memory - models of memory Flashcards
define coding
the way information is changed so that it can be stored in the memory
3 main ways that information can be encoded:
1) visual (picture)
2) acoustic (sound)
3) semantic (meaning)
define capacity
how much info can be stored
define duration
the period of time information can last in the memory stores
what is short term memory (STM)?
your memory for events in the present or immediate past
what is long term memory (LTM)?
your memory for events that have happened in the more distant past
why can’t we ask people what codes they are using?
coding happens unconsciously
how does the STM code and how do we know?
acoustically → baddeley’s research
when did baddley’s research occur?
1966
the aim of baddley’s research into STM
to examine whether coding in STM is primarily acoustic or semantic
what procedure did baddley use when investigating STM?
-75 participants were divided into 4 groups
-each group heard a list of five words drawn from one of the following categories
(acoustically similar words, acoustically dissimilar words, semantically similar words, semantically dissimilar words)
-immediately after hearing the 5 words they were asked to recall them in the correct order
-this procedure was repeated 4 times
findings of baddeley’s research into STM
-participants given acoustically similar words performed the worst, with a 55%
accuracy
-they confused similar sounding words,
-semantically similar lists only produced a slight detrimental effect
conclusions from baddeley’s research into STM
since acoustically similar words were recalled the least efficiently, it
seems there is acoustic confusion in STM
-suggesting STM is coded acoustically
how does the LTM code and how do we know?
semantically → baddeley’s research
the aim of baddley’s research into LTM
to examine whether coding in LTM is primarily acoustic or semantic
what procedure did baddley’s use while investigating LTM?
-same procedure as his original study, but instead gave his participants a 20-minute interval before recall (now testing LTM)
-during the interval, they conducted another task
findings of baddeley’s research into LTM
-it was found that participants with semantically similar words performed the worst and had only 55% recall
-recall for other lists was 70-85%
conclusions from baddeley’s research into LTM
-there is semantic confusion in LTM
-suggests that LTM is encoded semantically
evaluations of baddeley’s research:
-good validity
-meaningful material was not used
-baddeley may not have tested LTM
ao3 baddeley’s research: good validity
P - a strength of Baddeley’s research into coding is that it has good validity
E - word length was standardised which eliminated some extraneous variables
↳ this allows us to establish cause and effect as we can be more certain that it is the changes in the types of words affecting recall and no other
factor
L - increases the internal validity of
baddeley’s findings into the coding in
memory
ao3 baddeley’s research: meaningful
material was not used
P - limitation of baddeley’s study is that meaningful material was not used
E - the words used in the study had no
personal meaning to participants
↳ this means that baddeley’s findings might not tell us much about coding in everyday life
↳ for example, people tend to use semantic coding even for STM tasks as they have a reason for trying to remember it (e.g. a shopping list)
ao3 baddeley’s research: baddeley may not have tested LTM
P - baddeley may not have tested LTM
E - in the study, STM was tested by asking participants to recall a word list immediately after hearing it, LTM was tested by waiting 20 mins
↳ it is questionable whether this is really testing LTM
L - this casts doubt on the findings of the research into the coding of short and long term memory
what is the capacity of the STM and how do we know?
limited capacity, we can hold only a small amount of information before it is forgotten → jacobs/miller
when did jacobs carry out his research?
1887
who did jacob’s use in his study?
jacobs used a sample of 443 female students from the north london collegiate school
what procedure did jacob’s use to investigate the capacity of the STM?
-jacobs used a digit span test, to examine the capacity of STM for numbers and letters
-he read a list of either letters or numbers, with one syllable (‘w’ and ‘7’ were excluded)
-participants had to repeat back a string of numbers or letters in the same order and the number of digits/letters was gradually increased, until the participants could no longer recall the sequence
what were the findings of jacob’s research into STM?
-jacobs found that STM capacity for digits was 9 (9.3), whereas letters was 7 (7.3)
conclusion of jacob’s research into STM
-STM has a limited capacity of 5-9 digits and that numbers were easier to recall than letters
what happens when new info comes into the STM?
the STM pushes out the old information (displacement) due to its limited capacity
when did miller carry out his research?
1956
miller’s observations
-miller made observations of everyday practice
-he noted that things come in sevens: seven notes on the musical scale, seven days of the week, seven deadly sins
-miller thought that the capacity of STM is about 7 items, plus or minus 2
miller’s magic number
7 plus or minus 2
how did miller demonstrate his observations?
-he read list of digits to participants who immediately had to repeat back each list
in the right order
-the list increased in length 1 digit at a time – the maximum number of digits that could be recalled in the correct order is your immediate memory span
miller and chunking
-miller also noted that people can recall 5 words as easily as they can recall five letters through chunking (grouping sets of digits or letters into chunks)
-even though we can group individual
letters/number/notes to chunks, Miller argued we can still only hold 7+-2 ‘chunks’ of items
-a chunk of information such as an acronym or a date is equal to 1 piece of information
what is the capacity of the LTM and how do we know?
