Describe and evaluate research into coding, capacity and duration of memory (16 marks)
A01
Coding: Changing the format of information. The process of converting info from one form to another.
Experiment: Baddeley (1966)
Procedure: PPs were asked to learn one of four word lists:
- Acoustically similar - Acoustically dissimilar - Semantically similar - Semantically dissimilar -
PPs either recalled the list immediately (STM) or after a timed delay (LTM)
Results: The type of error made depended on both the type of list and the time delay
- When recalling from STM PPs made more acoustic errors
- When recalling from LTM PPs made more semantic errors
Suggests that STM uses an acoustic code whilst LTM uses a semantic one.
A01
Capacity: The amount of information that can be held in memory.
- Experiment 1: Jacobs (digit span technique)
Procedure: The researcher gives for example 4 digits and then the participants are asked to recall these in the
correct order out loud. If they get it right they then give them 5 digits and so on until the participant can’t
recall the order correctly. This determines the person’s digit span.
Results: Mean span for digits was 9.3 and for letters 7.3
- Experiment 2: Miller (chunking)
Generally it is found that PPs are able to recall between 5 and 9 chunks of information (i.e. 7±2 chunks) in
immediate serial recall tasks -This represents the capacity of STM.
Results: A rule can be used to chunk information together, allowing STM to hold more.
A01
Duration: The length of time information remains in memory.
- Experiment 1: Peterson & Peterson (duration of STM)
Procedure: PPs presented with ‘trigrams’ (CVC nonsense syllables) and asked to recall them (accurately & in
order). Between exposure & recall there was a delay in which they did an interference task the length of the
delay was varied. 24 undergraduate students took part. Results obtained by plotting recall against length of
delay
Results: Recall declined steadily with time:
- After 3s 80% correct
- After 6s less than 50%
- After 18s less than 10%
Information is lost rapidly from STM, which seems to have a duration of about 20s if nothing is done to
maintain the info (i.e. rehearsal).
- Experient 2: Bahrick et al (Test of LTM using naturalistic materials)
Procedure: 392 US PPs aged 17 and 74 who had left highschool 1-48 years previously tested for recall of
classmates.
- Free recall test where pps recalled all the names of their graduating class
- Recognition of photos
- Name recognition & photo matching
Results: Recall was remarkably high
- 80% accuracy for name recognition at 48yrs
- 30% accuracy for free recall at 30yrs
Supports the idea that LTM can store some types of info for a very long time. Free recall becomes more
difficult over time, but recognition does not diminish much.
A03
A limitation of the research on coding is the use of artificial stimuli.
Baddeley didn’t use meaningful materials. Instead he used word lists that had no personal meaning to the pps.
As a result we should be cautious of generalising such results due to the low ecological validity of the
experiment. For example, when processing more meaningful information, people may use semantic coding
even for STM tasks. This suggests that the findings from this study have limited application.
However…
Baddeley’s experiment is reliable. If he wanted to repeat it with the same pps under the same conditions using
,the same word lists, then he would have been able to do so. This would have allowed him to check for
consistency of his findings.
A03
One limitation of Miller’s research is that he may have overestimated the capacity of STM.
Cowan reviewed other research and concluded that the capacity of STM was only about 4 chunks.
This suggests that the lower end of Miller’s estimate (5 items) is more appropriate than 5 items.
A03
One limitation is that Peterson & Peterson used a small sample of 24 psychology students.
The psychology students may have encountered the MSM of memory previously and therefore may have
demonstrated demand characteristics by changing their behaviour to assist the experimenter. Secondly, the
memory of psychology students may be different from that of other people, especially if they had previously
studied strategies for memory improvement. As a result we are unable to generalise the results of this study to
non‐psychology students.
However…
Peterson & Peterson’s study was highly controlled and took place in a laboratory of Indiana University. As a
result Peterson & Peterson had a high degree of control for extraneous variables, which makes their
procedure easy to replicate to test reliability.
, Discuss the multi-store model of memory (16 marks)
A01
MSM -
Sensory register: all stimuli from the environment pass through.
Capacity - very high
Duration - less than ½ second
Encoding - modality-specific =Echoic: acoustic Iconic: Visual
Forgetting - Decay
Attention is a key process to transfer info from the sensory register into the STM.
A01
STM-
Capacity - 7±2 items
Duration - 18 seconds unless rehearsed
Encoding - mainly acoustic
Forgetting - decay/displacement
Maintenance rehearsal occurs when we repeat material - it stays in the STM
Prolonged rehearsal, if rehearsed and will eventually move into the LTM.
