MEMORY

• displacement


  stm has limited capacity, so any new info will push out what is already there
• short-term memory capacity


  7 (plus or minus 2) items - miller
• short-term memory coding


  acoustic - baddeley
• short-term memory duration


  18-30 seconds - peterson & peterson
• long-term memory capacity


  unlimited
• long-term memory coding


  semantic - baddeley
• long-term memory duration


  up to a lifetime - bahrick
• sensory register capacity


  very high
• sensory register coding


  sense-specific - separate sensory registers for each sense
• sensory register duration


  0.5 seconds - sperling
• sensory register that codes visual info


  iconic store
• sensory register that codes auditory info


  echoic store
• maintenance rehearsal


  repeating sounds or words in a loop to keep them in working memory while they are needed
• retention interval


  period between a participant's exposure to info + being tested for quality of memory for that info
• coding


  the format in which information is converted to and stored in the various memory stores
• acoustic


  by sound
• semantic


  by meaning
• baddeley (coding)


  investigated stm & ltm coding

  - gave different lists of words to 4 groups (acoustically similar / dissimilar, semantically similar / dissimilar)

  - stm recall worse with acoustically similar words (so codes acoustically)

  - ltm recall worse with semantically similar words (so codes semantically)
• baddeley (coding) evaluation - artificial stimuli


  - word lists had no personal meaning to participants

  - meaningful info may be processed semantically even in stm

  - limited application
• capacity


  the amount of info that can be held in a memory store
• jacobs


  - recall 4 digits in right order

  - if correct, 5 digits to recall + so on until they cannot recall digits in correct order

  - determines individual's digit span

  - mean digit span 9.3; mean letter span 7.3
• jacobs evaluation - lacking validity


  - conducted long time ago = lacks temporal validity

  - early research in psych often lacked adequate control, meaning more confounding variables (ie distracted = didn't perform as well)

  - however, later research confirms results, increasing validity
• miller


  investigated capacity of stm

  - found most things come in 7s (ie days of week)

  - suggests capacity for stm is about 7 items, plus/minus 2

  - suggested people do this by chunking, which is grouping sets of digits or letters into units or chunks
• duration


  length of time information can be held in memory
• peterson and peterson


  investigated duration of stm

  - remember trigrams (i.e. ygc) & 3-digit number to count backwards from (prevent mental rehearsal of trigram, which could increase participant's memory of it)

  - tested retention interval, telling participants to stop after different amount of seconds

  - answers less accurate after long retention interval

  - suggests stm has short duration
• bahrick


  investigated duration of ltm

  - photo recognition test: photos from participants' yearbooks

  - free recall test: participants recalled all the names from their class

  - photo recognition = 90% (15 yrs post graduation) & 70% (50 yrs post graduation)

  - free recall = 60% (15 yrs post graduation) & 30% (50 yrs post graduation)

  - shows ltm can last long time
• peterson & peterson overall evaluation


  - meaningless stimuli

  - weak internal validity
• peterson & peterson evaluation - meaningless stimuli


  - stimulus material artificial

  - memorising consonant syllables doesn't reflect real-life memory activities

  - therefore lacked external validity

  - however, we do sometimes try to remember meaningless stimuli, so not completely irrelevant
• spontaneous decay


  automatic fading of memory trace if not rehearsed
• peterson & peterson evaluation - weak internal validity


  - spontaneous decay as alternative explanation

  - another is displacement; participants counted down during retention interval, displacing consonant syllable until needed
• bahrick evaluation - higher external validity


  - real-life, meaningful memories studied

  - other ltm studies that had meaningless pictures = lower recall rates

  - downside is confounding variables not controlled, ie participants may have looked back at yearbook over the years or never spoke to certain people
• atkinson and shiffrin


  multi-store model (msm)
• describe msm

  
• msm overall evaluation


  + research evidence (glanzer and cunitz)

  + case study support (hm & clive wearing)

  - more than one type of stm + ltm

  - more than one type of rehearsal

  - wmm
• sperling


  research evidence for existence of sensory memory

  - grid of digits for 1/2 sec + asked to write all 12 items (sometimes only one row, according to pitch of a tone played after ie high, med, low)

  - if they could recall 3 items, suggests they took in 9+ from whole grid with SR, but decayed faster than they could write

  - suggests SR has short duration + info decays rapidly
• glanzer and cunitz


  research evidence for stm + maintenance rehearsal

  - showed list of 20 words one at a time, then asked to recall the words

  - could recall first and last words best = serial position effect

  - primacy effect (remember first words) & recency effect (remember last words)

  - supports msm: primacy effect from words best rehearsed so transferred to ltm; recency effect because still fresh in stm
• msm evaluation - more than one type of stm and ltm


  - shallice and warrington

  - msm states that ltm + stm are unitary stores, but sutdies with amnesia show this can't be true

  - research shows there to be at least 2 stores; the wmm includes these variations
• msm evaluation - more than one type of rehearsal


  - craik and watkins

  - msm argues what matters in rehearsal is how much you do it; more you rehearse, more likely it will go to ltm

  - serious limitation because its another research finding that cannot be explained by the model
• shallice and warrington


  - studied amnesia patient 'kf'

  - found kf's stm for digits was very poor when they were read out to him, but was much better when he read them himself

  - shows a difference between a visual store vs an auditory store

  - both supports msm but also conflicts as stm is a unitary store in the model when it may have further components (therefore supports wmm)
• craik and watkins


  found what really matters about rehearsal is the type, and identified two types:

  - maintenance rehearsal (described in msm but does not transfer info to ltm, just maintains stm)

  - elaborative rehearsal (needed for long-term storage)