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How many times does the chorus repeat
in your favorite song?

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And, take a moment to think,
how many times have you listened to it?

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Chances are you've heard that chorus
repeated dozens, if not hundreds, of times,

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and it's not just popular songs in the West
that repeat a lot.

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Repetition is a feature that music from
cultures around the world tends to share.

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So, why does music rely
so heavily on repetition?

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One part of the answer come from what
psychologists call the mere-exposure effect.

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In short, people tend to prefer things
they've been exposed to before.

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For example, a song comes on the radio
that we don't particularly like,

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but then we hear the song at
the grocery store, at the movie theater

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and again on the street corner.

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Soon, we are tapping to the beat,
singing the words,

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even downloading the track.

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This mere-exposure effect doesn't
just work for songs.

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It also works for everything 
from shapes to Super Bowl ads.

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So, what makes repetition so
uniquely prevalent in music?

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To investigate, psychologists asked
people to listen to musical compositions

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that avoided exact repetition.

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They heard excerpts from these pieces
in either their original form,

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or in a version that had been digitally
altered to include repetition.

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Although the original versions
had been composed by

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some of the most respected 
20th century composers,

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and the repetitive versions had been
assembled by brute force audio editing,

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people rated the repetitive versions
as more enjoyable, more interesting

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and more likely to have been
composed by a human artist.

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Musical repetition is deeply compelling.

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Think about the Muppets classic,
"Mahna Mahna."

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If you've heard it before,

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it's almost impossible after I sing,
"Mahna mahna,"

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not to respond, "Do doo do do do."

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Repetition connects each bit of music


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irresistibly to the next bit 
of music that follows it.

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So when you hear a few notes,
you're already imagining what's coming next.

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Your mind is unconsciously singing along,

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and without noticing,
you might start humming out loud.

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Recent studies have shown that when
people hear a segment of music repeated,

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they are more likely to move
or tap along to it.

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Repetition invites us into music
as imagined participants,

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rather than as passive listeners.

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Research has also shown

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that listeners shift their attention
across musical repetitions,

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focusing on different aspects of
the sound on each new listen.

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You might notice the melody
of a phrase the first time,

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but when it's repeated, your attention
shifts to how the guitarist bends a pitch.

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This also occurs in language,
with something called semantic satiation.

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Repeating a word like atlas ad nauseam

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can make you stop thinking about 
what the word means,

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and instead focus on the sounds:
the odd way the "L" follows the "T."

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In this way, repetition can 
open up new worlds of sound

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not accessible on first hearing.

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The "L" following the "T" might not be
aesthetically relevant to "atlas,"

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but the guitarist pitch bending
might be of critical expressive importance.

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The speech to song illusion
captures how simply

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repeating a sentence a number of times
shifts listeners attention

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to the pitch and temporal
aspects of the sound,

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so that the repeated spoken language

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actually begins to sound
like it is being sung.

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A similar effect happens with 
random sequences of sound.

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People will rate random sequences
they've heard on repeated loop

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as more musical than a random
sequence they've only heard once.

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Repetition gives rise to a kind of
orientation to sound

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that we think of as distinctively musical,
where we're listening along with the sound,

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engaging imaginatively with the note
about to happen.

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This mode of listening ties in with our
susceptibility to musical ear worms,

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where segments of music
burrow into our head,

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and play again and again,
as if stuck on repeat.

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Critics are often embarrassed
by music's repetitiveness,

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finding it childish or regressive,

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but repetition, far from an embarrassment,
is actually a key feature

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that gives rise to the kind of experience
we think about as musical.