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The words to a holiday song bubble up to the surface of the brain, even decades since last hearing the tune. Yet recalling a bank-account password can put the mind in a twist. Neuroscientists have long debated the brain mechanisms related to memory, but they agree on one thing: Information set to music is among the easiest to remember. One expert, Henry L. Roediger III, professor of psychology at the Memory Lab at Washington University in St. Louis, explains how songs easily stick in the mind.

—Heidi Mitchell

The Brain’s Data Processors

The hippocampus and the frontal cortex are two areas in the brain associated with memory and they process millions of pieces of information every day. Getting the information into those areas is relatively easy, says Dr. Roediger. What is difficult is pulling data out efficiently. Music, he says, provides a rhythm, a rhyme and often, alliteration. All that structure is the key to unlocking information stored in the brain—with music acting as a cue, he says.

If someone “asks me to produce all the words to a Beatles song, I couldn’t do it unless I sang it in my mind,” says the professor, who specializes in the study of memory retrieval.

Music is a powerful mnemonic device, but the song’s structure is what allows a person to recall the information it holds—not necessarily the catchy tune itself. The added melody encourages repetition and thus memorization, which is perhaps why patients with advanced Alzheimer’s dementia have been known to sing along to a familiar song.

Poetry of Memory

Some researchers think the brain function that responds to music evolved long before those related to language, says Dr. Roediger. Most neuroscientists believe humans developed music and dance to aid in retrieval of information.

He cites Duke University professor David C. Rubin’s work on epic poetry in preliterate and literate societies. Dr. Rubin’s studies show long stories—such as “The Iliad” and “The Odyssey”—were passed down verbally using poetic devices for a reason.

“Psychologists believe laws, stories and customs were presented as poems, chants and, eventually, as songs, in order for them to be memorized, and recalled, accurately,” says Dr. Roediger. “The idea was that the chant would help people to remember large sets of information across the ages.”

Rhyme With a Reason

People with exceptional abilities to recount lists and other data often create song-like structures to help with memorization and recall. Dr. Roediger, whose forthcoming book, “Make It Stick: The Science of Successful Learning,” offers tools for memorization, points to how nearly every American learns the Alphabet Song. He points to a study in which hospital workers in England could recite the institution’s asthma guidelines after a frustrated doctor set the rules to song and they went viral on YouTube.

Dr. Roediger remembers large sequences of information by using a common number-rhyming mnemonic that goes, “one is a gun, two is a shoe, three is a tree, etc.” He puts an image of whatever he needs to remember along with an image of the word associated with the number in the rhyme. “So if one is a ball, I’ll picture a gun shooting a ball. If two is a chair, I’ll imagine a shoe sitting on a chair, and so on.”

Adds Dr. Roediger, “The rhyme serves a similar function as a tune.”

—Email burning@wsj.com