Average recall performance (and standard errors of the mean) for the 7 recall stages (r1-r7) broken down for the three groups (control, vocal, and instrumental music). Recall 5 (r5) and recall 6 (r6) were conducted 10 and 30 minutes after recall 4 (r4). Recall 7 (r7) was conducted 2 weeks after the experiment. The participants of the vocal and instrumental groups received background music stimulation during the learning sessions r1-r4. The recall scores presented here are adjusted for psychometric intelligence.