In the study of context-dependent memory by Grant et al. (1998), how did the researchers control for the potential confounding effect of wearing headphones during the study and test phases?
All participants wore headphones during both phases, with the silent groups wearing headphones with no sound playing.
Only the participants in the noisy conditions wore headphones, while those in the silent conditions sat in a quiet room with no headphones.
Participants were allowed to choose whether to wear headphones, and their choice was used to match them into groups.
Headphones were worn by all participants during the study phase, but were completely removed by everyone during the test phase.
