Not everyone can tap out a beat, but new research suggests that everyone has a drummer hiding deep inside the recesses of their nervous systems. According to a new study, scientists studying how humans process information have found evidence that indicates our brains can pick up on rhythmic patterns, even when we’re not paying attention to the music.
In a new study published in the journal Brain and Cognition, researchers from the University of Groningen in the Netherlands sat 20 psychology students in front of a computer and had them complete a task involving pressing the spacebar on a keyboard as fast as they could. But that was just a distraction—the real test had to do with the music the researchers were piping into the room and the response from the students’ eyes.
"The perception of music is a complex interaction between what we hear and our interpretation," the researchers write in the study. "This is reflected in beat perception, in which a listener infers a regular pulse from a musical rhythm."
Throughout the test, the researchers played one of several audio clips that sounded like drum rhythms you might hear in a pop or rock tune. Several of the songs, however, left out particular beats throughout the clip: some were missing a bass note here or there, others were missing hi-hat clicks. Meanwhile, a camera trained on the subject’s eyes recorded the movement of their pupils in order to see how they responded to the missing beats.
Because people can’t consciously control how big their pupils get, studying this movement can help shed light on how we perceive the world. For instance, in this study, the researchers found that even when the subjects were ignoring the music, their pupils would get larger when a beat was dropped. In addition, they found that the subjects’ eyes reacted differently when different beats were missing—a missing bass note played on a beat would provoke a bigger reaction than a missing syncopated hi-hat tap, for example. According to the study, that suggests that people not only have a basic sense of rhythm, but they can distinguish between more important notes on an unconscious level.
“People have very little control over their pupillary response,” Bruno Gingras, a researcher at the University of Innsbruck’s Institute of Psychology, who was not involved with this study, tells Smithsonian.com. “People have used other methods to show that people react if they hear a surprising chord, or a surprising note. But so far it has not really been shown with pupillary dilation.”
In recent years, scientists have begun looking to pupillary movement to glean new insights into the brain. While they have long known that pupil size and movement is an unconscious reaction to stimuli like light and sound, it was only once cameras and software became sensitive enough that researchers were able to start thinking about the eyes as a window into the recesses of our brains.
“Physiologic signals in general are quite noisy,” Gingras’ research partner Manuela Marin, who was also not involved with this study, tells Smithsonian.com. “Even if you have other autonomic nervous system measures, like skin conductance, you need very good technology to show the effects.”
Pupillary movement, on the other hand, is pretty obvious. After all, with a simple camera, researchers can gauge a person’s unconscious reaction to something just by tracking how big their pupils get, even as they perform another task.
While Gingras and Marin say this study presents some intriguing evidence for humans having an innate sense of rhythm, it would be interesting to see how professional musicians would respond to a similar test. They suspect that musical training and knowledge could spark a much stronger reaction to changes in rhythms and musical patterns than a psychology student who may not have spent as much time studying music in the same way. Applying this technique to different groups of people could help paint a more nuanced picture of how deeply ingrained music is in our unconscious minds.