In search of concentration, and the Zeigarnik Effect

I heard about the Zeigarnik Effect for the first time today, from an article about earworms.

"In psychology, the Zeigarnik effect states that people remember uncompleted or interrupted tasks better than completed tasks....The Zeigarnik effect suggests that students who suspend their study, during which they do unrelated activities (such as studying unrelated subjects or playing games), will remember material better than students who complete study sessions without a break." (from Wikipedi...