People using gestures while speaking may communicate more effectively as linguists believe that gestures and words very probably form a single "communication system" that serves to enhance expression.
"Gestures and words very probably form a single communication system, which ultimately serves to enhance expression intended as the ability to make oneself understood," said Marina Nespor, a neuroscientist at the International School for Advanced Studies (SISSA) at Trieste in Italy.
The researchers demonstrate the role of gestures in speech "prosody".
Linguists define prosody as the intonation and rhythm of spoken language, features that help to highlight sentence structure and therefore make the message easier to understand.
For example, without prosody, nothing would distinguish the declarative statement "this is an apple" from the surprise question "this is an apple?".
Even hand gestures are part of prosody, the researchers said.
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For the study, the researchers had 20 Italian speakers listen to a series of "ambiguous" utterances, which could be said with different prosodies corresponding to two different meanings.
"Gestures affect how meaning is interpreted, and we believe this points to the existence of a common cognitive system for gestures, intonation and rhythm of spoken language," Alan Langus from SISSA explained.
"In human communication, voice is not sufficient, even the torso and in particular hand movements are involved as are facial expressions," said Nespor.
The findings appeared in the journal Frontiers in Psychology.