Memory : Coding, capacity and duration Flashcards
what is it? coding, capacity and duration
outline short-term memory
limited-capacity memory store
coding mainly acoustic
capcity between 5 and 9 items on average
duration about 18 seconds
what is it? coding, capacity and duration
outline long-term memory
permanent memory store
coding mainly semantic
unlimted capacity + can store memories for up to a lifetime
define ‘coding’
the format in which information is stored in various memory stores
define ‘capacity’
the amount of information that can be held in a memory store
define ‘duration’
the length of time information can be held in memory
what year did Alan Baddeley’s study take place?
1966
what lists of words were each of the four groups given (Baddeley)
group 1 - acoustically similar
group 2 - acoustically dissimilar
group 3 - semantically similar
group 4 - semantically dissimilar
what were the findings of Baddeley’s study?
when recalling from STM, participants did worse with words acoustically similar
when recalling from LTM, participans did worse with words semantically similar
what do the findings of Baddeley’s study suggest?
information is coded acoustically in short-term memory and semantically in long-term memory
outline one strength of Baddeley’s study
clear difference between memory stores identified
later research shown some exceptions to findings but idea that STM uses mostly acoustic coding and LTM mostly semantic remains
important step in understanding of memory sytems, led to multi-store model
outline one limitation of Baddeley’s study
artificial stimuli used
word lists held no meaning to participants
findings may not tell much about coding in memory tasks especially in everyday life
findings have limited application
what year was Jacobs’ study conducted?
1887
what was the mean span Jacobs’ found for letters?
7.3
what was the mean span for digits Jacobs’ found?
9.3 items
outline a strength of Jacobs’ study
study replicated
old study, early psychological research lacked adquate controls
ex. some participants digit spans may have been underestimated because of distractions whilst testing [confounding variables]
despite this Jacobs’ findings hav been confirmed in other studies
suggests study valid test of digit span in STM
what year was Miller’s study conducted?
1956
what did Miller do?
made observations of everyday practice e.g things that come in 7s
noted people can recall 5 words as easily as they can 5 letters
this is done by chunking (grouping sets of digits or letters into units or chunks)
outline one weakness of Miller’s study
ovestimation of STM capacity
Cowan, 2001-> reviewed other research and concluded capacity of STM is only about 4+/-1 ratheer than 7+/-2
suggests lower end of Miller’s estimate is more appropriate
(5 rather than 7)
what did Jacobs do?
researcher read out 4 digits + particpants recalled them out loud in correct order
amount of digits read out increased until they couldn’t be recalled correctly
this indicates individual’s digit span
what year did Peterson & Peterson’s study take place?
1959
what did Peterson & Peterson do?
tested 24 students in 8 trials
particpants given consonant syllable + 3 digit number to remember
told to count backward to number (to prevent mental rehearsal of syllable) until instructed to stop
time until they were told to stop differed by trial
what were the findings of Peterson & Peterson’s study?
after 3 seconds, average recall about 80%
after 18 seconds, 3%
what did Peterson & Peterson’s study suggest?
STM duration may be about 18 seconds unless information rehearsed
outline one limitation of Peterson & Peterson’s study
artifical stimuli
recalling consonant syllables doesn’t reflect most everyday memory activities where what we are trying to remember is meaningful
study lacked external validity
what year did Bahrick et al’s study take place?
1975
what did Bahrick et al. do?
studied 392 American students aged 17-74
tested recall by:
photo recongnition test consisting of 50 photos, some from yearbooks
free recall test, participants named peers from graduating class
what were the findings of Bahrick et al.’s study?
participants tested within 15 years of graduating were about 90% accurate in photo recognition
after 48 years, dropped to 70%
free recall less accurate - about 60% after 15 years, halved after 48
what did Bahrick et al.’s study show?
LTM may last up to a lifetime for some material
outline one strength of Bahrick et al.’s study
high external validity
researchers investigated meaningful memories
when studies on LTM conducted with meaningless stimuli, recalll rates lower [Shepard 1967]
suggests findings refelect more ‘real’ estimate of LTM duration
