Arousal and mood factors in the "Mozart effect".

Some investigators of the "Mozart effect" have not controlled for the influence of differences in arousal or mood induced by treatment conditions. Studies by Rideout and colleagues reported differences in spatial reasoning after listening to a Mozart sonata compared against a relaxation instruction tape. The conditions may have affected subjects' arousal differentially, with the sonata increasing arousal and the relaxation instructions decreasing arousal, which could have affected spatial reasoning performance. Evidence is cited in support of this suggestion and indicates the importance of analyzing the influence of arousal differences in Mozart effect research.