STM & LTM

• How does the capacity of short-term memory (STM) compare to long-term memory (LTM)?

  STM has limited capacity; LTM is infinite
• How can the capacity of STM be assessed?

  Using digit span studies
• What did Miller (1956) conclude about STM capacity?

  7 +/- 2 items
• What happens to recall accuracy as the number of dots increases in Miller's study?

  Accuracy decreases with more dots
• How many letters can people typically recall using chunking?

  Five letters
• What is the duration of STM without rehearsal?

  Less than 18 seconds
• What did Peterson and Peterson (1959) find about recall accuracy after 3 seconds?

  90 percent correct recall
• What was the recall accuracy after 18 seconds in Peterson and Peterson's study?

  2 percent correct recall
• What did Bahrick et al (1975) study in relation to memory?

  Photo-recognition of former classmates
• What was the accuracy of recalling names within 15 years of graduation according to Bahrick et al (1975)?

  90 percent accuracy
• How did recall accuracy change after 48 years according to Bahrick et al (1975)?

  Declined to 70 percent
• What was the free recall accuracy after 15 years in Bahrick et al's study?

  60 percent accurate
• What was the free recall accuracy after 48 years according to Bahrick et al (1975)?

  30 percent accurate
• What does coding refer to in memory?

  How information is changed for storage
• How is STM primarily encoded?

  Acoustically (in sounds)
• How is LTM primarily encoded?

  Semantically (in meanings)
• What did Baddeley (1966) find about recall in different groups?

  Group A had worst recall in STM
• Which group had the worst recall in LTM testing according to Baddeley (1966)?

  Group C (semantically similar words)
• What are the key points regarding the capacity of STM?

  • STM is limited to 7 +/- 2 items (Miller)
  • Cowan suggests it may be 4 chunks
  • Chunk size affects memory span (Simon, 1974)
• What are the key points regarding the duration of STM?

  • Duration is less than 18 seconds without rehearsal
  • Peterson and Peterson found 90% recall after 3 seconds
  • Recall drops to 2% after 18 seconds
• What are the key points regarding the duration of LTM?

  • LTM can potentially last forever
  • Bahrick et al found 90% accuracy within 15 years
  • Accuracy declines to 70% after 48 years
• What are the criticisms of STM research?

  • Miller's findings lack replication
  • Research often uses artificial tasks
  • Peterson and Peterson's study may involve displacement