Scientists talked about the role of gestures in understanding grammar

Hand gestures can not only complement the meaning of individual words, but also participate in grammar processing. In an experiment with native Turkish speakers, a characteristic hand movement helped the brain prepare in advance for negation even before the corresponding grammatical indicator appeared. Why negative sentences require additional effort and whether gestures can be considered part of grammar is in the "Izvestia" material.

How gestures help you understand speech

During a conversation, a person perceives not only words. The understanding of what is said is also influenced by intonation, facial expression, gaze direction and hand movements. These signals can complement speech, emphasize individual elements of a statement, or suggest in advance what the other person is going to say.

Previous research has shown that gestures make it easier to understand the meaning of individual words. For example, a characteristic hand movement can help the listener to recognize the verb "drink" faster or to understand what the speaker is referring to.

However, it remained unclear whether hand movements were capable of influencing not only the meaning of words, but also the grammatical processing of a sentence. The authors of the new work decided to test this using the example of negation, one of the basic operations of human language.

Why is Denial harder to process

An affirmative sentence tells you what has happened or exists. The negative construction requires an additional operation: the listener needs to form an idea of the event, and then understand that it did not take place.

For example, when perceiving the phrase "Ferit dug up a garden," the brain processes the described action. In the sentence "Ferit did not dig up the garden", he needs to additionally take into account the negation and adjust the initial model of the situation.

At the same time, negative constructions are constantly used in everyday speech and are among the first linguistic phenomena that children master. According to the researcher, scientists do not yet fully understand how the brain combines words, intonation and gestures when processing such sentences.

Why did scientists choose Turkish?

The position of negation in a sentence varies depending on the language. "Russian" and "English" usually have a negative particle before the verb: "did not sleep" or "did not sleep." Due to this, the listener receives information early enough that the offer will be negative.

The Turkish language works differently. The predicate is usually found at the end of a sentence, and negation is expressed using the suffix -mA, which is attached after the verb base. Therefore, the listener has to wait longer for a grammatical signal confirming the negation.

However, negation in Turkish can be transmitted not only morphologically. The stress changes before the negative suffix, and the speaker can make a common gesture — to take or turn his hand back. Such a movement often appears even during the pronunciation of the verb base, that is, before the listener hears the negative suffix.

This allowed the scientists to test whether the brain uses early visual and intonational cues to predict subsequent grammatical construction.

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Scientists claim that they have learned to predict changes in speech.

How did the experiment go?

24 native Turkish speakers participated in the experiment. They listened to the negative sentences while watching the digital character. Using an avatar allowed the researchers to precisely control hand movements, facial expressions, and the timing of each signal.

The proposals were presented in four versions. In some cases, the negation was preceded only by a gesture, in others by a change in stress. Combinations were also used in which both signals were present or none of them were present.

The participants could hear a sentence corresponding to the phrase "Ferit did not dig up the garden." At the same time, under different conditions, the avatar accompanied the verb with a negative gesture, emphasized it intonationally, combined both signals, or pronounced a sentence without additional prompts.

Brain activity was recorded using electroencephalography. This method allows you to record small changes in electrical activity and determine how quickly the brain reacts to individual elements of speech and images.

What showed the brain activity

The researchers paid special attention to the components of the N100 and N400 brain response. They occur after the presentation of a certain signal, but reflect different stages of its processing.

N100 appears approximately 100 ms after the event and is associated with early perception of noticeable visual or auditory changes. In the experiment, a negative gesture caused a pronounced N100 reaction. According to the authors, this is due to the fact that the movement of the hand itself attracted the attention of the participants.

More important results were obtained by analyzing the N400. This component is usually associated with processing meaning, human expectations, and embedding new information into an already formed context. The more unexpected or difficult it is to integrate an element of utterance, the more noticeable the N400 response may be.

When the negative suffix was preceded by a corresponding gesture, the amplitude of the N400 decreased. The researchers interpreted this as a sign that the brain had received information about negation in advance and therefore spent less effort on processing the grammatical indicator. Thus, the movement of the hand did not just repeat what had already been said, but made it possible to predict the structure of the sentence before the negation was fully expressed in words.

Why was intonation alone not enough?

A change in stress could also indicate an approaching negation. However, by itself, it did not provide the same ease of processing as the gesture.

The intonation prompt increased the decrease in N400 only when there was simultaneous hand movement. In other words, the brain used the sound signal in combination with the visual signal most effectively.

The researchers suggest that the gesture turned out to be a more visible and reliable indicator of denial. Intonation changes may be less obvious, especially if the listener needs to simultaneously follow the meaning of the words and the structure of the sentence.

Aslu Ozurek, head of research at the Department of Multimodal Language at the Max Planck Institute of Psycholinguistics, noted that in languages where negation appears after the verb base, gestures and prosody can provide the brain with the necessary information in advance.

Can gestures be considered part of grammar?

Grammar is usually associated primarily with words, endings, suffixes, and the order of elements in a sentence. A new study shows that during live communication, the brain can process grammatical information through several channels at once.

The gesture in this case does not just illustrate the meaning of the statement. It predicts a specific grammatical operation — negation — and changes the brain's response to the subsequent morphological indicator.

According to the authors, this is the first neurocognitive evidence that gestures can influence grammar processing, not just understanding the meaning of individual words. The results support the idea of language as a multimodal system in which speech, intonation, facial expressions, and body movements are processed together.

However, this formulation should be understood as a scientific interpretation of the data obtained, and not as proof that any hand movement is a grammatical sign. The only thing that matters is a gesture that is understandable to native speakers of a particular language and is consistently associated with a specific linguistic construct.

Does this mechanism work in other languages?

So far, the results relate only to the Turkish language and one type of negative gesture. In languages where the negative particle appears before the verb, hand movements can give the brain less additional information, since negation becomes known early enough.

The gestures themselves also differ. In one culture, denial is expressed by moving the brush, in another by shaking the head, raising the eyebrows, or by a combination of several signals. The same gesture may also have different meanings in different countries.

The authors intend to find out whether gestures and intonation make it easier to process negation in languages with a different grammatical structure. This will allow us to determine whether we are talking about a universal mechanism or a method that is especially important for languages with late denotation of negation.

Where the results can be useful

The study helps to better understand how a person perceives spoken language in real conditions. In ordinary conversation, words rarely exist separately from facial expressions, gazes, and body movements, but many language models traditionally consider primarily an audible or written signal.

In the future, the results can be taken into account when learning a foreign language, developing digital teachers, conversational systems and virtual characters. If gestures really communicate grammatical information in advance, using them correctly can make artificial speech more understandable and natural.

The work may also be of interest to specialists studying speech disorders and its perception. However, the authors have not tested the methods of training or rehabilitation, so it is too early to talk about the practical effectiveness of such approaches.