PETERSON & PETERSON~ tested duration, showed ppts trigrams asking them to recall them every 3,6,9,12,15,18 secs; during pause they had to count backwards in 3's (interference task which prevents the repetition of the trigram by the ppt), after 3 secs- 80% correct recollection, after 18 secs- 10% correct recollection, longer the interval = less accurate the recall
STRENGTH- lab (reliable)
LIM- artificial task so lacks ecological validity
CONCLUSION~ STM has limited duration of approx 18 sec. If we're unable to rehearse information it will not be passed to LTM, providing further support for the MSM and the idea of seperate components