Features of STM and LTM Flashcards
What is short term memory?
Your memory for events in the present or immediate past
What is long term memory?
Your memory of events that have happened in the more distant past
What is capacity?
How much data each memory store can hold
Which study measured capacity?
Jacobs (1887)
What was these procedure of the capacity study?
- Both digits and letters were tested
- Jacob’s would read out a list of items and ask the participant to repeat the list back to him in the correct order
- If successful, the participant would move on to the next list and an item was added each time
- This would repeat until the participant could no longer recall items in the correct order
What were the findings of the capacity study?
- 9.3 recalled for digits
- 7.3 recalled for letters
What article did George Miller (1956) write about memory?
- The magic number 7 plus or minus 2
- He concluded that the span of STM was 7 items, sometimes more (+2) sometimes less (-2)
- He also found that people could chunks items together to increase their capacity
What is the capacity of LTM?
Thought to be unlimited
What is duration?
How long each memory store can hold items
What was the study that measured duration of STM?
Peterson and Peterson (1959)
Explain the procedure of the STM duration study.
- 24 participants were tested over 8 trials
- One each trial, the participant was asked to recall a consonant syllable and a 3 digit number (e.g TWG 619)
- They were asked to recall the consonant syllable after a 3,6,9,12,15 and 18 second retention interval
- They were asked to count down from their 3 digit number to prevent them rehearsing their syllable
What were the findings of the STM duration study?
- Participants were 90% correct over 3 seconds, 20% correct after 5 seconds and only 2% correct after 18 seconds
- This suggests that STM has a very short duration when verbal rehearsal is prevented
What was the study done for duration of LTM?
Bahrick et al. (1975)
Explain the procedure of the LTM duration study.
- 400 people between the ages of 17-74
- A photo recognition test required the participants to select people that they had been to school with from 50 photographs (only some photos were the true classmates)
- In a free-recall test, participants were asked to list the names of those in their graduating class
What were the findings of the LTM duration study?
- Photo recognition test: participants tested after 15yrs of graduation were 90% accurate, declined to 70% after 48yrs
- Free recall test: 60% accurate after 15yrs, 30% after 48 yrs
- This suggests that we can form very long term memories but recall is improved when cues are present as they can retrieve the information
