Short and long term memory

• What is meant by capacity?

  Measure of how much can be held in memory
• What is meant by coding?

  The way info is changed so it can be stored in memory
• What is meant by duration?

  Measure of how long a memory lasts before it’s no longer available
• What is meant by LTM

  memory for events that have happened in the past
• What is meant by STM?

  Memory for immediate events
• State the capacity of STM and how it was investigated, and who investigated it

  • 7+/-2 (5-9 items) (George Miller)
  • Digit span technique used to investigate
  • Investigated by Jacobs
  • Jacobs found that memory was 9.3 items and 7.3 letters on average
• Evaluate capacity for STM

  • Individual differences- capacity isn’t the same for everyone, differs with age
  • Size of the chunk matters- people have a shorter memory for larger chunks, supports view that STM has limited capacity
• Describe the study for duration of STM

  • Peterson and Peterson
  • Consonant syllable and 3 digit number
  • recall consonant syllable after retention interval of 3,6,9,15,18 secs
  • Had to count backwards from three digit number during retention interval
  • 90% correct after 3s
  • 20% after 9s
  • 2% after 18s
  • STM= 18-30s
• Describe the study of duration for LTM

  • Bharik et al
  • 400 ppl of ages 17-74
  • Photo recognition test- within 15 yrs of graduating- 90% accuracy, after 48 yrs- 70% accuracy
  • Free recall of ppl they remembered in HS - 60% accurate after 15 yrs, 30% after 48 yrs
  • Duration is potentially forever
• Evaluate duration

  • Lab studies- artificial, low ecological validity, hard to generalise to realistic situations
  • High internal validity- lab study, causal relationships can be identified
• Describe the study for coding in STM

  • Baddeley
  • Recalling a list of words
  • 2 lists- acoustically similar, semantically different, and semantically similar, acoustically different
  • STM test- recall 12 sets of 5 words immediately
  • Result- there was difficulty in recalling acoustically similar words in STM. Therefore STM codes acoustically
• Describe the study for coding in LTM

  • Baddeley
  • Recalling a list of words
  • 2 lists- acoustically similar, semantically different, and semantically similar, acoustically different
  • LTM test- 10 words listed, recalled 20 mins later
  • Result- difficulty remembering semantically similar words. Therefore LTM codes mainly semantically
• Evaluate coding

  • Baddeley may have not been testing LTM- only recalled words 20 mins after they were learned- unsure whether this is really testing LTM- duration period of LTM is subjective
  • Lab study- high internal validity but low ecological validity- can identify causal rels but may not be able to extrapolate
• Describe the study for capacity of the sensory register

  • Sperling
  • Pps presented with 3x4 grid of letters
  • 4/5 letters recalled but pps remembered seeing more, so study adapted so tone was sounded to recall a specific row
  • Recall= 100% accurate
  • Capacity is large
• what’s the duration of the sensory register?

  About 500 ms (Walsh and thompson)
• Coding of the sensory register?

  • Olfactory
  • Gustatory
  • Echoic
  • Iconic
  • Haptic