short term long term

• • definition of Capacity

  capacity is a measure of the amount of information the memory can hold (measured in chunks)
• • research into capacity included
  • Miller’s reviewed studies into the capacity of STM found that short term memory is 7+-2.
  • Jacobs used a technique called the digit span technique 
  • participant were given a number of digits has to immediately recall a sequence of letters or numbers which increased by one letter or number with each trial. The mean amount of letters that could be correctly recalled was 7.3 and number 9.3
  • LTM capacity could be limitless
• evaluation of capacity

  One criticism is that other researchers have found that the capacity of the short term memory could be more limited. Cowan did a meta analysis of studies and found that the capacity could be more like 4 chunks. These results were replicated in a subsequent study about remembering visual info where they also found 4 as the limit therefore miller's lower end of 5 may be incorrect reducing the validity of his findings (should reconsider)
• Another criticism into capacity is that there may be individual differences. For example jacobs found that capacity of the long term memory can increase steadily with age he found that 8 years olds could remember 6.6 chunks whereas 19 yr olds could remember 8.8 therefore showing that differences in age could cause the change in capacity and it could vary more than miller’s 7+-2

  might be evidence to say that the STM's capacity increases over-time.
• duration defintion

  The length of time information stays in the brain before it becomes no longer available 
• research into duration

  • Peterson and Peterson studied the duration of short term memory by showing participants 3 meaningless consonants which they had to recall at the end of counting down from a time interval (ensuring they weren't actively recalling) the longest interval being 18 seconds- which is the max duration STM
  • Bharick- LTM. He conducted a study where he asked people to recall through photo recognition names of their classmates after graduation, after 45 years levels of recognition were still at 70%,
  • duration of long term memory could potentially be limitless.
• evaluation of duration

  One limitation of research into duration is that it lacks ecological validity. It is very rarely that in our everyday life we will be asked to recall something like pointless consonants such as in the epterson and peterson study and therefore these wont be generalisable to real life, however there are some exceptions such as phone numbers where we have to remember meaningless numbers,even though it is artificial it may
• Encoding definition

  • Coding is the way in which information is changed for it to be remembered (entering into brain through the sense and taking on various forms)
• reserach into coding

  • Baddeley found that information in the short term memory is encoded acoustically and long term memory semantically.
  • more mistakes are made when recalling acoustically-similar words straight after learning them, whilst more mistakes are made when recalling semantically-similar words 20 minutes after learning them (LTM recall)
• A criticism of coding is that there is research to suggest that information may not be encoded exclusively semantically and acoustically Some experiments have also shown visula codes being present and used in the stm, brandimote found this was the case when there were given a visual task.. Frost also showed long ter recall can be visual showing memory may not b exclusively encoded sematically or acoustyically and can vary due to circumstances and the task .
• • Many studies such as these use artificial and meaningless stimuli (for example, Baddeley's into conding used simply word lists). This is a weakness because they do not reflect how memory works in everyday life, so they lack external validity.