Deaf People Are Faster at Recognising Body Movements

There is extensive research showing that Deaf people can quickly discriminate between Sign Language and non-Sign Language movements, and Deaf signers involve their sensorimotor systems in the perception of signs, although in a different way than hearing people who do not known Sign Language. The question, until now, was whether Deaf people could transfer this visual ability to the perception of other non-Sign Language movements and extract information from it. A new research shows that they can.

The perception of body movement is an important skill, as it helps to understand people's actions. So researchers at Gallaudet University wanted to see if Deaf people who are native in Sign Language have a greater sensitivity to human biological movements and if they can perceive these movements more quickly than hearing people. The research was finally published in 2021 in the Neuropsychologia Journal, the world's most prestigious journal in the scientific field of neuropsychology, a clinical discipline that converges neurology and psychology.

A total of 144 hearing people and 34 deaf people participated, of whom 24 had American Sign Language as their first language. All of them were subjected to the visualization of point-light displays of people performing athletic actions such as running, jumping rope or playing golf, among others. A point-light display is a motion capture of body movement, often used in film for digital special effects, a technique that has also been used extensively to research Sign Language, as in the following video:

Point-light display of a sentence in American Sign Language (CC BY-SA 4.0 by Athena.PEN via Wikimedia). A much smaller number of light points were used in the research of this article: only 18

In this research, each movement was captured from three perspectives (front view, oblique view and side view) which were represented with 18 point-light displays on the joints of the body, so there are far fewer light points than the video shown above for American Sign Language. The people participating in the study had to find out which athletic action they visualized on the screen with this information alone, i.e. by observing only the light points. Their perception was collected with questionnaires and electroencephalograms.

Participants visualized 18 light points (PLD) captured from human athletic movements from three angles and had to find out which movement was performed with this visualization alone. This image shows the action of jumping jacks (image: Quandt, Kubicek, Willis and Lamberton. 2021)

Confirmed Results

Deaf native Sign Language people showed less difficulty in perceiving movements than hearing people, even when those movements are not related to Sign Language, in this case, identifying athletic movements more quickly and with less effort. In the words of the researchers:

Taken together, the data suggests that deaf signers more readily process human biological motions, and that the visual changes already shown in certain aspects of motion perception for deaf signers also include faster and less effortful perception of human biological motions

The researchers believe that this reduced effort may be due to the lifelong experience of Deaf people in extracting and producing meaning through their own and other people's movements, even in harsh environments, when there is a lot of visual noise (a lot of movement in the same visualization).

The brains of hearing non-signers are processing human movements differently than deaf native sign language users

What Is This For?

In Unusualverse we already saw many years ago one of the applications of this benefit of sign language: in Oaxaca, a state in southern Mexico, several Deaf people were hired by the police to carry out video-surveillance work, monitoring up to 230 video cameras to detect crimes in the streets (you can read the article here).

This is one more benefit of sign languages that science has been proving over the last few years and that we have already published in Unusualverse:


  • Quandt, L. C., Kubicek, E., Willis, A., y Lamberton, J. (2021). Enhanced biological motion perception in deaf native signers. Neuropsychologia, 161, 107996.

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