features of memory short term memory Flashcards
what is capacity
the amount of information that can be held in memory
capacity research: Miller’s magic number
magic number 7 plus or minus 2 provides evidence for the capacity of short term memory. most adults can store between 5 and 9 items in their stm. miller thought this because stm only has a certain number of slots where numbers can be stored
millers magic number what is chunking
grouping letters or numbers into units (how we remeber info) eg phone numbers
capacity research: jacobs digit span
he used the digit span test with every letter in the alphabet and numbers apart from w an 7 because they had 2 syllables. he found out people find it easier to recall numbers not letters. average span for letters is 7.3 and numbers is 9.3. this supportsd miller
capacity limitation: cowan
cowan reviewed other research and concluded the capacity of stm is only 4(+/-1) rather than the digit span that jacobs found. lacks validity
capacity strength: jacobs
jacobs used standardised procedures in his research and it took place in a lab setting meaning the study has high levels of control therefore it could be replicated by other controlled studies like bopp and verhagen therefore high reliability
what is duration
the length of time information remains in memory
duration research: peterson and peterson
procedure
the sample was 24 psychology students. they were each given a consonant syllable such as GWN and a 3 digist number such as 538. they had to count back from the 3 digit number until told to stop and had to recall syllable. they were asked to stop after 3,6,9,12,15,18 seconds.
peterson and peterson: results and findings
the longer the delay the less info recalled. after 3 secs average recall was 80%, after 18 seconds it was 3%.
peterson and peterson conclusion
the rapid loss of information from memory when rehearsal is prevented is taken as an indication of short term memory having a limited duration of 15-18 seconds
limitation peterson and peterson: sample
used a small and limited age range sample of just 24 psych students, less representative. as students studied psych they could of fallen to demand characteristics. lacks validty therefore (int)
limitation peterson and peterson: aritifical stimuli
the digits and letters were artificial stimuli. does not represent how we use memory in real life. therefore lacks ecological validity we cannot generalise
strength peterson and peterson
research has standardised procedures in the material used (trigrams and set recall times). it took place in a lab. allowed for high control and replication. therefore high reliability
