Memory - coding, capacity and duration Flashcards
What is short term memory?
The limited-capacity memory store
Coding is mainly acoustic (sounds)
Capacity is between 5 and 9 items
Duration is about 18 seconds
What is long term memory?
The permanent memory store
Coding is mainly semantic (meaning)
Capacity is unlimited
Can store memories for up to a lifetime
What is coding?
The format in which information is stored in the various memory stores
What is capacity?
The amount of information that can be held in a memory store
What is duration?
The length of time information can be held in the memory
Coding - Baddeley, Acoustic and semantic
What was the procedure?
Acoustically similar words (e.g cat cab can) or dissimilar (e.g pit few cow)
Semantically similar words (e.g great large big) or dissimilar (e.g good huge hot)
Coding - Baddeley, Acoustic and semantic
What are the findings?
Immediate recall was worse with acoustically similar words, STM is acoustic
Recall after 20 minutes worse with semantically similiar words, LTM is semantic
Capacity - Jacobs, Testing digit span
What was the procedure?
Researcher reads four digits and increases until the participant cannot recall the order correctly
Capacity - Jacobs, Testing digit span
What are the findings?
On average participants could repeat back 9.3 numbers and 7.3 letters in the correct order immediately after they were presented
Capacity - Miller, Magic number 7+_2
What was the procedure?
Miller observed everyday practice, noted that things come in sevens
Capacity - Miller, Magic number 7+_2
What are the findings?
The span of STM is about 7 items (plus or minus 2) but is increased by chunking - grouping sets of digits/letters into meaningful units
Duration STM - Peterson and Peterson, Consonant syllables
What was the procedure?
24 students were given a consonant syllable to recall and a 3 digit number to count backwards from
The retention interval was varied: 3, 6, 9, 12, 15 or 18 seconds
Duration STM - Peterson and Peterson, Consonant syllables
What are the findings?
After 3 seconds - average recall was about 80%.
After 18 seconds it was about 3%
STM duration without rehearsal is up to 18 seconds
Duration LTM - Bahrick et al, Yearbook photos
What was the procedure?
Participants were 392 Americans aged between 17 and 74
1) Recognition test - 50 photos from high school yearbooks
2) Free recall test - Participants listed names of their graduating class
Duration LTM, Bahrick et al, Yearbook photos
What are the findings?
Recognition test - 90% accurate after 15 yrs, 70% after 48 yrs
Free recall test - 60% recall after 15yrs, 30% after 48 yrs
What is a strength and limitation of Baddeley’s study?
Strength - Identified two memory stores
Limitation - Study used artificial stimuli
One strength of Baddely’s study is that it identified two memory stores….
Later research showed that there are expections to Baddeley’s findings
But STM is mostly acoustic and LTM is mostly semantic
Lead to the development of the Multi Store Model
What is a strength of Jacob’s study?
It has been replicated
One strength of Jacob’s study it that it has been replicated….
This is an old study and may have lacked adequate controls (confounding variables e.g participants being distracted)
Despite this, the findings have been confirmed in later controlled studies
Showing study is valid measure of STM digit span
What is a limitation of Miller’s research?
It may overestimate STM capacity
One limiaiton of Miller’s research is it may overestimate STM capacity……
For example Cowan reviewed other research
Concluded that the capacity of STM was only about 4 (plus or minus 1) chunks
Lower end of Miller’s estimate (5 items) is more appropiate than 7 items
What is a limiation of Peterson and Peterson’s study?
Meaningless stimuli
A limitation of Peterson and Peterson’s study is meaningless stimuli…..
Sometimes recall meaninglessthings so the study is not completely irrelevant
Recall of consonant syllables does not reflect meaningful everyday memory tasks
Study lacked external validity
What is a strength of Bahrick’s study?
High external validity
One strength of Bahrick’s study is it had high external validity…
Everyday meaningful memories e.g peoples faces and names, were studied
When lab studies were done with meaningless pictures to be remembered, recall rates were lower
Bahrick’s findingd reflect a more ‘reak’ estimate of the duration of LTM
