Duration of STM - Peterson and Peterson (1959)

Question 1

Aim

Answer 1

To examine how long info can remain in the STM.

Question 2

Procedure

Answer 2

• Lab experiment.
• Sample of 24 psychology students selected.
• Given a random 3-letter consonant syllable trigram, eg, (CZD) and then a 3-digit number.
• Participants were asked to count backwards from the 3 digit number (interference task to avoid repetition of the trigram).
• They were asked to stop after differing amounts of time, eg, 3,6,9,12,15 or 18 seconds.

Question 3

Findings

Answer 3

80% recalled accurately after 3 seconds
10% recalled accurately after 18 seconds

Question 4

Conclusion

Answer 4

STM has a limited duration of approximately 18-30 seconds.

Question 5

Strength

Answer 5

• Lab experiment so there was a standardised procedure and a high level of control over the variables.
• Extraneous variables were minimised.
• Easily replicable.
• High reliability.

Question 6

Weakness

Answer 6

• Has sample bias.
• 24 psychology students participated meaning that findings were possibly unrepresentative and therefore cannot be generalised to the wider population.

Question 7

Weakness

Answer 7

• Artificial stimuli involved.
• Recalling a 3-letter consonant syllable trigram is arguably not representative of everyday tasks.
• Lacks ecological validity.