capacity

• Jacobs digit span test - procedure

  said 4 letters and asked ppts to repeat

  if correct said 5 letters and asked ppts to repeat until ppts could no longer remember correctly
• Jacobs digit span test - findings

  found mean span of digits to be 9.3 items

  found mean span of letters to be 7.3 items
• memory span - Miller 


  STM span is 7 + _ 2 digits

  (9-5 digits)
• chunking - Miller 


  found that people can remember 5 words as well as 5 letters through chunking
• valid study - Jacobs

  P: strength - jacobs sudy has been replicated

  E: in original study, ppts capacity may be over estimated due to distractions (confounding variables)

  E: however, Jacobs finding have been confirmed by other, better controlled research

  L: therefore Jacobs experiment is a valid study
• overestimated chunking - Miller 


  P: limitation - overestimated chunking

  E: researcher reviewed multiple studies

  E: found capacity with chunking to be 4 +- 1 chunks

  L: therefore lower end of Millers estimate (5 digits) could be more appropriate than 9 digits