A new study of monkeys shows our relatively close relatives react emotionally to music. Some they found soothing, and relaxed as they listened. Other music sounded threatening, and the monkeys became agitated. But the monkeys only responded to music specially written for them, and didn't respond at all to a variety of music written for humans.
Can music change your emotional state? Many music lovers would say yes, and they would agree that listening to Samuel Barber's "Adagio for Strings" puts you in an entirely different emotional place than, say, Metallica.
Responding to music is something that humans all over the world, in perhaps every culture, have done for thousands of years ... maybe as long as there have been human beings.
But what about non-humans?
University of Wisconsin psychology professor Charles Snowdon has just published the results of an experiment designed to find out.
"David Teie, my collaborator, is a cellist with the National Symphony [Orchestra] and he's also a composer," Snowdon explained. "And he's also been thinking really hard about how does music have an emotional impact on us human beings. And he has come up with some theoretical ideas about the tricks that composers can use to make music have an emotional effect on us."
It turns out that composers have, perhaps inadvertently, been adapting some of the ways we use pitch and tempo in speech - in addition to the words we use.
"So if I'm talking to a baby, I'll say 'Awww, I'm sorry,' and to soothe a child who's upset we use long, slow notes that start at a high pitch and go down. If I want to get a dog or a child active and doing something, I'll say 'Come on, come on, let's go, let's go.' And they're short, very short bursts of sound that start at a low pitch and go up to a high pitch."
Snowdon oversees a research collection of copper-top tamarins, a monkey native to Colombia, and in the experiment, the monkeys got to listen to Samuel Barber and Metallica and some other music that, in humans, would prompt particular emotional responses.
"With the calming music, we should see them get calmer, move less, maybe eat more. If we're playing arousing music, they should move much more, they should show anxious behaviors. And what we found basically was that they showed none of those types of responses to the human-based music."
So classical music, heavy metal, does nothing for tamarin monkeys. But what if a composer — like maybe Snowdon's collaborator, David Teie — wrote some music specifically designed to appeal to a simian listener. How would you approach that?
"We recorded a lot of vocalizations from the monkeys, and the pitches are typically about three octaves higher than they are in humans, and their tempos are about twice as fast as human speech or music would be. So knowing that the monkeys had a different pitch range and a different tempo, David composed pieces that were based on their calming vocalizations and based on their threat or arousing vocalizations — to basically cover those acoustic principles that he thought were important in inducing emotions."
Charles Snowden and David Teie report the results of the work in the journal Biology Letters.
One thing not mentioned in the published paper: how the monkeys might react to non-Western music. Snowden said he didn't test that but he speculates that the copper-top tamarins wouldn't have any more emotional reaction to Indian ragas or Javanese gamelan music than they did to the Western music they heard.