CAPACITY

• what is capacity?

  the amount of information that can be stored at once
• What is the capacity of short term memory?

  7 +/- 2 chunks of information
• what is the capacity of LTM?

  Potentially unlimited
• How did Jacobs investigate capacity?

  Digit Span

  The researcher read 4 digits and increases each time until the participant cannot recall the order correctly.

  The final number = digit span
• What were Jacobs findings?

  on average participants could repeat back 9.3 numbers and 7.3 letters
• How did miller investigate capacity?

  Magic Number 7+/- 2

  observed everyday practice, noted that things come in sevens (days of the week, deadly sins ect
• What were Miller's findings?

  the span of STM is about 7 items (Plus or minus 2) but it is increased by chunking
• what is chunking?

  grouping sets of digits/letters into meaningful units
• Strength

  Jacobs study has been replicated - the old study might have lacked controls but his findings have been confirmed over 100 years later in controlled studies
• limitation

  miller may overestimate stm capacity

  other research was reviewed and concluded that it was only 4 plus or minus 1, suggests lower end of estimate is more appropriate