Short and Long Term Memory

CAPACITY

• Capacity determins how much data can be held in a memeory store. STM is a limitted capacity store whereas LTM has a potentilaly infinite capacity.
• STM: Jacob digit span technique showed that the avergae soan for digits was 9.3 items, and 7.3 items for letters. This is because there are only nine numbers, but 26 letters.
•  Immediate memory: Miller magic number seven plus or minus two. The span for immediate memory is 7 items - sometimes more, sometimes less. People count count 7 dots when flashed onto a screen, and the same goes for musical notes, letters and even words. People can recall five words, as well as five letters as we chunk things together to remember them more.

Evaluation and Discusssion

• Cowan reviewed studies - STM capacity is limited to four chunks. Vogal found that for visual info four items was the limit. Thus, the lower end of Miller's range is appropriate. This suggests that STM is not as extensive as once thought.
• Size of the chunk also matters. Simon - people had a shorter memory span for larger chunks like eight letter words as opposed to smaller chunks like one-syllable words. This continues to support the view that STM has a limtted capacity.
•  Individual differences. Jacobs found that recall/digit span increased with age. Those 8 years old = 6.6 digits, yet those 19 years old  = 8.6 digits. This could be due to increased capacity or because people develop strategies to remember things better like chunking. This suggests that the capacity of STM is not fixed and individual differences may play a vital role.

DURATION

• LTM potentially lasts forever but STM doesnt last long - it has a short duration…