-unlimited capacity
-we know that our brains are not full of information
strengths & weaknesses of jacob’s research
-it was conducted a long time ago
-lack of meaningful material
-biased sample
-syllables were controlled
ao3 jacob’s study: it was conducted a long time ago
P - limitation is that it was conducted a long time ago
E - early research in psychology often lacked adequate controls of extraneous variables
↳ eg: some participants may have been
distracted while they were being tested so they didn’t perform as well
L - this could mean that the results into the capacity of STM may not be valid because there were confounding variables
C - other research, has been able to
replicate digit span studies in more controlled conditions
↳ this suggests that jacob’s and miller’s
study is a valid test of digit span on STM increasing the internal validity of the findings
evaluation of miller’s research
-miller’s research may have overestimated the capacity of STM
-the capacity of STM is not the same for everyone
ao3 miller’s study: miller’s research may have overestimated the capacity of STM
P - a limitation of miller’s research is it may have overestimated the capacity of STM
E - cowen (2001) 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 7 items
↳ although miller’s (1956) theory is supported by psychological research, he did not specify how large each ‘chunk’ of information could be and therefore we are unable to conclude the exact
capacity of STM
L - consequently, further research is required to determine the size of information ‘chunks’ to understand the exact capacity of STM
ao3 miller’s study: the capacity of STM is not the same for everyone
P - the capacity of STM is not the same for everyone
E - jacobs also found that recall in the digit span test increased steadily with age
↳ 8 year olds could remember on average 6.6 digits whereas the mean for 19 year olds was 8.6
↳ this age increase may be due to an increase in brain capacity or that as you get older you develop strategies to improve digit span such as chunking
what is the duration of STM and how do we know?
limited (about 18 secs) → peterson & peterson
when was peterson and peterson’s study conducted?
1959
the aim of peterson & peterson’s study into STM
to test how long the STM lasts when rehearsal is prevented
who did peterson & peterson use in their study into STM?
they used 24 university students to participate in their study
what procedure did peterson and peterson use to study STM?
-participants were shown a
trigram (consonant syllables) and asked to remember it,
-the trigrams were briefly presented to them
-after each trigram participants heard a number and had to count backwards in 3s to prevent them from rehearsal
-counting stopped after a number of time periods (3,6,9,12,15 or 18 seconds) -then participants had to try and recall
the trigram
-this was repeated a number of times using different trigrams
why were consonants chosen?
the inclusion of vowels might have made the trigrams seem more word like, it is important that they are completely meaningless to the participant so they could not use their LTM (eg: BBC)
findings of the peterson and peterson study into STM
-about 80% of the trigrams were correctly recalled after a 3
second retention interval
-dropping to 30% after 9 seconds
-3% after 18 seconds
conclusion of peterson and peterson’s study into STM
if verbal rehearsal is prevented information, information lasts in STM for 18 seconds
strengths and weaknesses of peterson2 study into STM duration
-it was carried out in a laboratory setting
-lacks external validity
ao3 peterson’s study: it was carried out in a laboratory setting
P - one strength of peterson and peterson’s study is that it was carried out in a laboratory setting
E - laboratory settings allows researchers to isolate the IV (trigram) and DV (recall) to test the duration of STM and remove possible extraneous elements variables (rehearsal) which would have influenced
participant’s recall of the trigram
↳ this tightly controlled procedure enabled researchers to find causal links between variables which can provide general laws of the duration of STM
L - we can replicate the research to check for reliability. this increases the validity of the research into the duration of STM
ao3 peterson’s study: lacks ecoval
P - this method can be criticised for
lacking external validity
E – laboratory settings are very artificial in terms of the setting (controlling the IV and EVs) and the task
↳ if participants were asked to
remember everyday items like a shopping list, the duration of STM may be different
L –this research does not allow us to test
our STM in everyday situations which reduces the overall ecological validity of the study into the duration of STM
what is the duration of the LTM and how dw we know?
unlimited/lasts as long as we live → bahrick at all
what was the aim of bahrick at al’s research into LTM duration?
-establish the existence and duration of the LTM
-to see if there is any difference between recognition and recall
who was used in bahrick at al’s study?
graduates from a high school in america
what procedure was used during bahrick at al’s study into the duration of the LTM
-investigators tracked down graduates from a high school in america over a 50 year period
-392 graduates were shown photos from their school yearbook
-participants were aged between 17 and 74
-the time of graduation varied between 2 weeks to 57 years
they were split into 2 groups:
group 1 (recognition group) they were given a picture and a list of names, they had to select the correct name
group 2 (recall group) Asked to name the participants without the list of names
results of bahrick at al’s study
group 1:
recognition of names and pictures and matching of names and pictures all remained high (90%) dropping to 70% after 48 years
group 2:
free recall was less accurate than recognition – 70% accuracy after 3 months, about 60% after 15 years, dropping to 30% after 48 years
