Chapter 2- Memory Flashcards
What is the capacity of Sensory Memory.
“Huge”
What is the duration of Sensory Memory
Fraction of a second
Whqt is the encoding of Sensory Memory
Iconic and Echoic
What is the capacity of Short Term Memory (STM)
7 +/- 2 items or chunks
What is the duration of STM?
18-30 seconds without rehearsal
What is the encoding of STM?
Acoustic (sub-vocal)
What is the capacity of Long Term Memory (LTM)
Unlimited
What is the duration of LTM?
Almost a lifetime
What is the encoding of LTM?
Semantically
Who and when made the Multi-Store Model (MSM)?
Atkinson + Shiffrin (‘68-‘71)
Briefly, what is the MSM?
Multi Store Model suggests that memory is made of 3 stores linked by processing. The 3 stores are called:
- Sensory Register
- Short Term Memory
- Long Term Memory
Describe the Sensory Register in the MSM:
- All stimuli from environment pass into sensory register (SR).
- there are 5 senses, but mainly iconic (visual stimuli) and echoic (auditory stimuli)
- type of encoding is modality-specific (level of sensory experience)
- duration of SR is fraction of a second
- SR has very high capacity, info passes only when attention is given.
Describe how STM works in the MSM:
- STM encoded acoustically
- duration is 18-30 secs long (without rehearsal)
- capacity is 7 +/- 2 items/chunks
- with maintenance rehearsal, info moves from STM to LTM
- retrieval is when LTM accesses info from STM
- info enters STM from Sensory Register only when attention is given.
Describe how LTM works in the MSM:
- LTM encodes semantically (has some meaning to person)
- duration of LTM could be up to a lifetime
- LTM capacity is unlimited.
- according to MSM, info we want to recall from LTM has to be transferred back to STM = retrieval.
- prolonged rehearsal in STM leads to info being stored in LTM.
Describe research done on encoding in LTM and STM:
Include APFC.
Baddeley ‘66:
different lists of words to 4 PP groups to remember..
Gr1: acoustically similar
Gr2: acoustically dissimilar
Gr3: semantically similar
Gr4: semantically dissimilar
Recall:
immediately after: PP did worse with acoustically similar
after 20 mins: PP did worse with semantically similar
Conc:
info is encoded acoustically in STM and semantically in LTM.
Describe research done on capacity in STM:
You could use Miller or Jacobs
Jacobs (1887): STM
4 digits read out + PP recalls digits out loud in correct order.
If correct, 5 digits read out + so on until PP cannot recall in correct order. = individual digit span
Findings:
mean span for digits: 9.3 items
mean span for letters: 7.3 letters
Miller (1956): STM
observations made in everyday practise.
-everything came in 7s (days of week, musical scale)
-miller thought span STM = 7 +/- 2 items
-people can recall 5 words as easily as 5 letters
= chunking.
Describe research on duration in STM:
P+P, (1959): STM
- 24 students tested
- 8 trials
- each trial- student given consonant syllable (triads)
- also given 3 digit number
- told to count back from number until told stop (diff. durations)
- prevents mental rehearsal- increase STM duration.
- after 3 secs: avg recall 80%
- after 18 secs- avg recall 3%
- suggests STM duration = approx 18 secs unless verbal rehearsal.
Describe research on duration in LTM:
Bahrick et al. (1975): LTM
- 392 American PPs (aged 17-74)
- highschool yearbooks obtained from PPs
Types of recall:
- photo-recognition - 50 photos
- free recall test - recalled names
Findings in photo reco:
PPs tested within 15yrs: 90% accurate in photo reco
PPs tested after 48 yrs: recall fell to 70% photo reco
Findings in free recall:
- after 15 yrs: 60% accurate recall of names
- after 48 years: 30% accurate recall of names
Suggests LTM may last up to lifetime for some material.
Evaluate Baddeley’s study of LTM+STM:
Good:
identified clear diff. between 2 memory stores and…
STM = acoustic encoding
LTM: semantic encoding
these findings stood the test of time!
helped make MSM
Bad:
Artificial Stimuli- not meaning material = lacks mundane realism
word list no meaning to PP- not representative of real life
Baddeley findings may not tell much about coding in STM or LTM
could be semantic for STM too.
Suggests findings have limited application.
Evaluate Jacobs study of STM:
Good:
has been replicated
old studies often lack controls- confounding variable presence.
Despite this, Jacobs findings confirmed by Bopp+Verhaeghen 2005 (more controlled)
Evaluate Miller’s Study of STM:
Bad:
overestimated STM capacity
Cowan 2001 reviewed other research
concluded capacity STM is only about 4 +/- 1 chunks
Suggests lower end of Miller Research is accurate, findings more appropriate than 7 items.
Evaluate Peterson and Peterson Study of STM:
Bad:
artificial stimuli material
study isn’t completely irrelevant because sometimes we DO remember fairly meaningless materials
BUT recalling consonant syllables does NOT reflect everyday memory (semantically)
Study lacks external validity
Evaluate Bahrick et al. study of LTM:
Good:
High External Validity
-researchers investigated meaningful memories
-when studies conducted expt w/ meaningless pic, recall fell (Shepard 1967)
-Suggests Bahrick findings reflect realer estimate of duration LTM.
Use the Case Study of HM to evaluate MSM:
-HM underwent brain surgery to relieve epilepsy.
-Procedure was not well understood.
-Hippocampus (central to memory function) removed from both sides of brain.
-HM’s memory assessed 1955, HM thought it was 1953 and thought he was 27 y/o (in reality was 31 y/o)
-little recall of operation
-could not form LTMs
-would read same magazine repeatedly w/o remembering it.
HOWEVER
-he performed well on tests of immediate memory span- measure of STM
= good support of MSM, separate memory stores that work independently and interconnect. Evidence for MSM.