Short term Memory research

• JACOBS (CAPACITY)

  • Procedure - Participants were presented with a series of letters or digits, which they had to repeat back to the experimenter in the same order they were presented (serial recall). The list increased by a single item until participants consistently made mistakes.
  • Findings – The average STM span was between 5-9 items. Digits (9.3) were recalled better than letters (7.3). STM span increased with age e.g. 8 year olds (6.6) and 19 year old (8.6)
• PETERSON x2 (DURATION)

  • Procedure – They presented nonsense trigrams (i.e. VGT, PXR) to participants, and asked them to recall the trigrams after either 3,6,9,12,15 or 18 seconds. They were prevented from rehearsing the trigrams by being asked to count backwards in 3’s from 999. The % of trigrams correctly recalled was recorded for each time interval.
  • Findings – Peterson and Peterson found that if rehearsal is prevented then recall is negatively affected with the maximum duration being around 18-30 seconds
• BADDELEY (CODING)

  • Procedure – Participants were presented with one of two word lists: List A; acoustically similar words and List B; acoustically dissimilar words. To test coding, participants were given the list in the wrong order. Their task was to rearrange the words in the correct order.
  • Findings – Participants given List A (acoustically similar) performed worse, with a recall of only 10%. They confused similar-sounding words, e.g. recalling ‘cap’ instead of ‘cat’, suggesting that STM is coded on an acoustic basis.