Duration of STM - Peterson and Peterson (1959)

Question 1

Aim

Answer 1

To investigate the duration of short-term memory (STM).

Question 2

Procedure

Answer 2

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

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

• Laboratory experiment therefore key variables were manipulated or controlled.
• Extraneous variables were minimised.
• This increases the reliability of this study and therefore its replicability.

Question 6

Weakness

Answer 6

• 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 nonsense 3-letter consonant syllable trigram is arguably not representative of everyday tasks.
• Lacks mundane realism.

Question 8

Weakness

Answer 8

• The requirement to count backwards may have displaced the trigrams rather than just preventing rehearsal, meaning the study may not have measured pure decay but rather interference.
• Lacks internal validity.