A cognitive psychologist conducted a lab experiment to investigate the effects of room temperature on memory recall. Participants in Group A recalled a list of 20 words in a hot room (28∘C28^\circ\text{C}28∘C), while participants in Group B recalled the same list in a cool room (18∘C18^\circ\text{C}18∘C). The psychologist used random allocation to assign participants to the groups.
Apart from using random allocation, suggest one way in which the psychologist might have improved this study by controlling for the effects of extraneous variables. 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.