When visual circles become acoustic ellipses: sounds evoking accelerations modify visuo-motor coupling with biological motions

  • Thoret Etienne
  • Aramaki Mitsuko
  • Bringoux Lionel
  • Kronland-Martinet Richard
  • Ystad Sølvi


Biological motions have a very notable visual processing. When a spotlight is moving on a circle without complying with the 1/3 power law, with accelerations on two opposite parts for instance, it is perceived elliptical (Viviani, 1989). Furthermore, when complying with this law, the motion of a spotlight is perceived uniform while visual accelerations are perceived in the curved parts of a trajectory when it moves at constant velocity (Viviani, 1992). From the auditory point of view, a recent study revealed that the timbre variations of the friction sounds produced when someone is drawing contained enough information to enable the recognition of the 1/3 power law, and moreover to discriminate geometrical shapes to a certain extent (Thoret, 2014). In this study, we investigate the audiovisual integration of biological motions and in particular whether friction sounds can modulate visuo-motor coupling with such motions. In a first experiment based on a Viviani’s protocol (Viviani, 1997), the visuo-motor coupling is investigated in visual open loop and confirmed perceptual motor interactions. A second experiment revealed that auditory perception of sound evoking motions can strongly biased visuo-motor reproduction of a moving spotlight in its geometrical and dynamical properties. These experiments showed that auditory completely shapes visuo-motor coupling. And above all, they evidenced the role of auditory and motor planning in the multisensory integration of motion in a new original fashion opening many theoretical and applicative perspectives.