features of mem stores Flashcards
Capacity of sensory register
large
Duration of sensory register
250ms
Encoding of sensory register
Aucoustic and semantic
Capacity of STM and research
7+/-2
Research: Miller Jacobs
Participants were presented with a sequence of letters or digits containing three items which they had to recall.)
This then increased by one item each time until they could no longer recall the sequence.
Findings:
Average number of items recalled was between five and nine.
Duration of STM
18-30 seconds
Research: Peterson & Peterson
Participants were presented with a trigram (eg- LDI, CTG) which they then had to recall after a delay of 3, 6, 9, 12, 15 or 18 seconds. During the delay rehearsal was prevented by participants counting down from a random number in threes.
Findings:
3 second delay = 90% success.
9 second delay = 20% success.
18 second delay = 2% success.
Encoding of STM
Mainly acoustic
Capacity of LTM
Potentially unlimited
Duration of LTM and research
Potentially a life time
Research: Bahrick
Ex-high school pupils were asked to:
a) Freely recall as many names of people they went to school with as possible.
b) Identify people who they went to school with from a yearbook
Findings:
Participants who were tested within 15yrs of graduation were about 90% accurate in identifying faces. After 48 years, this declined to about 70% for photo recognition. Free recall was about 60% accurate after
Encoding of LTM
Mainly semantic
Encoding research
Research: Baddeley
Participants were given 4 sets of words that were either acoustically similar or acuoustically dissimilar
Participants were also given words that were either semantically similar or semantically dissimilar. Participants then had to recall immediately or after a 20 minute task.
Findings:
Participants had problems recalling acoustically similar words when recalling the word list immediately (from the STM). If recalling after an interval (from LTM) they had problems w semantically similar words
AO3: Features of mem
lim: individual differences
lim: lack ecological validity
lim: baddeley testing
Features of mem lim: individual differences
The capacity of STM is not the same for everyone.
Jacobs also found that recall (digit span) increased steadily with age; eight year olds could remember an average of 6.6 digits whereas the mean for 19 year olds was 8.6 digits. This age increase might be due to changes in brain capacity, and/or to the development of strategies such as chunking.
This suggests that the capacity of STM is not fixed and individual differences may play a role
Features of mem lim: lack ecological validity
Research studies are artificial and lack ecological validity
Eg: Research investigating STM is artificial.
Trying to memorise consonant syllables does not truly reflect most everyday memory activities where what we are trying to remember is meaningful.
However, we do sometimes try to remember fairly meaningless things, such as groups of numbers (phone numbers) or letters (postcodes).
This means that, although the task was artificial, the study does have some relevance to everyday
Features of mem lim: Baddeley
Baddeley’s methodology has been criticised.
May not have tested LTM
In the study by Baddeley, STM was tested by asking participants to recall a word list immediately after hearing it. LTM was tested by waiting 20 minutes. It is questionable as to whether this is really testing LTM.
This casts doubt on the validity of Baddeley’s research because he wasn’t testing LTM after all.
