Gestures influence the way our brains process grammar

Our hands may do more than complement what we say. They can also help our brains process grammar. In a new neuroimaging study published in PNAS, researchers from the Max Planck Institute for Psycholinguistics (MPI) in Nijmegen show that gestures can make it easier to process negative sentences (“I did not sleep”), providing the first neurocognitive evidence that gestures influence grammatical processing.

To understand spoken language, facial expressions, tone of voice and gestures are important. For instance, when someone makes a drinking gesture, it is easier to understand the word “drink.” But do gestures also help with understanding negation, the grammar of negative sentences?

“Understanding negation is cognitively demanding because it requires us to recognize that something is not the case, rather than simply processing what is directly presented,” said Hatice Zora, the study’s first author.

“Yet negation is used very frequently and is one of the first linguistic phenomena that children learn to express. We still do not fully understand how people process negation when it is conveyed through multiple channels of communication, or how the brain processes negation. In this study, we tested whether speakers’ gestures ease the processing of negated sentences.”

Variation in multimodal negation across languages

In many languages, words like “not” precede the verb (“I did not dig”). In Turkish, the word for “not” follows the sentence-final verb (“kaz-ma,” meaning “dig-not”). This means that Turkish listeners have to wait slightly longer for information that negation is coming up than speakers of languages with early negation marking.

Gestures for negation also vary widely across cultures, ranging from a head shake to eyebrow frowns and hand movements. Turkish speakers frequently use a backward hand flip to indicate “not,” typically before the negation marker “ma.” Stress on the verb is another cue that negation is coming up. But do these early cues from gestures and intonation make negative sentences easier to process—especially in a language like Turkish?

The brain processes negative gestures before negative words

The researchers asked 24 native Turkish speakers to listen to negative sentences while their brain activity was recorded with EEG (electroencephalography). In some trials, the negative sentences (“Ferit did not dig the garden”) had only a stress shift or a gesture. In other trials, the sentences had both cues or neither. This way, the team could examine how the brain responds when cues for negation are presented separately or work together. The researchers used digital avatars to present the stimuli to carefully control the different cues.

Adding a gesture indeed made processing negative sentences easier. The stress cue was helpful only when combined with the gesture. “In languages where negation is expressed after the verb, gesture and prosody offer a helping hand,” said Asli Ozyurek, lead investigator of the study at the Multimodal Language Department. “Gestures might be more effective in some languages than others, depending on their grammar,” Ozyurek added.

“Further studies are needed to see whether gestures and intonation help process negation in all languages or whether this is a form of multimodal diversity that has evolved to optimize and ease processing in languages with postverbal negation.”

Gestures as part of grammar

When a grammatical marker arrives late, gestures may provide early access to relevant grammatical information. This means that gestures may be an inherent part of grammar.

“Our research provides the first neurocognitive evidence that gestures influence how our brains process grammar,” Zora said. “Grammar is not processed in isolation but emerges from the brain’s ability to integrate multiple communicative signals in real time. Gestures, then, can be considered part of grammar.”

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Robert Egan

Bachelor’s in mathematical biology, Master’s in creative writing. Well-traveled with unique perspectives on science and language.

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