Short term memory

• Capacity experiment- Jacobs (1887)


  To determine how much information can be held at one time in STM
• Capacity experiment Jacobs (1887)

  1. A row of numbers on each slide
  2. Recall as many as you can in the right order immediately
• Capacity experiment Results


  Mean digit span: 9.3 digits

  Mean letter span: 7.3 letters

  Concluded STM can hold 7±2 items
• Chunking- Miller


  Thought we were able to remember 7±2 'chunks' (represents more information) at a time not item
• Duration experiment - Peterson and Peterson (1959)

  1. Gave participants triagrams with 3 constants
• Duration experiment- Condition 1


  Show participants for 2 seconds and recall immediately
• Duration experiment - Condition 2


  Show participants for 2 seconds, count backwards from 100 for 3 seconds
• Duration experiment- Condition 3


  Different triagram, 6 second delay (counting back) and then recall
• Duration experiment- Condition 4


  Different triagram, 15 second delay
• Duration experiment- Condition 5


  Different triagram, 15 second delay
• Duration experiment- Condition 6


  Different triagram, 18 second delay
• STM conclusions

  • Mainly acoustic coding
  • 18-30 second duration
  • Duration can be extended by maintenance rehearsal
• Maintenance rehearsal


  Repeating information without thinking about the meaning or connecting it to other information