Why Does a Tune Keep Looping in the Mind?

After leaving a shop, a chorus heard for only a few seconds may keep replaying in the mind. Researchers call this music that appears without deliberate recall involuntary musical imagery, commonly known as an earworm. It is usually a short, familiar piece of melody or lyrics, and it is not the same as hearing a sound coming from the outside world.

There is no single cause that applies to everyone. Studies have recorded triggers including recent exposure to a song, a related word or place, emotion and personal memory, as well as moments with a low attentional load. A shop chorus may first be activated by recent exposure. Later, while doing repetitive chores, the external task demands less attention and internal auditory imagery can become more noticeable. Certain melodic features and song popularity are associated with occurrence, but these are statistical relationships; a song's structure cannot precisely predict when one person will get stuck with it.

The loop also need not be explained as the brain being forced to finish an 'incomplete song'. A comprehensive 2020 review describes involuntary musical imagery as involving musical memory, auditory imagery, attention and individual differences, with evidence still supporting several pathways. Experience sampling also shows that retrospective questionnaires may miss some circumstances.

Most earworms are brief and neutral or pleasant. Some people find them distracting, while others enjoy them. An ordinary repeating tune cannot diagnose obsessive-compulsive disorder or another condition. Frequency and impact should be distinguished: an occasional episode shows that musical memory can be cued without a deliberate command. Only when the experience causes persistent distress or significantly disrupts daily life does it become a more specific problem to assess.

https://pmc.ncbi.nlm.nih.gov/articles/PMC7704448/
https://pmc.ncbi.nlm.nih.gov/articles/PMC3908735/
https://www.sciencedirect.com/science/article/abs/pii/S1053810015000410