AO3

• Peterson & Peterson used a sample of 24 psychology students, which is an issue for two reasons.
• Firstly, the psychology students may have encountered the MSM of memory previously and therefore may have demonstrated demand characteristics by changing their behaviour to assist the experimenter.
• Secondly, the memory of psychology students may be different from that of other people, especially if they had previously studied strategies for memory improvement. As a result we are unable to generalise the results of this study to non-psychology students.
• Furthermore, it could be argued that Peterson & Peterson's study has low levels of ecological validity. In this study participants were asked to recall three-letter trigrams, which is unlike anything people would want to memorise in their everyday lives. As a result we are unable to apply these results to everyday examples of memory and are unable to conclude if the duration of STM may be longer for more important information, such as a vital phone number.
• ⚫ However, Peterson & Peterson's study was highly controlled and took place in a laboratory of Indiana University. As a result Peterson & Peterson had a high degree of control for extraneous variables, which makes their procedure easy to replicate to test reliability.