Reviewed by Hansa D. Bhargava, MD on September 14, 2018
From the WebMD Archives

Sept. 14, 2018 -- Every parent has stories about a moment their 2-year-old surprised them.

Silvia Thoet is amazed that her 21-month-old bilingual daughter already understands that her parents talk to her in two different languages. “My husband doesn’t speak Spanish. I noticed that she knows that already because when she talks to him in Spanish, she immediately corrects herself and talks to him in English,” she says. “It’s amazing.”

Karly McBride was astounded when her 21-month-old daughter got upset with her aunt who was using the same kind of blue water bottle she normally sees her mother drinking from. “She thought my sister took my water bottle and kept taking it from my sister, giving it to me and saying, ‘Mommy’s cup.’ ”

And the surprising moment for Danette Zeh came in the middle of the night when her 2-year-old son woke her up by roaring loudly next to the bed where she and her husband were fast asleep. “He told us he was a baby T. rex and they are nocturnal hunters,” Zeh recalls. She thinks the young boy learned the word “nocturnal” from a National Geographic documentary the family had been watching.

It’s not just parents that are amazed by what 2-year-olds know. More and more, researchers are, too.

More than 2 decades ago, scientists at the University of Kansas found that on average, low-income children knew 30 million fewer words than affluent kids, and that the way and amount the parents talked to their children played a direct role in that gap. The quality of adult communication with the kids affected their IQ, vocabulary, and the way they learned. Today, the Thirty Million Words research program at the University of Chicago teaches parents and caregivers in the community ways to strengthen children’s language to help their brains develop.

Now, new studies on toddlers are giving more interesting insights into just what a 2-year-old knows.

“Infants’ understanding of the social world is much more sophisticated than was previously thought,” explains Francesco Margoni, PhD, a post-doctorate researcher at the University of Trento in Italy.

He’s the lead author of a study published in September that found that 21-month-olds are able to distinguish between leaders, whose power comes from the respect of others, and bullies, who are powerful because people fear them. The toddlers have different expectations about how people will respond to the two.

“This really is pretty sophisticated thinking,” Margoni says.

Leaders vs. Bullies

In the study, 21-month-old children watched cartoon characters in a variety of scenarios in which a leader or a bully gave orders to other characters. Researchers interpreted results based on where toddlers looked and what drew their attention -- an approach often used when children can’t talk.

They found that when the leader gave the order, the toddlers expected the other cartoon characters to obey, even when the leader had left the scene. But when the bully gave the order, the toddlers didn’t have an expectation of how the cartoon characters would behave.

Only when the bully stayed around after giving the order did the study subject expect the characters to obey, to avoid being harmed.

Margoni says this shows children understand that leaders are expected to be obeyed even when they aren’t still in the room, but bullies are expected to be obeyed only as long as they remain present and can enforce their demands. Still, researchers stress this doesn’t mean 21-month-olds necessarily have the impulse control to behave this way.

It does suggest, he says, that “infants understand something about how authority figures should be treated, and about the obedience that is owed to them, and this is something that parents and caregivers can build on when interacting with children, by reminding them of what they already know.”

Another study published this month finds that by the time children are 24 months old, they know when people are judging them and are capable of changing their behavior to get a positive response from their evaluator.

“Prior to this study, most researchers would propose that this ability would emerge around 4 years of age,” explains lead author Sara Valencia Botto, a PhD candidate at Emory University in Atlanta. “The fact that 14- to 24-month-olds are encoding other people’s reactions to behaviors and objects and using that information to change their behavior when others are watching is quite sophisticated.”

Botto conducted experiments on more than 100 children between the ages of 14 and 24 months. Using a remote-controlled robot toy, researchers saw if there were differences in how children acted when they were observed by an adult and when that adult turned away and pretended to read a magazine. They found that toddlers were less inhibited while playing with the toy when they weren’t being watched and appeared more embarrassed when they were seen.

These and other exercises with similar findings mean that toddlers “take into consideration the other person’s evaluation in relation to their own behavior,” explains Philippe Rochat, PhD, a professor of psychology at Emory University and second author on the paper.

“When you look at a 15-month-old or 24-month-old, they may seem like they are in their own little world,” Botto says. “But our research shows they are very attentive to others, their behavior, and their preferences, and they are using this information to regulate their own behavior.”

What Else Can 2-Year-Olds Do?

