Have you gotten stuck with a song replaying itself over and over in your head? A Russian psychologist, Bluma Zeigarnik (1900-1988) reportedly first described what is now known as the Zeigarnik Effect in her doctoral thesis in 2917, which may help to explain that. It is a tendency for the brain to remember uncompleted or interrupted tasks better than those that have been completed. In a similar way, you may have found yourself thinking again and again about some task that is only partly done and you know you need to finish it. Back to the song replaying endlessly inside your head. What can you do? If you know the song well enough, repeat or sing or hum the last verse or the last chorus and immediately choose to think about something else. This sends a signal to your brain that the song (the task) is finished and it is time to move on to something else. There have been times I had to repeat this action two or three times but it usually works—my brain moves on to something else.