capacity

• Capacity is the amount of information each store can hold
• capacity was measured by Jacob Josephs in 1887, using he digit span test
• an individuals digit span is the maximum number digits they can recall in the correct order that they have learned them
• Jacobs found the mean span for digits was 9.3 items, but mean span for letters was only 7.3
• span of memory and chunking was investigated by George Miller in 1956, by making observations of everyday practice
• George miller noted a lot of things come in 7s, such as notes on a musical scale, days of the week, colors in the rainbow etc.
• due to his observations, miller thought the average capacity of STM was 7 +/- 2 items
• Miler also noticed that 5 words are recalled just as easily as 5 letters, so called this 'chunking', where each item can be one 'chunk'
• +Jacob's study has high validity and can be easily replicated. Newer studies find same results, high reliability
• -miller may have overestimated STM. Nelson Cowen suggested capacity was only 4 +/-1. Suggests low reliability
• Researched by Joseph Jacob's and George Miller