- capacity memory store
• Coding = Acoustic
• Capacity = Between 5 and 9 items
• Duration = 18 - 30 seconds
Long term memory (LTM) = The permanent memory store
• Coding = Semantic
• Capacity = Unlimited
• Duration = Potential lifetime
Research on coding: Baddeley
Coding = The process of converting info from one form to another
METHOD =
• 4 groups of participants were each given different word lists:
• Group 1 - Acoustically similar words
• Group 2 - Acoustically dissimilar words
• Group 3 - Semantically similar words
• Group 4 - Semantically dissimilar words
• Participants were then asked to recall them in the correct order immediately after hearing them (to test STM)
and then 20 mins after hearing them (to test LTM)
FINDINGS =
• When testing STM recall, they did worse in acoustically similar words. This is because there
was acoustic confusion showing that STM relies on how words sound
• When testing LTM recall, they did worse in semantically similar words. This is because there
was semantic confusion showing that LTM relies on what words mean
Artificial stimuli -
Word lists have no personal meaning to participants. Therefore, we can’t
generalise findings to real life memory tasks.
Some may use semantic coding for STM recall and so findings have
limited application
, Coding, Capacity and Duration
Research on capacity:
Jacobs
METHOD =
• Measured digit span by giving participants digits to recall in the correct order. Each
time, the number of digits increases until the participant is unable to recall correctly
FINDINGS =
• Mean digit span was 9.3. Mean letter span was 7.3
Lacks validity - Early psychological research often lacked control.
For example, some participants may of been distracted and
therefore the study had confounding variables.
Miller
• He noticed that many things come in sevens eg days of the week. So, he concluded
that the capacity of STM is 7( plus or minus 2)
• He suggests that people use chunking = grouping information together in order to
increase memory capacity
Not so many chunks - Miller overestimated the capacity of STM.
Cowan concluded that the capacity of STM is only 4. This means that
the lower end (5) of Miller’s estimate is more appropriate than 7.
, Coding, Capacity and Duration
Research on duration:
Peterson and Peterson
Duration of STM:
METHOD =
• 24 students took part in 8 trials - in each trial, students were given a trigram to remember eg MCD
and to count backwards from a 3 digit number. This number acts as a distraction to prevent the
rehearsal of the trigram.
• Retention interval = Participants were told to stop after different amounts of time each trial
FINDINGS =
• STM has a very short duration unless we rehearse the information
Sample is unrepresentative ( students) so findings can’t be generalised
Artificial stimuli - Memorising a trigram doesn’t reflect real life memory tasks
eg remembering info for a test. So, the study lacks internal validity.
However, sometimes we do remember meaningless things eg licence plates
so the study is still relevant
Duration of LTM: Bahrick
METHOD =
• 392 participants who had a wide age range
• Their high school year books were obtained and recall was tested by:
• A photo recognition test
OR
• Free recall test where names of their class had to be recalled without photos
FINDINGS =
• Participants tested within 15 years of graduation were 90% accurate in photo
recognition. However, those tested after a longer time, were about 70% accurate
• Free recall after 15 years was about 60% accurate
• Shows that LTM can last a very long time indeed
Higher ecological validity - real life meaningful memories were studied
However , there may of been confounding variables such as some participants
regularly looking over their yearbook photos
