Studies into coding, capacity and duration in STM & LTM

what did baddeley (1966) study?

Coding in STM and LTM

What did Baddeley find?

• gave different word lists to four groups of ppts to rmb

List A: acoustically similar

List B: acoustically dissimilar

List C: semantically similar

List D: semantically dissimilar

• immediately after were given list containing og words in wrong order

• they had a task to to rearrange words into correct order, recall from STM

what did miller study?

Capacity of STM

what did miller (1956) find?

• ppts were presented with a increasingly long sequence of digits

• they had to recall in order

• when recall fell below 50% miller took this as their digit span capacity

• ppl had recalled 5-9 pieces of info and called it the magic number 7 (+/-2)

• chunking increases capacity of STM

What did Peterson and Peterson study?

Duration of STM (without rehearsal)

What did Peterson and Peterson find?

• ppts asked to read nonsense trigrams and count back immediately after in threes for between 3-18 seconds to prevent rehearsal

• they then had to recall trigrams in order

• they found after 3secs retention interval ppts recall was 3%

• duration of STM is up to 18secs without rehearsal

What did Bahrick et al (1975) study?

Duration of LTM

What did Bahrick et al (1975) find?

• 400 ppts between 17-74 years of age

• some given free recall test and asked to rmb old classmates names

• others were given photo-recognition test, photos after we a cue to help LTM recall

• FOUND: those given photo-recogn task + who had left school in the previous 15 yrs recalled 90 faces & names, this dropped to 80% names, 70% faces for those who had left in the last 48 years

• Those given free recall test rmb less than those given photo recog test

• findings suggest LTM may last up to a lifetime but can decline a little overtime and that cues improve our recall from LTM