It doesn’t work without grammar: when we speak, we don’t just string the words together arbitrarily. Instead, every language follows very specific systematic rules. Some of these grammatical principles apparently already master babies. As experiments suggest, children as young as eight months old can distinguish between so-called function words and content words. They seem to know intuitively that, for example, individual articles and conjunctions appear more often than content words – and in which order the two word categories are used in their mother tongue.
The speed at which children learn languages is a constant astonishment for parents and language researchers. They quickly save new words and recognize grammatical rules that link them together in a sentence. A basic skill is the distinction between so-called function words and content words. Unlike nouns, verbs and adjectives, functional words have no lexical, but only a grammatical meaning – for example, articles or conjunctions. Surprisingly, babies can distinguish function words from content words, as studies suggest. They obviously also know at which position in the sentence these words are normally located. For example, function words in German, English and French usually precede content words.
“Recognizing functional words is an important first step for children on the way to grammatical understanding of their mother tongue,” explains Caterina Marino from the University of Paris Descartes and her colleagues. But based on which characteristics do babies distinguish these word categories at all? A common hypothesis assumes that, in addition to the length, the relative frequency of the words also plays a role: Individual function words such as “that” or “they” appear frequently in most languages because there are fewer of these words than content words. The researchers have now examined whether this assumption is correct with 175 eight-month-old babies with French as their mother tongue.
Test with fantasy language
For the study, the young subjects were first played recordings of a fantasy language. Certain words appeared much more often than others – as is typical for function words. The sequence of function and content words corresponded to the grammar of their mother tongue. After this learning phase, there were various tests in which the children heard new sentences in the art language. Among other things, sentences were presented to them in which the order of function and content words was the same as in French. The other half of the sentences, on the other hand, was in the “wrong” order. How would the babies react? The scientists documented this on the basis of the gaze duration. Together with the audio recordings, the babies saw pictures on a screen. The length of time they looked at what they heard served as a crucial indication: a longer gaze meant a preference for this grammatical construction.
In fact, it was confirmed that the babies looked longer when there were frequent words before the less frequent ones. This pattern corresponds to the typical order of function and content words in French, as Marino and her team emphasize: “This preference must come from the knowledge that the function word comes first in the mother tongue.” Further experiments also revealed that the children introduced new ones Words of content gave more interest than new function words – as if they seemed to know that there can only be a limited number of words in this category. “Content words form an open class – new terms such as iPad or Brexit are added to the lexicon every day. In the case of functional words, however, such extensions are not possible without fundamental changes in the language, ”the researchers explain.
Little grammar experts
All in all, the observations show that babies who are already eight months old have a rudimentary sense of the correct grammar. You obviously already understand that there are words with different functions in a sentence – some denote objects or people, while others structure the sentence and show connections. In addition, they already know that individual function words appear more often in their mother tongue than content words and that they are usually in front of them in the sentence. “We are providing the first proof that children use the word frequency as an indication to form lexical categories”, Marino and her colleagues state. This is also interesting because children initially only use content words when learning to speak: “Eat!”, “Doll!”, “Papa!”. “Functional words, on the other hand, are generally added later,” the researchers explain. Nevertheless, the current study suggests that the sense for these auxiliary words must already be available at this point.
“This suggests that children have basic grammatical knowledge before they start speaking or have a larger vocabulary,” the scientists concluded. Interestingly, the ability to categorize words based on their frequency is also known from animals like rats. According to the researchers, this could therefore be a general mechanism of the brain.
Source: Caterina Marino (University of Paris Descartes) et al., Current Biology, doi: 10.1016 / j.cub.2020.01.070