Duration Of The STM

Question 1

Peterson & Peterson (1959) investigated the duration of short-term memory by conducting a laboratory experiment with a sample of 24 psychology students.

The students had to recall meaningless three-letter trigrams (for example, THG, XWV) at different intervals (3, 6, 9, 12, 15 or 18 seconds). To prevent rehearsal (practice) the students had to count backwards in threes or fours from a specific number, until they were asked to recall the letters.

What were the findings?

Answer 1

The longer the interval the less accurate the recall

3 second interval = 80% of trigrams recalled correctly

18 second interval = 10% of trigrams recalled correctly

Question 2

After the study what did Peterson & Peterson (1959) conclude?

Answer 2

The STM has a limited duration of 18 seconds when there’s no maintenance rehearsal