WEBVTT 00:00:07.366 --> 00:00:11.939 How many times does the chorus repeat in your favorite song? 00:00:11.939 --> 00:00:16.572 And, take a moment to think, how many times have you listened to it? 00:00:16.572 --> 00:00:21.519 Chances are you've heard that chorus repeated dozens, if not hundreds, of times, 00:00:21.519 --> 00:00:25.239 and it's not just popular songs in the West that repeat a lot. 00:00:25.239 --> 00:00:30.792 Repetition is a feature that music from cultures around the world tends to share. 00:00:30.792 --> 00:00:34.455 So, why does music rely so heavily on repetition? 00:00:34.455 --> 00:00:39.937 One part of the answer come from what psychologists call the mere-exposure effect. 00:00:39.937 --> 00:00:44.084 In short, people tend to prefer things they've been exposed to before. 00:00:44.084 --> 00:00:48.135 For example, a song comes on the radio that we don't particularly like, 00:00:48.135 --> 00:00:51.421 but then we hear the song at the grocery store, at the movie theater 00:00:51.421 --> 00:00:53.606 and again on the street corner. 00:00:53.606 --> 00:00:56.311 Soon, we are tapping to the beat, singing the words, 00:00:56.311 --> 00:00:58.555 even downloading the track. 00:00:58.555 --> 00:01:02.135 This mere-exposure effect doesn't just work for songs. 00:01:02.135 --> 00:01:06.164 It also works for everything from shapes to Super Bowl ads. 00:01:06.164 --> 00:01:10.016 So, what makes repetition so uniquely prevalent in music? 00:01:10.016 --> 00:01:14.505 To investigate, psychologists asked people to listen to musical compositions 00:01:14.505 --> 00:01:16.960 that avoided exact repetition. 00:01:16.960 --> 00:01:20.281 They heard excerpts from these pieces in either their original form, 00:01:20.281 --> 00:01:24.623 or in a version that had been digitally altered to include repetition. 00:01:24.623 --> 00:01:26.675 Although the original versions had been composed by 00:01:26.675 --> 00:01:29.726 some of the most respected 20th century composers, 00:01:29.726 --> 00:01:33.984 and the repetitive versions had been assembled by brute force audio editing, 00:01:33.984 --> 00:01:38.647 people rated the repetitive versions as more enjoyable, more interesting 00:01:38.647 --> 00:01:43.250 and more likely to have been composed by a human artist. 00:01:43.250 --> 00:01:45.718 Musical repetition is deeply compelling. 00:01:45.718 --> 00:01:48.894 Think about the Muppets classic, "Mahna Mahna." 00:01:48.894 --> 00:01:49.979 If you've heard it before, 00:01:49.979 --> 00:01:53.181 it's almost impossible after I sing, "Mahna mahna," 00:01:53.181 --> 00:01:56.547 not to respond, "Do doo do do do." 00:01:56.547 --> 00:01:58.451 Repetition connects each bit of music 00:01:58.451 --> 00:02:02.092 irresistibly to the next bit of music that follows it. 00:02:02.092 --> 00:02:06.122 So when you hear a few notes, you're already imagining what's coming next. 00:02:06.122 --> 00:02:08.366 Your mind is unconsciously singing along, 00:02:08.366 --> 00:02:11.609 and without noticing, you might start humming out loud. 00:02:11.609 --> 00:02:15.383 Recent studies have shown that when people hear a segment of music repeated, 00:02:15.383 --> 00:02:18.287 they are more likely to move or tap along to it. 00:02:18.287 --> 00:02:22.630 Repetition invites us into music as imagined participants, 00:02:22.630 --> 00:02:25.081 rather than as passive listeners. 00:02:25.081 --> 00:02:26.622 Research has also shown 00:02:26.622 --> 00:02:30.410 that listeners shift their attention across musical repetitions, 00:02:30.410 --> 00:02:34.136 focusing on different aspects of the sound on each new listen. 00:02:34.136 --> 00:02:36.970 You might notice the melody of a phrase the first time, 00:02:36.970 --> 00:02:41.971 but when it's repeated, your attention shifts to how the guitarist bends a pitch. 00:02:41.971 --> 00:02:46.183 This also occurs in language, with something called semantic satiation. 00:02:46.183 --> 00:02:48.984 Repeating a word like atlas ad nauseam 00:02:48.984 --> 00:02:52.002 can make you stop thinking about what the word means, 00:02:52.002 --> 00:02:57.073 and instead focus on the sounds: the odd way the "L" follows the "T." 00:02:57.073 --> 00:03:00.086 In this way, repetition can open up new worlds of sound 00:03:00.086 --> 00:03:02.853 not accessible on first hearing. 00:03:02.853 --> 00:03:07.203 The "L" following the "T" might not be aesthetically relevant to "atlas," 00:03:07.203 --> 00:03:11.492 but the guitarist pitch bending might be of critical expressive importance. 00:03:11.492 --> 00:03:13.960 The speech to song illusion captures how simply 00:03:13.960 --> 00:03:17.639 repeating a sentence a number of times shifts listeners attention 00:03:17.639 --> 00:03:20.690 to the pitch and temporal aspects of the sound, 00:03:20.690 --> 00:03:22.371 so that the repeated spoken language 00:03:22.371 --> 00:03:26.144 actually begins to sound like it is being sung. 00:03:26.144 --> 00:03:29.185 A similar effect happens with random sequences of sound. 00:03:29.185 --> 00:03:33.430 People will rate random sequences they've heard on repeated loop 00:03:33.430 --> 00:03:37.624 as more musical than a random sequence they've only heard once. 00:03:37.624 --> 00:03:41.181 Repetition gives rise to a kind of orientation to sound 00:03:41.181 --> 00:03:46.063 that we think of as distinctively musical, where we're listening along with the sound, 00:03:46.063 --> 00:03:49.632 engaging imaginatively with the note about to happen. 00:03:49.632 --> 00:03:54.150 This mode of listening ties in with our susceptibility to musical ear worms, 00:03:54.150 --> 00:03:56.660 where segments of music burrow into our head, 00:03:56.660 --> 00:04:00.089 and play again and again, as if stuck on repeat. 00:04:00.089 --> 00:04:03.109 Critics are often embarrassed by music's repetitiveness, 00:04:03.109 --> 00:04:05.382 finding it childish or regressive, 00:04:05.382 --> 00:04:09.752 but repetition, far from an embarrassment, is actually a key feature 00:04:09.752 --> 00:04:14.109 that gives rise to the kind of experience we think about as musical.