Capacity

• Psychologists are also interested in how much information can be stored in our memory. Long term memory is believed to have an unlimited capacity. However, research into the STM has shown a much smaller capacity.
• Miller (1956) concluded that the capacity of the STM is about 7+/-2 items. However, he believed it was possible to increase the capacity of our STM through chunking. For example, a pin number has only 4 digits so this falls within the capacity of the STM. However, mobile phone numbers are 11 digits which exceeds the maximum capacity of 9 items. Therefore, if we chunk a mobile number into smaller chunks, it is possible to store this in the STM
• Strength - Jacobs (1887) study. used the serial digit span technique to measure the capacity of STM. Gave participants one letter/number to recall. If they get that right they are given two to recall, if recall is accurate they are given three to recall, and so on. The study stops when they make a mistake. The digit span is the number of letters or numbers in the final set correctly recalled. = average ds numbers - 9.3 letters - 7.3 . Letters are assumed to be harder to remember as there are more of them so more opportunities to go wrong. supports the idea that the STM can hold 7+/-2 items.
• However, a limitation of this research into the capacity of the STM is that it fails to take individual differences into account. For example, there is strong evidence to suggest that memory declines with age. Jacob's (1887) research used participants who were between 8-19 years of age. This suggests that the capacity of the STM may be different for those who are older than this. This is a limitation because the findings may not be generalisable to all.