A good song can easily get a listener nodding their head or tapping their foot along to the beat. While you may not initially realize you're doing it, those physical responses to music are still conscious decisions that you can stop whenever you want. According to neuroscientists, however, music also has the ability to influence even some of our involuntary movements. In a study published on November 18 in the journal PLOS Biology, researchers demonstrated humans will often even start blinking in time with a song.
Humans blink a lot. The rate varies by person, but your eyelids flutter 900 to1,200 per hour. That adds up to as many as 19,200 blinks per day, 134,400 a week, and an eyewatering 7.1 million times a year. It's a good thing, too. Blinking keeps the eyes moist and oxygenated, removes debris, and protects against many injuries. There's no way our species could go about our daily lives if all those blinks required conscious effort, so evolution long ago designated blinking as one of our many involuntary bodily functions.
However, that doesn't mean blinking isn't susceptible to outside influences. At the Chinese Academy of Sciences, researchers measured spontaneous blinks of more than 100 volunteers as they listened to Western classical music featuring steady, easy-to-follow tempos. They soon discovered that participants' eyelid activity quickly aligned with the music. What's more, even brainwaves synced during song sessions.
"What surprised us most was how reliably a 'small-movement' like blinking locks to the beat -- it's a tiny action that reveals a deep coordination between hearing and action, which we did not expect at all," study coauthor Yi Du said in a statement.
The participants weren't trained musicians, either, meaning that this example of auditory-motor synchronization wasn't a byproduct of prior experiences. To further demonstrate the brain's ability to sync with songs, Du's team played the same songs backwards while measuring blink rates. Even then, eyelid movement aligned with the tempos, indicating that familiarity with particular songs doesn't influence blinking speed. Researchers then played a single tone featuring a beat mimicking actual music. While blinking rhythm slightly worsened in these backwards song trials, it wasn't statistically significant.
The auditory-motor synchronization does appear to have some limits. The study's authors noted the alignment is often disrupted when you're also doing an unrelated task. During a separate phase of the experiment, researchers asked participants to listen to songs and wait for a red dot to appear on a screen. They theorized the volunteers would likely recognize the dot faster if it appeared in tempo with the music. Instead, blinking unmatched from songs regardless of when the dot became visible. This implies some level of focus is still required for blinking to mirror a song's beat.
"What surprised us most was how reliably a 'small-movement' like blinking locks to the beat," said Du. "It's a tiny action that reveals a deep coordination between hearing and action, which we did not expect at all."
These discoveries reverberate beyond simply learning more about music's influence on the human mind. Previous research has suggested some neurological conditions affecting physical movement could be alleviated by music-based therapies focused on auditory-motor synchronization. Gaining a better understanding of involuntary reactions to musicality may help advance future treatments in the field.
"I loved that a simple, non-invasive signal-blinks-can act as a window into rhythm processing. It opens doors for studies outside the lab," said Du. "This project reminded us that small, overlooked behaviors can expose big principles of brain function."