Parental praise associated with longer toddler toothbrushing, a barometer of persistence

Using a first-of-its-kind video-based study, Penn and Yale developmental psychologists found that how parents talk to their 3-year-old during toothbrushing matters to the child’s behavior.

Adult holding a toothbrush standing with arm around toddler brushing teeth.

Any parent of a young child understands the battle of wills that daily toothbrushing can entail. Research led by the University of Pennsylvania’s Allyson Mackey and Julia Leonard of Yale University shows that parental praise during this task is associated with longer brushing, a barometer of the child’s persistence. They shared their findings in the journal Child Development.

“Persistence in early childhood has consequences for many life outcomes, from what children learn to whether they maintain friendships or reach their goals,” says Leonard, an assistant professor at Yale and former postdoc in Mackey’s lab, The Changing Brain. “It’s a really important skill for children to develop.”

A person standing on a stairwell, being photographed from above.
Allyson Mackey is an assistant professor in the Department of Psychology in the School of Arts & Sciences. She runs The Changing Brain Lab and is a researcher in MindCORE.

Most work in this area asks parents and children to come into a lab where researchers then study a behavior in the moment for a brief period. Mackey and Leonard wanted a more realistic situation.

They also knew it would be crucial to pick a task that wasn’t yet a full-blown habit for a toddler. “When you’re learning something, you use the cortex, but, once you’ve learned it, it transfers to subcortical areas of the brain. You can do the same thing over and over without having to think about it,” says Mackey, an assistant professor in the Department of Psychology and study senior author. “We wanted to study something more variable and more sensitive.”

In consultation with colleagues across Penn, including David Lydon-Staley in the Annenberg School for Communication, Angela Duckworth in the School of Arts & Sciences and Wharton School, and Dani S. Bassett in the School of Engineering and Applied Science, they landed on a design in which parents would record their 3-year-olds brushing teeth at home, each morning and evening, for 16 days in a row. Eighty-one families enrolled.

It’s the first time this kind of video-based paradigm has been used to study how young children behave during consecutive days. “This way of measuring kids every day gave us a window into people’s homes, into the interaction between parent and child,” Mackey says.

Rather than capturing a static picture, the work obtained something much more dynamic, adds Lydon-Staley. “To study things like emotions, cognitions, and behaviors, we need methods that move us outside of the lab,” says Lydon-Staley, an assistant professor of communication who runs Penn’s Addiction, Health, & Adolescence Lab. “You can learn something that’s more ecologically valid. With toothbrushing, you see natural fluctuations, how much it varies under natural conditions, and how much children get pushed by parent talk. You get to see life as it’s lived.”

What the researchers saw once they watched and analyzed the videos surprised them.

For one, parental behaviors mattered, the strongest effect the team discovered. When parents encouraged their children with words as simple as “good job,” rather than instructed with comments like “brush the backs” or “keep brushing,” children spent longer on the task.

Second, the researchers noticed that other factors—the parent’s stress level, the child’s mood, how much sleep the child had gotten the previous night—also played a role, though less so than parent talk.

Finally, a child’s persistence changed from one day to the next. “Our behavior and our children’s behavior varies every day, almost as much as it does from person to person,” Leonard says. “That’s just a really profound way to view human behavior. Even if we think we’re having a bad day, that could totally change the next day.”

Using the video-based approach and using toothbrushing as a measure of child response offer great tools for future work on persistence, according to Mackey, who says that these findings likely hold for other age groups and other tasks.

Beyond that, these approaches are key to determining more personalized interventions, for example, understanding the child who responds to praise compared to one who doesn’t but is sensitive to sleep disruptions. “If you can figure that out for your kid,” she says, “that’s the first and most critical step toward figuring out how to change behavior.”

Funding for this research came from a Jacobs Foundation Early Career Research Fellowship and from MindCORE at the University of Pennsylvania

Allyson Mackey is an assistant professor in the Department of Psychology in the School of Arts & Sciences at the University of Pennsylvania. She runs The Changing Brain lab and is a researcher in MindCORE.

Julia Leonard is an assistant professor in the Department of Psychology at Yale University.

Other University of Pennsylvania researchers who contributed to the work include Dani S. Bassett of the School of Engineering and Applied Science, Angela Duckworth of the School of Arts & Sciences and Wharton School, David Lydon-Staley of the Annenberg School for Communication, and from The Changing Brain lab, graduate student Anne Park, research specialist Sophie Sharp, and research assistant Hunter Liu.