Peterson and Peterson (1959) The Duration of the STM

Question 1

Method

Answer 1

• Participants shown nonsense trigram (3 random consonants, e.g. CVM) and asked to recall them after either 3, 6, 9, 12, 15, or 18 seconds,
• During the pause, they were asked to count backwards in three from a given number; an interference task to prevent them from repeating the letters internally.

Question 2

Results

Answer 2

• After 3 seconds, participants could recall 80% of trigrams correctly,
• After 18 seconds, only about 10% were recalled correctly.

Question 3

Conclusion

Answer 3

• When rehearsal is prevented, very little can stay in STM for longer than about 18 seconds.

Question 4

Evaluation

Answer 4

• Results are likely to be reliable; laboratory experiment; variables tightly controlled,
• Nonsense trigrams are artificial; study lacks ecological validity,
• Meaningful/ real-life memories may last longer in STM,
• Only one type of stimulus used; duration of STM depends on the type of stimulus,
• Each participant saw multiple different trigrams, could have led to confusion, meaning that only the very first trigram was a realistic trial.