LTM-
Capacity - Too big to measure
Duration - up to a lifetime
Encoding - mainly semantic
Forgetting - decay/ inference
If we want to recall info from the LTM it has to be transferred back to the STM through retrieval.
A03
One strength of the research into the MSM of memory is Baddeley’s research into coding in STM.
He used 5 words & asked for immediate recall . He used 4 lists. Words that sounded similar were hardest to
remember when we are using the STM. The confusion of acoustically similar words demonstrated the
importance of sound in STM. We also mix up words that have similar meanings when we use our LTM. He
concluded that STM codes acoustically and LTM codes semantically. This study provides support for the
MSM as it proves that there are multiple stores in our memory, as per the MSM’s prediction.
However…
A limitation of the research on coding is the use of artificial stimuli. Baddeley didn’t use meaningful
materials. Instead he used word lists that had no personal meaning to the pps. As a result we should be
cautious of generalising such results due to the low ecological validity of the experiment.
A03
One strength of MSM is from the case study of Clive Wearing. CW contracted a virus that caused severe
amnesia (memory loss). Following the virus, Wearing could only remember information for 20‐ 30 seconds;
however, he was able to recall information from his past, for example his wife’s name. Wearing was unable to
transfer information from his STM to his LTM, but was able to retrieve information successfully. Wearing’s
case supports the idea that memories are formed by passing information from one store to the next in a linear
fashion and that damage to any part of the MSM can cause memory impairment. This is in line with the
prediction made by the model.
However…
A limitation of this research is that it’s only based on one person (CW). As a result, the population validity of
this case study is low and consequently it can’t be generalised to the target population.
A03
One limitation of the MSM is the unitary STM. This is because research shows that at the very least there
must be one ST store to process visual info and another one to process auditory information. The WMM
suggests that the STM isn’t unitary. The WMM proposed by Baddeley and Hitch (1974) showed that short
term memory is more than just one simple unitary store and comprises different components (e.g. central
executive, visuo-spatial scratch pad etc.). This suggests that the STM isn’t unitary as initially suggested
which shows that the research into the MSM is flawed.
A03
One limitation of the MSM is that follow-up research has shown that there is more than one type of LTM.
A01
Coding: Changing the format of information. The process of converting info from one form to another.
Experiment: Baddeley (1966)
Procedure: PPs were asked to learn one of four word lists:
- Acoustically similar - Acoustically dissimilar - Semantically similar - Semantically dissimilar -
PPs either recalled the list immediately (STM) or after a timed delay (LTM)
Results: The type of error made depended on both the type of list and the time delay
- When recalling from STM PPs made more acoustic errors
- When recalling from LTM PPs made more semantic errors
Suggests that STM uses an acoustic code whilst LTM uses a semantic one.
A01
Capacity: The amount of information that can be held in memory.
- Experiment 1: Jacobs (digit span technique)
Procedure: The researcher gives for example 4 digits and then the participants are asked to recall these in the
correct order out loud. If they get it right they then give them 5 digits and so on until the participant can’t
recall the order correctly. This determines the person’s digit span.
Results: Mean span for digits was 9.3 and for letters 7.3
- Experiment 2: Miller (chunking)
Generally it is found that PPs are able to recall between 5 and 9 chunks of information (i.e. 7±2 chunks) in
immediate serial recall tasks -This represents the capacity of STM.
Results: A rule can be used to chunk information together, allowing STM to hold more.
A01
Duration: The length of time information remains in memory.
- Experiment 1: Peterson & Peterson (duration of STM)
Procedure: PPs presented with ‘trigrams’ (CVC nonsense syllables) and asked to recall them (accurately & in
order). Between exposure & recall there was a delay in which they did an interference task the length of the
delay was varied. 24 undergraduate students took part. Results obtained by plotting recall against length of
delay
Results: Recall declined steadily with time:
- After 3s 80% correct
- After 6s less than 50%
- After 18s less than 10%
Information is lost rapidly from STM, which seems to have a duration of about 20s if nothing is done to
maintain the info (i.e. rehearsal).
- Experient 2: Bahrick et al (Test of LTM using naturalistic materials)
Procedure: 392 US PPs aged 17 and 74 who had left highschool 1-48 years previously tested for recall of
classmates.
