William Britten / Getty Images

Ah, the terrible twos: in between those heart-warming moments of wonder and devotion are those tantrums over having to put socks on that define this year of development. But the latest research shows that if those outbursts continue past the terrible twos, they may be a sign of poorly developed language skills.

In a new study published in the journal Child Development, researchers draw links between communication skills that kids develop as toddlers and the emotional development that occurs during early childhood. The findings suggest that language and vocabulary at the earliest ages may lay a foundation for emotional regulation among children as they enter preschool and beyond.

(MORE: The Bright Side of Anger: It Motivates Others)

Psychologists at Penn State followed 120 young children, first surveyed as toddlers at 18 months, and then visited or interviewed them every six months until just after their fourth birthdays. The researchers tested and assessed the children’s early language skills, including their vocabulary when talking at home with their parents. Periodically, they would also test how well the kids dealt with frustration and anger, by presenting each child with a shiny gift-wrapped bag, closed with a ribbon. The kids were told they had to wait several long, boring minutes before they could open it. Then the researchers would watch the children’s reactions.

In the paper, the authors say that there’s good reason to suspect a link between language ability and managing emotion. They write:

[Y]oung children who acquire language quickly and well should be able to think about rules (“Mommy said wait”), to communicate needs calmly (language mitigates the need to express needs nonverbally), and, when needed, to sustain a shift of attention rather than focus on something they cannot have (language enriches the content of the activities, such as pretend play, that distract the child from the desired object or activity).

In fact, the results of the study seem to bear out that suspicion. “We found that toddlers who have stronger language skills than other toddlers, and whose language skills develop faster over time, tend to be better at regulating frustration when they’re preschool aged,” says Caroline Roben, lead author on the new study and now a postdoctoral researcher at the University of Delaware.

(MORE: To Really Read Emotions, Look at Body Language, Not Facial Expressions)

In particular, Roben says, the kids with good communication skills may be better at finding outlets for their frustration. By age 3, those kids with more developed language skills could ask their mothers calmly about a possible end to the waiting. Less developed kids, meanwhile, were ready to throw a fit, getting fussy and squirmy or otherwise acting out, presumably because they had less satisfactory ways of expressing their frustration in words. By age 4, the kids with more developed language were better at keeping themselves amused without toys — by talking and counting, or otherwise playing games by themselves.

Roben and her colleagues found the relationship occurred among both boys and girls, although in general, girls tend to develop language skills slightly faster than boys. In order to account for socioeconomic factors that could affect language development, the scientists enrolled children from households with roughly the same level of income, above the poverty line but below the national household average.

(MORE: More Sleep Means More Focused, Emotionally Stable Kids)

The findings suggest that children with stronger language skills may be better behaved as they get ready to enter preschool because they have the tools to describe and express their emotions, as well as stronger tools to cope with and distract themselves if they start to feel unhappy.

The scientists note, however, that it’s possible that rather than setting the stage for angry or aggressive behavior, slower language development may be a consequence of youngsters who are more angry and frustrated to begin with, possibly because they are distracted or because adults don’t enjoy interacting with them as much. It’s also possible that some still unidentified developmental process drives both the development of language skills and emotional growth.

(MORE: Want a Less Fussy, Easier-to-Sooth, Kinder Child? Make Music!)

Given the strength of the findings, however, Roben and her co-authors believe that it’s likely language has some impact on emotional development, and she hopes her findings could lead to interventions that improve kids’ emotional learning and potentially avert behavioral problems among youngsters.

“It’s well recognized these days that emotion regulation is important for success in school,” Roben says. Kids who can sit still, follow instructions and play well with their peers tend to get better grades than kids who are frequently distracted and aggressive.

Parents too might benefit from knowing about possible links between communication skills and basic emotional regulation. Not only is it a reminder that the terrible twos will eventually come to an end, it might also help parents focus on activities to advance their toddlers’ development.

“When you’re doing things to promote [your children’s] language skills, their verbal world, you may be doing something to promote their emotional development as well,” she says.