STM, LTM and Duration Flashcards
What is duration?
A measure of how long a memory lasts before it is no longer available.
What is Short-term memory (STM)?
Your memory for immediate events. The short-term memory store has limited duration and capacity.
What is Long-term memory (LTM)?
Your memory for events that have happened in the past. The long-term memory store has potentially unlimited duration and capacity.
What did Shepard’s study do and find?
Shepard (1967) tested duration of LTM. He did this by showing participants 612 memorable pictures one at a time. An hour later they were shown some more pictures, some of which were repeated, they showed almost perfect recognition. Four months later they still recognised 50% of the photographs.
This shows that LTM has a very long duration.
What did Bahlrick et al’s study do and find?
Bahlrick et al (1975) showed people of various ages their high-school yearbook at asked them to put names to faces. 48 years on, people still had a 70% accuracy.
This shows both the great duration of LTM but also that we remember things better when they have meaning to us.
What did Peterson and Peterson do and find?
Peterson and Peterson (1959) had 24 students hear a meaningless trigram followed by three numbers. They were then asked to count backwards in 3s or 4s from a random number.This was called the retention interval and was to prevent rehearsal . They were then asked to recall the trigram. Participants were given 2 practice trials followed by 8 real trials, each with different items and the retention time varying.
They found 90% accurate recall with a 3 second interval and a 2% accurate recall with a 18 second interval. Indicating that without rehearsal STM lasts 20 seconds maximum.
What studies challenge with Peterson and Peterson?
Marsh et al (1997) found that when recall is unexpected it lasts 2 seconds. Indicating that expectation effects recall.
Nairne et al (1999) found that when the same items are used across trials recall increases up to 96 seconds. Indicating that STM lasts longer if nothing replaces it.
