Short term memory

• Coding

  • raw info from the SR is encoded into a form that the STM can deal with more easily
  • prefers acoustic coding

  Baddeley

  • 75Ps presented lists of 10 short words that were repeated four times
  • some were acoustically similar
  • Ps given a list containing the original words in the wrong order and their task was to rearrange the words into the correct order
  • 10% recall for acoustically similar compared to 60-80% for other lists
  • BUT this only researches acoustic encoding
• Duration

  • limited- up to about 30 seconds

  Peterson and Peterson

  • presented 24 undergraduate students with consonant trigrams
  • during the time before recall, Ps had to count backwards in 3s to prevent rehearsal
  • after 3 seconds the recall rate was 90% and after 18 seconds only 5%
  • there is little research into the duration of other forms, such as visual
• Capacity


  • limited to about 5-9 items

  Jacobs (1887)

  • digit span method- Ps presented with increasingly long lists of numbers or letters that had to be recalled in order
  • numbers - 9 items recalled
  • letters - 7 items recalled

  Miller (1956)

  • built on Jacobs' research
  • found that the "chunk" was the basic unit of STM
  • 5-9 chunks can be held in STM at any one time
• A03 for these studies

  -all use lab experiments and can be criticised for a lack of mundane realism due to the way that they tested memory
• Reasons for forgetting in STM


  • capacity + displacement theory
  • suggests that sometimes new information pushes out old information due to the limited number of slots in the memory
  • duration
  • linked to trace decay
  • the idea that information will fade away over time
  • it is hard to fully operationalise trace decay in research as new information will always enter the mind in between learning and recall so forgetting in STM can also be explained by interference