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Memory
Topics:
● Coding, capacity, duration
● The multi-store model of memory
● Types of long-term memory
● The working model of memory
● Explanations for forgetting
● Factors affecting the accuracy of eyewitness testimony
● Improving the accuracy of eyewitness testimony
Coding, Capacity & Duration
Codin g Capacity Dur ation
Sen sor y r egister Modality specific Depends on modality 250 ms
Sh or t ter m m em or y Acoustic 7 ± 2 items 18-30 sec
3 sec unrehearsed
Lon g ter m m em or y Semantic Unlimited Forever
Codin g → The different information types/formats the brain uses to store memory
Capacity → How much information can be held by a store
Dur ation → How long information can be held in that store before loss
Sensor y r egister → Store is not under cognitive control like the STm or LTM,
sensory information coming from the senses is detected and recorded automatically. All
information found in the short term or long term memory stores were initially gathered
by sensory register. Information is passed on to the STM by paying attention.
Sh or t-ter m m em or y → Receives information from the sensory register by paying
attention. It passes information to the LTM through rehearsal. This is either maintenance
rehearsal (repeating the information) or elaborative rehearsal (linking to information
already in LTM). Information is passed back from the LTM with retrieval, and
information can be lost via displacement or decay.
Lon g-ter m m em or y → Information stores may last permanently and LTM may be
unlimited in the amount of information it can contain. Information comes into LTM
from STM via rehearsal and in order to use information in LTM it needs to be passed
back to short-term memory via retrieval.
,Coding LTM & STM - Baddeley
Aim : To investigate how information is coded in both short term and long term
memory
Pr ocedur e: Laboratory experiment. 4 conditions of the independent variable.
Participants were shown words and asked to recall them in the correct order.
1) Acoustically similar
2) Acoustically dissimilar
3) Semantically similar
4) Semantically dissimilar.
Fin din gs: When recalled immediately (STM) pp performed worse with acoustically
similar words. When recalled after a 20 minute (LTM) time interval they performed
worse in semantically similar words.
Con clusion : These findings suggest that information is coded acoustically in short
term memory and semantically in long term memory.
Evaluation
+ One strength of Baddeley’s study is that since the experimental method was a
lab experiment it means that there are high levels of control over extraneous
and confounding variables For example, there is high control in the
environment as the lab environment ensures that there is no background
noise or other distractions that would affect the accuracy of recall. The
consequence of this is that the researcher can ensure that any effect on the
amount of words recalled is likely to be the result of the manipulation of the
words on the list being similar/dissimilar. This is a strength as it allows for a
clear causal relationship to be established, increasing the internal validity as it
accurately measures how LTM and STM are coded. Additionally, all factors
would’ve been standardised in this lab experiment and thus increase the
reliability of the results.
Capacity STM - Jacobs
Aim : To investigate the capacity of short term memory.
Pr ocedur e: Participants were given a sequence of digits e.g. 4, 1, 8, 6 and asked to
recall in the correct order out loud. If correct they move onto the next sequence
whereby another digit is added e.g. 3, 5, 2, 1, 9. This is repeated until they cannot
recall the order correctly.
Fin din gs: Mean span for digits 9.3, mean span for letters 7.3.
Con clusion : These findings suggest that the average capacity in short term memory
is between 5-9 (7+/-2) items.
, Miller ’s findings suggested that the capacity of STM is about 7 items, plus or minus
2. He also noted that people can recall five words as easily as they can recall five
letters. We do this by CH UNK ING.
Evaluation
+ One strength of Jacob’s study is that it has been replicated. The study is a very
old one and early research in psychology often lacked adequate controls. For
example, there was less technology that could’ve helped to standardise the
procedure and eliminate confounding variables (like reading the same digits
at the same speed). Despite this, Jacobs findings have been confirmed by
other, better controlled studies, meaning the conclusion that the capacity of
short term memory is between 5-9 items is consistent and therefore reliable.
This is also a strength because it suggests that Jacobs’ study is a valid test of
digit span and an accurate measure for the capacity of short term memory.
Duration STM - Peterson & Peterson
Aim : To investigate the duration of short term memory.
Sam ple: 24 Psychology student participants completed x8 trials.
Pr ocedur e: Each trial participants were given a nonsense consonant trigram (e.g.
YRT) to remember and a 3 digit number to count backwards from to prevent
rehearsal. The distractor task was necessary as a form of control to stop participants
rehearsing the numbers which would have confounded the results. On each trial they
were told to stop after a different amount of time-E.g. 3, 6, 9, 12, 15 and 18 seconds.
Fin din gs: 80% correct after 3 seconds, 3%- correct after 18 seconds. Concluded that
the duration of the STM was approximately 18 seconds without any verbal rehearsal.
Con clusion : These findings suggest that the duration of short term memory is
limited somewhere between 18-30 seconds.
Evaluation
- One limitation of Peterson and Peterson’s study is that both the setting and
the stimulus material were artificial. Since the study was a laboratory
experiment the environment in which the study took place was very
controlled. Additionally the task itself was regarded as unrealistic. The
procedure gave the participants nonsense trigrams which would not be
reflective of how our memory works on a daily basis as we use our memory (in
reality, we use it for shopping lists rather than random consonants and digits).
