In a study investigating the effect of binaural auditory stimulation on working memory, 40 university students were recruited. One group of 20 participants listened to 15 Hz beta-frequency binaural beats through headphones for 10 minutes before completing a complex backward digit-span task. The other group of 20 participants sat in silence for 10 minutes before completing the identical task. The performance was measured by the length of the longest sequence correctly recalled.
The researcher used an independent groups design, meaning different participants were assigned to each of the two conditions. The researcher is concerned that individual differences in baseline cognitive capacity or natural memory ability may have compromised the internal validity of the findings.
Explain one way in which the experiment could be changed to control for the problem of using different participants in each condition.
689 exam-style questions on AQA A Level Psychology Scientific processes. Each one has a worked solution and a mark scheme showing where the marks go.