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 had to immediately recall a sequence of digits which increased by one 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 questionthe validity of his findings (should reconsider)

  • limitations of a meta-analysis
• Another criticism into capacity is that there may be individual differences. For example jacobs found that capacity of the STM 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

  • 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
  • material given to pps artificial
  • wont be generalisable to hpow memory performs real life,
  • exceptions such as phone numbers where we have to remember meaningless numbers
  • sample of 24 psychology students- only in one indiana uni=biased and small smaple size
• 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)
  • shows it relies on acoustuic
• 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.
• G: generalisation eg age, gender, culture etc.R: reliability-is it repeatable? was it repeated?A: application-does it provide evidence? in life?V: validity-any external distractions? representative?E: ethics- was this consensual? how did researchers address this?M: mundane realism- is this applicable to everyday life? artificial task? how was this studied.
• strengths of bharick

  • Every day meaningful memories ( e.g of peoples faces and names) were studied.
  • When the lab studies were done with meaningless pictures to be remembered, recall rates were lower (e.g. Shepard 1967)
  • This means that Bahrick et al's findings reflect a more 'real' estimate of the duration of LMT
  • Researchers couldn't control whether participants had seen or been in contact with classmates before the test, potentially affecting their memory
  • potential they rehearsed the names of their classmates more than others, which could have influenced their recall.
• evaluation for capacity- ecological validity however because he used reviewed ultiple studies it has a larger sample size and can have populational valiidty