Representation of the study intervention. Participants (n = 96) were split into quiz and study-quiz groups by simple randomization. During s0 both groups performed the quiz task during 15 minutes. On s1 and s2 the quiz group performed the quiz task again for 15 minutes. The study-quiz group performed a 20 minute study task, immediately followed by the 15 minute quiz task. Sessions were separated by one week intervals.