The consequence of this is that the findings relating to the duration of short
term memory are not representative of real life settings or tasks. This is a
limitation as it means any conclusions drawn about the duration of the short
term memory cannot be generalised to real life situations or tasks such as
Memory
Topics:
● Coding, capacity, duration
● The multi-store model of memory
● Types of long-term memory
● The working model of memory
● Explanations for forgetting
● Factors affecting the accuracy of eyewitness testimony
● Improving the accuracy of eyewitness testimony
Coding, Capacity & Duration
Codin g Capacity Dur ation
Sen sor y r egister Modality specific Depends on modality 250 ms
Sh or t ter m m em or y Acoustic 7 ± 2 items 18-30 sec
3 sec unrehearsed
Lon g ter m m em or y Semantic Unlimited Forever
Codin g → The different information types/formats the brain uses to store memory
Capacity → How much information can be held by a store
Dur ation → How long information can be held in that store before loss
Sensor y r egister → Store is not under cognitive control like the STm or LTM,
sensory information coming from the senses is detected and recorded automatically. All
information found in the short term or long term memory stores were initially gathered
by sensory register. Information is passed on to the STM by paying attention.
Sh or t-ter m m em or y → Receives information from the sensory register by paying
attention. It passes information to the LTM through rehearsal. This is either maintenance
rehearsal (repeating the information) or elaborative rehearsal (linking to information
already in LTM). Information is passed back from the LTM with retrieval, and
information can be lost via displacement or decay.
Lon g-ter m m em or y → Information stores may last permanently and LTM may be
unlimited in the amount of information it can contain. Information comes into LTM
from STM via rehearsal and in order to use information in LTM it needs to be passed
back to short-term memory via retrieval.
,Coding LTM & STM - Baddeley
Aim : To investigate how information is coded in both short term and long term
memory
Pr ocedur e: Laboratory experiment. 4 conditions of the independent variable.
Participants were shown words and asked to recall them in the correct order.
1) Acoustically similar
2) Acoustically dissimilar
3) Semantically similar
4) Semantically dissimilar.
Fin din gs: When recalled immediately (STM) pp performed worse with acoustically
similar words. When recalled after a 20 minute (LTM) time interval they performed
worse in semantically similar words.
Con clusion : These findings suggest that information is coded acoustically in short
term memory and semantically in long term memory.
Evaluation
+ One strength of Baddeley’s study is that since the experimental method was a
lab experiment it means that there are high levels of control over extraneous
and confounding variables For example, there is high control in the
environment as the lab environment ensures that there is no background
noise or other distractions that would affect the accuracy of recall. The
consequence of this is that the researcher can ensure that any effect on the
amount of words recalled is likely to be the result of the manipulation of the
words on the list being similar/dissimilar. This is a strength as it allows for a
clear causal relationship to be established, increasing the internal validity as it
accurately measures how LTM and STM are coded. Additionally, all factors
would’ve been standardised in this lab experiment and thus increase the
reliability of the results.
Capacity STM - Jacobs
Aim : To investigate the capacity of short term memory.
Pr ocedur e: Participants were given a sequence of digits e.g. 4, 1, 8, 6 and asked to
recall in the correct order out loud. If correct they move onto the next sequence
whereby another digit is added e.g. 3, 5, 2, 1, 9. This is repeated until they cannot
recall the order correctly.
Fin din gs: Mean span for digits 9.3, mean span for letters 7.3.
Con clusion : These findings suggest that the average capacity in short term memory
is between 5-9 (7+/-2) items.
, Miller ’s findings suggested that the capacity of STM is about 7 items, plus or minus
2. He also noted that people can recall five words as easily as they can recall five
letters. We do this by CH UNK ING.
Evaluation
+ One strength of Jacob’s study is that it has been replicated. The study is a very
old one and early research in psychology often lacked adequate controls. For
example, there was less technology that could’ve helped to standardise the
procedure and eliminate confounding variables (like reading the same digits
at the same speed). Despite this, Jacobs findings have been confirmed by
other, better controlled studies, meaning the conclusion that the capacity of
short term memory is between 5-9 items is consistent and therefore reliable.
This is also a strength because it suggests that Jacobs’ study is a valid test of
digit span and an accurate measure for the capacity of short term memory.
Duration STM - Peterson & Peterson
Aim : To investigate the duration of short term memory.
Sam ple: 24 Psychology student participants completed x8 trials.
Pr ocedur e: Each trial participants were given a nonsense consonant trigram (e.g.
YRT) to remember and a 3 digit number to count backwards from to prevent
rehearsal. The distractor task was necessary as a form of control to stop participants
rehearsing the numbers which would have confounded the results. On each trial they
were told to stop after a different amount of time-E.g. 3, 6, 9, 12, 15 and 18 seconds.
Fin din gs: 80% correct after 3 seconds, 3%- correct after 18 seconds. Concluded that
the duration of the STM was approximately 18 seconds without any verbal rehearsal.
Con clusion : These findings suggest that the duration of short term memory is
limited somewhere between 18-30 seconds.
Evaluation
- One limitation of Peterson and Peterson’s study is that both the setting and
the stimulus material were artificial. Since the study was a laboratory
experiment the environment in which the study took place was very
controlled. Additionally the task itself was regarded as unrealistic. The
procedure gave the participants nonsense trigrams which would not be
reflective of how our memory works on a daily basis as we use our memory (in
reality, we use it for shopping lists rather than random consonants and digits).
The consequence of this is that the findings relating to the duration of short
term memory are not representative of real life settings or tasks. This is a
limitation as it means any conclusions drawn about the duration of the short
term memory cannot be generalised to real life situations or tasks such as
