Duration

• STM


  Peterson and Peterson

  A: wanted to study the duration information can be held for in the STM

  P: 24 university students

  presented with a nonsense trigram followed by a 3 digit number

  afterwards ppts had to count backwards from the number they were presented in 3s or 4s

  F: at a 3 second interval ppts remembered about 90% of the trigrams

  at an 18 second interval ppts only remembered 2%

  C: information disappears very rapidly in the STM when rehearsal is prevented -> around 18-30s
• STM Strength - replicable

  used a highly standardised procedure with high control over all variables.

  trigrams being nonsense consonants and therefore task being the same for all.

  makes it easier to repeat the study with same procedure and assess the reliability of results
• STM Weakness - lack of ecological validity

  conducted in a highly controlled, artificial setting

  task ppts did lack mundane realism as this isn't typically how STM would be used in day to day life

  difficult to generalise the findings outside of the study
• STM Weakness - lack of population validity

  study was conducted using 24 university students ppts, who may not be representative of the wider population

  sample size is small

  university students' STM duration is different to most -> have to utilise their memory more often for their studies + exams
• LTM


  Bahrick et al

  A: investigate the duration of LTM

  P: asked 392 graduates of various ages from age 17-74

  asked to recall their memory of former classmates

  used various memory tests including recognition of classmates, pictures matching names to pictures

  F: ppts performed well up to about 34yrs although performance was better on recognition tasks than on recall tasks.

  dip in performance after 47yrs

  C: duration of the LTM can potentially last a lifetime
• LTM Strength - high ecological validity

  recognitions/recall of names/faces is a way in which we use out memory in everyday life

  has mundane realism and suggests the findings can be generalised outside of the study
• LTM Weakness - extraneous variables

  some ppts may have been in contact with some of their ex-classmates therefore means the duration of memory being tested wasn't accurate

  lowers validity + reliability of the findings