Do you sometimes ignore your mom while chatting with friends? If you’re a teen, that’s fairly common. And a new study may explain why so many adolescents tune out their moms’ voices.

Science has shown that young children’s brains are well adapted to their mothers’ voices. But as children grow into teenagers, everything is changing. The latest research shows that teenagers’ brains are now more adapted to the voices of strangers than their own mothers. This is what Daniel Abrams explains, who is a neuroscientist at Stanford University School of Medicine in California.

Abrams and his colleagues already knew that younger kids’ brains respond more strongly to their moms’ voices than to a stranger’s. “In adolescence, we show the exact opposite of that,” Abrams says. For teens, these brain regions respond more to unfamiliar voices than to their moms’. This shift in what voice arouses interest most seems to happen between ages 13 and 14. That’s when teenagers are in the midst of puberty (青春期), a roughly decade-long transition to adulthood.

These areas in the adolescents’ brains don’t stop responding to their moms, Abrams says. It’s just that unfamiliar voices become more rewarding and worthy of attention. Here’s why: As kids grow up, they expand their social connections way beyond their family. So their brains need to begin paying more attention to that broader world.

“As we mature, our survival depends less and less on maternal (母亲的) support,” says Leslie Seltzer, a biological anthropologist at the University of Wisconsin-Madison. She was part of the team that carried out that 2011 study. Instead, she says, “We rely more and more on our peers — friends and others closer to our own age.”

Abrams said that although teenagers and their parents sometimes feel frustrated with missing information, it doesn’t matter. “This is the way the brain connects, and there is good reason.”

【小题1】What do the underlined words “tune out” in Paragraph 1 mean?

A．Show respect to.

B．Cooperate with.

C．Pay little attention to.

D．Sing in tune with.

【小题2】How do teenagers behave differently from their childhood?

A．They are familiar to their mothers’ voices.

B．They are more excited hearing their mothers’ voices.

C．They respond more strongly to strangers’ voices than to their mothers’.

D．They deliberately ignore their mothers out of a desire to be independent.

【小题3】Why is there a change in teenagers’ response to their moms’ voices?

A．Their brains just stop responding to their moms.

B．Their moms’ voices bring them a strong sense of frustration.

C．Their moms’ voices are no longer rewarding and worthy of attention.

D．Their brains need to pay more attention to social connections outside their family.

【小题4】What does Abrams think of the change in family relations?

A．Disturbing.

B．Inspiring.

C．Insignificant.

D．Disappointing.