June 2, 2005

Bouncing to the beat: how babies get their groove

McMaster University psychology graduate student Jessica Phillips-Silver and professor Laurel Trainor (right) measure 8 month old Taysia Potts' memory of sounds.

Hamilton, ON - Music makes us move to the rhythm. But just how are music and movement related? McMaster University researchers have found that how we move also shapes what we hear, even in babies.

“The simultaneous experience of listening and moving to a rhythm wires the brain so that different senses work together,” says Laurel Trainor, a psychology professor at McMaster. “Our interpretation of sound is affected not only by our auditory system but by input from our other senses as well.”

In a paper published in Science, Trainor and graduate student Jessica Phillips-Silver showed that the way 7-month-old infants interpret a rhythm is influenced by the way they are bounced to that beat. Trainor and Phillips-Silver played an ambiguous rhythm pattern to the infants that could be interpreted as a march (ONE-two-ONE-two-ONE-two!) if every second beat was accented or as a waltz (ONE-two-three-ONE-two-three!) if every third beat was accented.

One group of infants was bounced for two minutes in the arms of an adult on every second beat and another group on every third beat. After this experience, infants who had been bounced on every second beat preferred to listen to the rhythm with accents added to be a march (every second beat louder), while infants bounced on every third beat preferred to listen to the rhythm with accents added to be a waltz (every third beat louder). Preferences were measured by having infants control how long they listened to each version in a setup in which looking at one light turned on the march rhythm and looking at another light tuned on the waltz rhythm.

McMaster University psychology graduate student Jessica Phillips-Silver bounces to a rhythm with 8 month old Taysia Potts.

The researchers concluded that even though infants were presented with exactly the same sounds during the bouncing experience, the movement caused them to interpret and remember the rhythm differently: one group heard a march and the other a waltz.

“Across all cultures, caregivers naturally provide a rich rhythmic experience for their infants by rocking and bouncing them while singing,” says Phillips-Silver. “For the first time, we are able to show that this experience not only affects their emotional state, but also influences infants’ sensory development.”

McMaster University, named Canada’s Research University of the Year by Research InfoSource, has world-renowned faculty and state-of-the-art research facilities. McMaster's culture of innovation fosters a commitment to discovery and learning in teaching, research and scholarship. Based in Hamilton, the University has a student population of more than 23,000 and more than 112,000 alumni in 128 countries.