According to the CDC, 2-year-olds’ milestones include mimicking people, showing independence and defiance, following instructions, and repeating words that are overheard. Karen Hamilton, a preschool music and yoga teacher, says she has routinely seen this and more while teaching 2-year-olds yoga poses and songs involving words and sign language.

“They surprise me all the time,” she says. “I’m always so amazed at what they pick up. They soak up everything. I love watching 2-year-olds grow.”

Research has shown that around the age of 18 months to 24 months, children start helping, answering and responding to requests, and cooperating. Studies have shown that 2-year-olds prefer people with helpful actions over harmful ones, they can actively cooperate toward shared goals, and they understand the difference between trying to do something and just pretending to do it while playing.

Henry Wellman, PhD is a developmental psychologist at the University of Michigan who has specialized in children’s cognitive development for 30 years. His research has shown that 2-year-olds pick up on other people’s preferences, understand others’ desires and emotions, know the appropriate name or word for many objects, and can tell when someone says it incorrectly and even correct them. He says he and his team have also discovered that there is a universal environment that helps children come to understand the world, but differences in those environments can affect the speed with which children learn.

“We used to target 4- and 5-year-olds with our research because we thought they were the ones we had been mischaracterizing in terms of what they know. But over the years, research has proceeded to younger and younger kids,” Wellman explains. “Two-year-olds can have really interesting and surprising ideas and not necessarily the same ideas we would have.”

Toddlers and Technology

Guidelines from the American Academy of Pediatrics urge parents and caregivers to avoid digital media use for children under 24 months old -- except for video chatting. The group says young children need “hands-on exploration and social interaction with trusted caregivers to develop their cognitive, language, motor, and social-emotional skills.”

While the group believes the benefits of media are limited for those under 2, its guidelines do point out that emerging evidence shows children can learn words while live video-chatting with a responsive adult.

Lauren J. Myers, PhD, has focused much of her research on this. One study published in 2017 by the assistant professor of psychology and her team at Lafayette College in Pennsylvania found that starting around 17 months, children could form relationships with a new person over video chat and learn from that person when the discussions were on video chat -- but not when they were pre-recorded.

“Live video chat mattered,” Myers says. “Children recognized and preferred the person they had video-chatted with but did not prefer the person that was pre-recorded. They behaved in a more interactive, back-and-forth manner with the person who could see and hear them on video chat. They would try to do that with the pre-recorded person, but they realized it didn’t match up quite as well.”

Even so, in another study published in February 2018, Myers and her team report that children ultimately learn more from someone in the room with them than from a person on the other end of a video chat. In this study, adults in the room with a child would either engage or ignore a person on the video chat, and researchers found that toddlers would mimic whatever the adult in the room with them did.

“Children at this age love imitating adults, and they are very astute observers of their social worlds. But what children really used as their source of information was the adult sitting next to them,” Myers says. “It speaks to the importance of really observing your children sensitively and not assuming they necessarily understand that the grandma on the screen is the same one who comes to visit.”

Myers says the bottom line is that 2-year-olds are smart and can pick up on subtle social cues. But more than anything, they learn from the adults around them.

“Caregivers are really important,” she says. “Children need their adults to help them unpack and understand how they should act and react. They are really looking for guidance from the adults in their world.”

Show Sources

Karen Hamilton, preschool music and yoga teacher, Springfield, VA.

Fiona King.

Francesco Margoni, PhD, post-doctorate researcher, University of Trento, Italy.

Karly McBride, mother.

Lauren J. Myers, PhD, assistant professor of psychology, Lafayette College, Easton, PA.

Philippe Rochat, PhD, professor of psychology, Emory University, Atlanta.

Silvia Thoet, mother.

Sara Valencia Botto, PhD candidate, Emory University, Atlanta.

Henry Wellman, PhD, developmental psychologist, University of Michigan, Ann Arbor.

Danette Zeh, mother.

Developmental Psychology: “Sensitivity to the evaluation of others emerges by 24 months.”

Child Development: “Becoming a social partner with peers: cooperation and social understanding in one- and two-year-olds.”

Nature: “Social evaluation by preverbal infants.”

PNAS: “Infants distinguish between leaders and bullies.”

Developmental Science: “Baby FaceTime: can toddlers learn from online video chat?”

Journal of Children and Media: “Eyes in the room trump eyes on the screen: effects of a responsive co-viewer on toddlers’ responses to and learning from video chat.”

Psychological Science: “Young children use statistical sampling to infer the preferences of others.”


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