A psychologist investigated the effect of diet on concentration. Group 1 consumed a high-sugar energy drink at 8:00 AM and completed a concentration task. Group 2 consumed a sugar-free alternative at 4:00 PM and completed the same concentration task.
Identify one variable that might have been a confounding variable in this study. Justify your answer.
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.