,Capacity ,
duration + coding of memory
Capacity<amount of information that can be held in a memory store Coding : the format in which information is stored in the various memory stores Semantic visual and
,
Capacity of STM : can be assessed using the digit span technique . acoustic
Jacob 1887 used digitS pan technique in his lab experiment to assess the capacity of Semantic-meaning of the word. Lim
Sim .
Found aug span of digits was 9 3 . and 7 3 for letters
.
.
Visual (what the word looks like
Miller 1956 reviewed psychological research + concluded that the span of immediate < what the word
acoustic sounds like Sim
memory is on . He came to this conclusion
average 7 items by observing everyday practises ,
Research : Baddelely 1966 a and 1966b) gave different lists of words to 4 groups of ppts to remember .
3
.g
e
., things come in sevens ,
7 notes on a musical scale ,
7 days of the . He
week etc developed group : acoustically similar words-cat ,
sat , mat ,
cab , can
to test
Sim
the magic 7 or-2' . They chunking digits group : acoustically dissimilar words pit
number + do this by I
grouping sets of or letters -
, few , cow , Cup , egg
3
into chunks
. group 3 : Sematically similar words-great , large , big huge , massive
,
to test
Lim
Evaluation of research on capacity ofS im: group 4 :
Sematically dissimilar words-good , huge , hot , small , cold
Validity of research : Jacobs research is very oldOverestimation of the capacity : Miller may Ppts were shown the original words tasked to recall them in the correct order . When they had
+ the problem with this is the research may lack have overestimated the capacity ofS im .
to do this recall task immediately after hearing it for sim
they tended to do worse with
control . Ppts may not have performed as well as Cowan 2001 reviewed research + found acoustically similar words , suggesting that sim uses an acoustic code
. If ppts were asked
they could've .
E g. , noise
.
may have been a that the capacity of Sim was about 4 to recall the word list after 20 mins for Lim they did worse with the semantically
confounding variable
. chunks
. This suggests that the lower end similar words , suggesting that Lim uses a semantic code
.
However ,
it has been replicated + further Of miller's estimate is more appropriate Evaluation of research on coding In Sim + Lim :
I
I
Studies have confirmed the results of Jacobs to use
. Artificial Stimuli : He used an artificial Separate memory stores : a strength of his
research which gives it's validity . Stimuli rather than meaningful memory. Study is that it identifies a clear difference
Duration < length of time information can be held in memory
. This means it's difficult to generalise the between 2 memory stores
. Important step in
Duration of Sim : is limited to approx . 18-30 seconds . findings to real life situations involving to research has led to the development of
Peterson
+ Peterson 1959 studied the duration of Sim using 24 students
. Each ppts was memor y. the multi-store model of memory.
tested over 8 trails
. On each trial a ppt was a given a consonant syllable + a 3 digit
number e .
g ., THX S12 . They were asked to recall that consonant syllable after a retention
interval of 3 ,6 ,
9 ,
12 , 15 or 18 seconds
. During the retention interval they had to count
backwards from their 3 digit number . After 3 sees , ppts were 90 % correct
. After a sees
,
20 % correct + after 18 sees 2 % were correct .
This suggest the duration of Sim is less
than 18 secs if verbal rehearsal is prevented.
Duration of LTM : is unlimited + potentially a lifetime
Bahrick et al 1975 tested 400 people add 17-74 on their memory of classmates
. A
photo recognition test consisted of 50 photographs some from the schools , high school
. In
yearbook a free-recall test ppts were asked to list the names they could remember
in their graduating class. Pots tested within IS years of graduation were about 90 %
accurate in identifying faces + 60 % accurate on free recall . After 48 years this declined
,
to about 70 % for photo recognition + 30 % on free-recall.
Evaluation of research on duration of STM + LTM :
Artifical Studies : Peterson + Peterson < the External Validity : Bahrick has high external
Stimulus material was artificial + do not reflect validity as real life memories are being
. This
everyday memory tasks I t lacks
means studied.
external validity. However ,
confounding variables can't be
controlled. Bahricks ppts may have looked
in the yearbook or have stayed in touch
with people , meaning they are more likely to
recall correctly.
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