A sports science researcher wants to investigate the effect of background music on athletic endurance. Participants are asked to run on a treadmill to exhaustion while listening to either 'high-motivation' or 'low-motivation' music.
The researcher selected the music tracks himself, classifying them as 'high-motivation' or 'low-motivation' entirely based on his own personal opinion.
Explain how this study's methodology could be improved to increase the validity of this independent variable.
Practise AQA A Level Psychology Scientific processes with exam-style questions for A Level Psychology. 100 questions, matched to the AQA A Level Psychology (7182) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.