- Free recall test where pps recalled all the names of their graduating class
- Recognition of photos
- Name recognition & photo matching
Results: Recall was remarkably high
- 80% accuracy for name recognition at 48yrs
- 30% accuracy for free recall at 30yrs
Supports the idea that LTM can store some types of info for a very long time. Free recall becomes more
difficult over time, but recognition does not diminish much.
A03
A limitation of the research on coding is the use of artificial stimuli.
Baddeley didn’t use meaningful materials. Instead he used word lists that had no personal meaning to the pps.
As a result we should be cautious of generalising such results due to the low ecological validity of the
experiment. For example, when processing more meaningful information, people may use semantic coding
even for STM tasks. This suggests that the findings from this study have limited application.
However…
Baddeley’s experiment is reliable. If he wanted to repeat it with the same pps under the same conditions using
,the same word lists, then he would have been able to do so. This would have allowed him to check for
consistency of his findings.
A03
One limitation of Miller’s research is that he may have overestimated the capacity of STM.
Cowan reviewed other research and concluded that the capacity of STM was only about 4 chunks.
This suggests that the lower end of Miller’s estimate (5 items) is more appropriate than 5 items.
A03
One limitation is that Peterson & Peterson used a small sample of 24 psychology students.
The psychology students may have encountered the MSM of memory previously and therefore may have
demonstrated demand characteristics by changing their behaviour to assist the experimenter. Secondly, the
memory of psychology students may be different from that of other people, especially if they had previously
studied strategies for memory improvement. As a result we are unable to generalise the results of this study to
non‐psychology students.
However…
Peterson & Peterson’s study was highly controlled and took place in a laboratory of Indiana University. As a
result Peterson & Peterson had a high degree of control for extraneous variables, which makes their
procedure easy to replicate to test reliability.
, Discuss the multi-store model of memory (16 marks)
A01
MSM -
Sensory register: all stimuli from the environment pass through.
Capacity - very high
Duration - less than ½ second
Encoding - modality-specific =Echoic: acoustic Iconic: Visual
Forgetting - Decay
Attention is a key process to transfer info from the sensory register into the STM.
A01
STM-
Capacity - 7±2 items
Duration - 18 seconds unless rehearsed
Encoding - mainly acoustic
Forgetting - decay/displacement
Maintenance rehearsal occurs when we repeat material - it stays in the STM
Prolonged rehearsal, if rehearsed and will eventually move into the LTM.
LTM-
Capacity - Too big to measure
Duration - up to a lifetime
Encoding - mainly semantic
Forgetting - decay/ inference
If we want to recall info from the LTM it has to be transferred back to the STM through retrieval.
A03
One strength of the research into the MSM of memory is Baddeley’s research into coding in STM.
He used 5 words & asked for immediate recall . He used 4 lists. Words that sounded similar were hardest to
remember when we are using the STM. The confusion of acoustically similar words demonstrated the
importance of sound in STM. We also mix up words that have similar meanings when we use our LTM. He
concluded that STM codes acoustically and LTM codes semantically. This study provides support for the
MSM as it proves that there are multiple stores in our memory, as per the MSM’s prediction.
However…
A limitation of the research on coding is the use of artificial stimuli. Baddeley didn’t use meaningful
materials. Instead he used word lists that had no personal meaning to the pps. As a result we should be
cautious of generalising such results due to the low ecological validity of the experiment.
A03
One strength of MSM is from the case study of Clive Wearing. CW contracted a virus that caused severe
amnesia (memory loss). Following the virus, Wearing could only remember information for 20‐ 30 seconds;
however, he was able to recall information from his past, for example his wife’s name. Wearing was unable to
transfer information from his STM to his LTM, but was able to retrieve information successfully. Wearing’s
case supports the idea that memories are formed by passing information from one store to the next in a linear
fashion and that damage to any part of the MSM can cause memory impairment. This is in line with the
prediction made by the model.
However…
A limitation of this research is that it’s only based on one person (CW). As a result, the population validity of
this case study is low and consequently it can’t be generalised to the target population.
A03
One limitation of the MSM is the unitary STM. This is because research shows that at the very least there
must be one ST store to process visual info and another one to process auditory information. The WMM
suggests that the STM isn’t unitary. The WMM proposed by Baddeley and Hitch (1974) showed that short
term memory is more than just one simple unitary store and comprises different components (e.g. central
executive, visuo-spatial scratch pad etc.). This suggests that the STM isn’t unitary as initially suggested
which shows that the research into the MSM is flawed.
A03
One limitation of the MSM is that follow-up research has shown that there is more than one type of LTM.
