coding, capacity & duration of memory Flashcards
coding for STM
acoustic (sounds) - mainly
coding for LTM
semantic (meaning) - mainly
capacity of STM
5 to 9
duration of STM
approx. 18 seconds
capacity of LTM
unlimited
duration of LTM
whole lifetime (limitless)
who conducted the research on coding
Baddeley - 1966
describe the research on coding by baddeley 1966
- different lists of words to 4 groups:
- 1 (acoustically similar)
- 2 (acoustically dissimilar)
- 3 (semantically similar)
- 4 (semantically dissimilar)
- participants shown original words & asked to recall in correct order
= done immediately (STM) = worse in acoustically similar
= done after time interval (20 min) = worse in semantically similar
what does Baddeley’s (1966) research suggest
STM is coded acoustically
LTM is coded semantically
which 2 researchers conducted the research on capacity
Jacobs (1887)
Miller (1956)
describe Jacobs (1887) research on capacity
- measured digit span
eg. reads out 4 digits & participant recalls these out loud in correct order - if these are correct, the researcher reads out 5 digits etc.
Jacobs (1887) results
mean span for digits was 9.3
mean span for letters was 7.3
describe Millers (1956) research on capacity
- span of memory and chunking
- made observations of everyday practice
eg. he noted things that come in sevens - thought that span of STM is 7 items +- 2
- noted people remember 5 words as easily as 5 letters - do so by chunking
who researched the duration of the STM
Peterson & Peterson (1959)
describe the research of duration of the STM
- tested 24 students in 8 trials
- each trial: student given consonant syllable to remember & 3-digit number
- student counted back from this number until told to stop (stop mental rehearsal)
- each trial: told to stop after varying amounts of time eg. 3-18 secs (up in 3s)
results of Peterson & Peterson (1959) study
- after 3 secs = avg. recall at 80%
- after 18 secs = avg. recall at 3%
who researched the duration of LTM
Bahrick et al. (1975)
describe the research on the duration of LTM
- 392 american participants aged 17-74
used yearbook in 2 groups:
1) photo-recognition of 50 photos - some from yearbooks
2) free recall test of all names in graduating class
results of research on duration of LTM
- after 15 years of graduation = 90% accurate in photo recognition & 60% in free recall
- after 48 years = 70% for photo recognition & 30% for free recall
evaluation of research on coding - AO3
+)
P: baddeleys study identified clear difference between 2 memory stores
E: coding for STM is acoustic & LTM is semantic
T: important understanding that led to the multi store model
-)
P: baddeleys study used artificial stimuli
E: word lists had no personal meaning to participants - findings may not tell us about coding in everyday memory tasks (people may use semantic coding for meaningful material in STM)
T: findings have limited application
evaluation of research on capacity - AO3
+)
P: jacobs study has been replicated
E: an old study and early research that may have lacked adequate control eg. some digit spans may be underestimated as individual was distracted during (confounding variable) but the results have been confirmed by other studies (eg. Bopp and Verhaeghen 2005)
T: study is a valid test of digit span in STM
-)
P: millers research may have overestimated STM capacity
E: Nelson Cowan (2001) reviewed other research & concluded capacity of STM is only 4+/-1 chunks
T: lower end of Millers estimate is more appropriate than 7
evaluation of research on duration - AO3
+)
P: bahrick et. al’s study had high external validity
E: investigated meaningful memories (peoples names/faces) & when testing meaningless material recall rates were lower (eg. Shepard 1967)
T: results show more ‘real’ estimate of duration of LTM
-)
P: peterson & peterson’s stimulus material was artificial
E: recalling constant syllables doesn’t reflect most everyday memory activities
T: lacks external validity
