As kids grow up, unfamiliar voices get more interesting

By Laura Sanders

Young kids’ brains are especially tuned to their mothers’ voices. Teenagers’ brains, in their typical rebellious glory, are most decidedly not.

That conclusion, reported on April 28 in the Journal of Neuroscience, may seem laughably obvious to parents of teens, including neuroscientist Daniel Abrams of Stanford University School of Medicine. “I have two teenaged boys myself, and it’s a kind of funny result,” he says.

But the finding may be deeper than a punch line. As kids grow up and expand their social connections beyond family, their brains need to be attuned to that growing world. “Just as an infant is tuned into a mom, adolescents have this whole other class of sounds and voices that they need to tune into,” Abrams says.

He and colleagues scanned the brains of 7 to 16-year-olds as they heard the voices of either their mothers or unfamiliar women. To focus the experiment on just the sound of a voice, the words spoken were gibberish.

Abrams and colleagues have previously shown that in kinds ages 7 to 12, certain regions of the brain – particularly those parts involved in detecting rewards and paying attention – respond more strongly to mom’s voice than a voice of an unknown woman. But in these same brain regions in teens, the new study finds, unfamiliar voices elicited greater responses than mom’s. The shift seems to happen between ages 13 and 14.

It’s not that these brain areas stop responding to mom, Abram says. Rather, the unfamiliar voices become more rewarding and worthy of attention. That’s how it should be, Abrams says. Exploring new people and situations in a hallmark of adolescence.

Voices can carry powerful signals. Biological anthropologist Leslie Seltzer of the University of Wisconsin-Madison and colleagues have found that when stressed girls hear mom’s voice on the phone, their stress hormones drop. The new results support the idea that the brain changes to reflect new needs, Seltzer says. Though, she notes, the results might change across varying mother-child relationships.

For now, teens and parents frustrated by missed messages can take heart, Abram says. “This is the way the brain is wired, and there’s good reason for it.”