Psychology - memory

• capacity


  amount of info that can be stored in the memory at any one time
• duration


  length of time it can be stored
• encoding


  way the info/memory is stored (E.G. visual/acoustic/semantic)
• sensory memory

  capacity: very large

  duration: milliseconds

  encoding: mainly visual, can be sound and touch
• short-term memory (STM)

  capacity: 7+/-2 (miller)

  duration: 18-30 seconds (peterson and peterson)

  encoding: acoustic (baddeley)
• long-term memory (LTM)

  capacity: huge

  duration: a life-time (bahrick)

  encoding: semantic (baddeley)
• Sensory memory


  Studied by Sperling (1960)
• Sperling's study of sensory memory for vision


  1. Flashing an image on a screen for a very brief instance

  2. Participants asked to remember as many letters as possible from a grid of 12 letters (displayed for 50ms)

  3. Participants could typically only recall around 4 letters before the grid faded from their memory
• Sperling's study of sensory memory capacity


  • Trained participants to distinguish the difference between three tones (high, medium and low)
  • Exposed the same grid for 50ms
  • When the grid disappeared a tone was sounded which corresponded to the row on the grid (top=H, middle=M, bottom=L)
  • Recall was on average around 3 out of 4 symbols from any row
  • Suggests that the iconic store can retain approximately 76% of all data received
• Sperling's study of sensory memory duration


  • If there was a delay between the showing of the grid and the sounding of the tone, more and more info was lost (50% available after 0.3 sec delay and only 33% after 1 sec delay)
• STM - capacity(miller)


  miller found that the capacity was 7+/-2: (5-9)

  • used digit spans to test how many digits could be memorised at one time
  • numbers of increasing lengths were read out to P's for them to read them back until they made a mistake
• how to increase the capacity of STM

  • chunking: grouping letters or numbers together (remember 5-9 chunks)
  • rhythmic grouping: grouping numbers together rhythmically (phone number)
  • utilising our LTM
• STM - duration (peterson and peterson) - aim

  • aim: to test how long STM lasts when rehearsal is prevented
• STM - duration (peterson and peterson)- procedure


  procedure:

  • P's were briefly shown a consonant trigram (3 letters)
  • P's were asked to count backwards in multiples of 3 from a specified number to stop them rehearsing the letters.
  • after intervals of 3,6,9,12,15 or 18 seconds, P's were asked to recall the trigram
  • this was repeated several times using different trigrams
• STM - duration (peterson and peterson)- findings

  findings:

  • P's were able to recall about 80% of trigrams after a 3 sec interval
  • as the time of intervals increased then the amount of trigrams P's were able to recall decreased
  • after 18 secs, fewer than 10% of trigrams were recalled correctly
• STM - duration (peterson and peterson)- conclusion

  conclusion:

  • our STM duration is 18-30 secs
• STM - duration (peterson and peterson)- evaluation

  evaluation:

  • lacks ecological as given an artificial task
  • possible that interference from previous trigrams caused the poor recall
• STM - duration (peterson and peterson)- critical evaluation

  critical evaluation:

  • used standardised procedure
  • reliable as it is scientific and can be replicated
  • lacked mundane realism and external validity
  • only considered STM duration for one type of stimuli
• STM - encoding (baddeley)- aim


  aim: to explore the effects of acoustic and semantic encoding in STM
• STM - encoding (baddeley)- procedure


  procedure:

  • P's were divided into 4 groups, each group heard a list of 5 words drawn from of the following categories:

  1. acoustically similar words (man, mad, map)
  2. acoustically dissimilar words (pen, day, few)
  3. semantically similar words (great, big, large)
  4. semantically dissimilar words (hot, old, late)

  • immediately after hearing the words they were asked to recall them in the correct order
  • this was carried out 4 times
• STM - encoding (baddeley)- findings

  findings:

  • acoustically similar words had 55% recall accuracy and acoustically dissimilar words had 75% recall accuracy
  • similarity of meaning had only a very slight detrimental effect
  • effects of acoustic similarity disappeared when P's long-term learning was tested. this suggests a major factor affecting encoding is whether items are being sorted into STM or LTM
• STM - encoding (baddeley)- conclusion

  conclusion:

  • findings support conrad:

  1. STM relies more on sound of words than their meaning, showed through the difficulty P's had in recalling acoustically similar words
• STM - encoding (baddeley)- evaluation

  Evaluation:

  • the use of the experimental method allows a causal link between the type of coding used in STM and the accuracy of recall.
  • may be to reductionist
• STM - encoding (conrad)

  • looked at whether people used acoustic encoding even when info was provided visually
  • P's shown random sequence of 6 consonants rapidly
  • strings of consonants where either acoustically similar or dissimilar
  • asked to right down letters in the order they appeared
  • most errors made involved substitution of similar sounding letters
  • more difficult to remember acoustically similar letters
  • concluded that items are stored in the STM in some form of acoustic code
• STM - encoding (brandimonte)

  • under some circumstances visual encoding is the superior method
  • P's presented with 6 line drawings of familiar objects and asked to memorise them in order
  • P's asked to form mental image of each one in turn to subtract a specified part of drawing
• LTM - duration (bahrick)- aim

  aim: to establish the existence of very long-term memory to see whether there was any difference between recognition and recall
• LTM - duration (bahrick)- procedure

  procedure:

  • tracked down graduates from a particular high school in america over a 50-year period
  • 392 graduates were shown pictures from their high-school yearbook
  • recognition group: for each photo, P's given a group of names and asked to select the name that matched the photo.
  • recall group: P's asked to name the people in the photos without being given a list of possible names
• LTM - duration (bahrick)- findings

  findings:

  recognition group:

  • 90% correct after 14 years
  • 80% correct after 25 years
  • 75% correct after 34 years
  • 60% correct after 47 years

  recall group:

  • 60% accurate after 7 years
  • less than 20% accurate after 47 years
• LTM - duration (bahrick)- conclusions

  conclusions:

  • people can remember certain types of info for almost a lifetime
  • very long-term memory seems to be better when measured by recognition tests
• LTM - duration (bahrick)- evaluation

  evaluation:

  • ecological validity as uses meaningful stimulus material and tested people on memories of their own lives
  • unclear whether the drop off in accuracy reflects the limits of duration or a general decline in memory with age
• LTM - encoding (baddeley) - aim and procedure

  • focuses on the semantic part of the study for LTM (aim and procedure are the same)
• LTM - encoding (baddeley)- findings

  findings:

  • semantically similar words had 55% recall accuracy
  • semantically dissimilar words had 85% recall accuracy
  • recall was the same for acoustically similar and dissimilar words
• LTM - encoding (baddeley)- conclusion

  conclusion:

  • LTM mainly makes use of semantic coding
• LTM - encoding (baddeley)- evaluation

  evaluation:

  • use of the experimental method allows a causal link between the type of coding used in LTM and accuracy of recall
• multi-store model of memory - atkinson and shiffrin

  
• MSM (AO1)


  Model of memory proposed by Atkinson and Shiffrin
• Stages of MSM


  1. Sensory memory

  2. Short-term memory (STM)

  3. Long-term memory (LTM)
• Information passes through the stages of MSM in a linear fashion
• Sensory memory


  External stimuli enters in an uncoded form
• Attention


  • Vital for information to pass from sensory memory to STM