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Hand gestures affect the way people hear you

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Making simple up and down hand movements while speaking may influence the way people hear what you are saying.

We often use meaningless movements, such as flicking or waving our hands, known as beat gestures when speaking face to face. These typically align with prominent words in speech.

“Politicians use these gestures all the time to get their message across,” says Hans Rutger Bosker at the Max Planck Institute for Psycholinguistics in Nijmegen, the Netherlands.

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Bosker and his colleagues tested how important these movements are in influencing sound recognition. They presented Dutch participants with videos of Bosker saying Dutch words that have two meanings depending on which syllables are stressed – an example in English would be the difference between object and object. Bosker paired each word with a beat gesture either on the first syllable or the second syllable.

The team found that participants were on average 20 per cent more likely to hear stress on a syllable if there was a beat gesture on it. Mismatched beat gestures also biased what they heard, with 40 per cent of participants hearing the wrong sound.

“The timing of even the simplest hand movement is vital to face-to-face communication,” says Bosker. “We’ve shown how multimodal speech perception really is,” he says.

This could be a learned association, but there could be an evolutionary reason behind it says Wim Pouw at Radboud University in Nijmegen, who wasn’t involved in the research. “Manual gestures, like those with a beat quality, interact with the vocal system by using muscles that can increase lung pressure. This affects vocal qualities associated with stressed speech,” says Pouw. He suggests that observing these gestures helps us to perceive these changes in vocal qualities.

Although only tested in Dutch, Bosker says similar effects may be seen in other similar languages such as English, and may even be present in all languages. “This effect could be generalised to much more than just Dutch, but this is highly speculative,” he says.

Bosker says that his research is even more important during the current coronavirus pandemic. “With people wearing face masks, we can’t lip read. Our data explains how much communication can be improved if we gesture along,” he says.

Journal reference: Proceedings of the Royal Society B, DOI: 10.1098/rspb.2020.2419

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