How “Highways” in the Brain Help Young Children Form Plurals

Have you ever heard a child proudly announce in German, “Schau mal, zwei Hünde!” What sounds amusing to us adults clearly shows just how difficult forming plurals still is for a three-year-old. The child has already understood that there is a rule (for example, adding an “e” to the German word for dog, “Hund”, makes the plural “Hunde” but also uses an umlaut similar to the German plural for hands “Hände”) and that it’s not just a matter of learning a new word. After all, the child has certainly not heard “Hünde” yet; they just aren’t applying the plural rule quite correctly yet. Cheslie C. Klein, Philipp Berger, Charlotte Grosse Wiesmann, and Angela D. Friederici from the Max Planck Institute for Human Cognitive and Brain Sciences (MPI CBS) have now investigated in a study to what extent the maturation of neural pathways in the brain is linked to children’s ability to form the plural of words.

 

 

• Plurals in Language: Young children struggle to form plurals, as shown by a study from the Max Planck Institute for Human Cognitive and Brain Sciences. They understand rules but often misapply them.
• Neural Pathways: Researchers explored how the maturation of neural pathways affects children's ability to form plurals. Specific nerve fiber connections, like the arcuate fascicle, are crucial for language processing.
• Research Findings: The study highlighted the importance of connections in the arcuate fascicle and the premotor cortex for preschool children, differing from adults, who rely more on auditory skills. This understanding sheds light on how children master plural formation.

“In adults, we know that very specific nerve fiber connections in the brain are responsible for this,” explains lead author Cheslie C. Klein. “Like highways, they ensure that information travels at lightning speed from one brain region to another, where it can be processed together to form language. The so-called arcuate fascicle plays a key role in this process. It connects the grammar center in the frontal lobe with the temporal lobe, where words and their meanings are integrated with the relevant grammatical rules. Since this connection doesn’t fully mature until relatively late in life, we wanted to find out in our study: Does this neural highway already play a role in the young brain, enabling preschool-aged children to learn the plural forms of words?”

For their study, the researchers examined a total of 120 children aged three to five. To test how well the children could already form plurals, they played fun language games at the MPI CBS. During these games, the children were shown pictures of single objects or groups (for example, several dogs) and were asked what they could see. Cheslie C. Klein explains: “The key point here is that the children were shown words they already knew, but also completely made-up words—such as a ‘wug.’ This allowed us to check whether the children truly had the plural rule in mind and could apply it to the new words—‘two wugs’—rather than just repeating familiar words from memory.”

In addition, the researchers used magnetic resonance imaging (MRI) to examine the neural connections in the brain. They wanted to know: Is the maturity of these “highways” directly related to how well a child has already mastered the plural rules? “Our findings reveal an intriguing shift in development between the ages of three and four,” explains Charlotte Grosse Wiesmann, head of the research group “Milestones in Early Cognitive Development”. “While no direct correlation between the maturity of the arcuate fascicle and the ability to form plurals was observed in three-year-olds, this changed significantly in four- and five-year-olds. Here, the maturity of this nerve fiber tract was directly correlated with the correct application of plural rules. This means that the better connected this ‘highway’ was, the more confidently the children could apply the rules.” Last author Angela D. Friederici adds: “Unlike in adults, in preschool children, not only was the part of the arcuate fascicle leading to the language center in the frontal lobe important, but also the part extending into the so-called premotor cortex. In adults, this area is actually more responsible for hearing and repeating words—a skill that may also have helped them imitate the plural form of words rather than deducing it based on abstract grammatical rules. The results thus help us understand how children can seemingly effortlessly reach the milestone of transforming ‘Hund’ into ‘Hunde’”.