Young kids’ brains are especially tuned to their mothers’ voices. Teenagers’ brains, in their typical rebellious glory, are most decidedly not.
That conclusion, described April 28 in the Journal of Neuroscience, may seem laughably obvious to parents of teenagers, 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 reflect something much deeper than a punch line. As kids grow up and expand their social connections beyond their 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 his colleagues scanned the brains of 7- to 16-year-olds as they heard the voices of either their mothers or unfamiliar women. To simplify the experiment down to just the sound of a voice, the words were gibberish: teebudieshawlt, keebudieshawlt and peebudieshawlt. As the children and teenagers listened, certain parts of their brains became active.
Previous experiments by Abrams and his colleagues have shown that certain regions of the brains of kids ages 7 to 12 — particularly those parts involved in detecting rewards and paying attention — respond more strongly to mom’s voice than to a voice of an unknown woman. “In adolescence, we show the exact opposite of that,” Abrams says.
In these same brain regions in teens, unfamiliar voices elicited greater responses than the voices of their own dear mothers. The shift from mother to other seems to happen between ages 13 and 14.
It’s not that these adolescent brain areas stop responding to mom, Abrams says. Rather, the unfamiliar voices become more rewarding and worthy of attention.
And that’s exactly how it should be, Abrams says. Exploring new people and situations is a hallmark of adolescence. “What we’re seeing here is just purely a reflection of this phenomenon.”
Voices can carry powerful signals. When stressed-out girls heard their moms’ voices on the phone, the girls’ stress hormones dropped, biological anthropologist Leslie Seltzer of the University of Wisconsin–Madison and colleagues found in 2011 (SN: 8/12/11). The same was not true for texts from their mothers.
The current results support the idea that the brain changes to reflect new needs that come with time and experience, Seltzer says. “As we mature, our survival depends less and less on maternal support and more on our group affiliations with peers.”
It’s not clear how universal this neural shift is. The finding might change across various mother-child relationships, including those that have different parenting styles, or even a history of neglect or abuse, Seltzer says.
So while teenagers and parents may sometimes feel frustrated by missed messages, take heart, Abrams says. “This is the way the brain is wired, and there’s a good reason for it.”