M - Short- and long-term memory Flashcards
In what 3 ways are STM and LTM different?
In their capacity, duration and coding.
How can the capacity of STM be assessed?
Using digit span.
Who used the digit span test to measure the capacity of STM?
Joseph Jacobs (1887).
What were the findings of the digit span test by Joseph Jacobs in 1887?
The avg digit span was 9.3 items and 7.3 for letters.
What did Joseph Jacobs suggest was the reason for the avg span of digits being 2 higher than for letters?
There are only 9 numbers whereas there are 26 letters.
Who came up with the magic number 7 +/- 2?
George Miller (1956).
What did George Miller discover about the capacity of STM?
The span of immediate memory is about 7 items - sometimes a bit more, sometimes a bit less.
He noticed people can count 7 dots flashed onto a screen but not many more.
Same with recall of music notes, letters and words.
He also found that people can recall 5 words as well as they can recall 5 letters - we chunk things together and can remember them more.
Who studied the duration of STM?
LLoyd and Margaret Peterson (1959).
Describe how Peterson and Peterson studied the duration of STM.
- 24 students.
- Each ppt tested over 8 trials.
- On each trial a ppt was given a consonant syllable and a 3 digit number (e.g. THX 512).
- Asked to recall consonant syllable after a retention interval of 3, 6, 9, 12, 15 or 18 seconds.
- During retention interval they had to count backwards from their 3 digit number.
What were the findings of Peterson and Peterson’s study of the duration of STM?
Ppts on avg were:
90% correct over 3s
20% correct after 9s
2% correct after 18s
What did the findings of the Peterson’s study suggest about the duration of STM?
STM has a very short duration - less than 18s - as long as verbal rehearsal is prevented.
Who studied the duration of LTM?
Harry Bahrick et al. (1975).
Describe how Harry Bahrick et al. studied the duration of LTM.
- 400 people.
- Various ages (17-74).
- On memory of classmates.
- Photo recognition test consisted of 50 photos, somefrom ppts high school yearbook.
- In a free recall test ppts were asked to list the names they could remember of those in their graduating class.
What were the findings of Harry Bahrick et al’s. study of the duration of LTM?
Ppts who were tested within 15 years of graduation were about 90% accurate in identifying faces. After 48 years, 70% for photo recognition.
Free recall was about 60% accurate after 15 years. 30% after 48 years.
Define capacity
A measure of how much can be held in memory. It is represented in terms of bits of information such as number of digits.
