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Visuomotor Interactions and Perceptual Judgments in Virtual Reality Simulating Different Levels of Gravity

Visuomotor Interactions and Perceptual Judgments in Virtual Reality Simulating Different Levels of Gravity

Authors :
Barbara La Scaleia
Francesca Ceccarelli
Francesco Lacquaniti
Myrka Zago
Source :
Frontiers in Bioengineering and Biotechnology, Vol 8 (2020)
Publication Year :
2020
Publisher :
Frontiers Media S.A., 2020.

Abstract

Virtual reality is used to manipulate sensorimotor interactions in a controlled manner. A critical issue is represented by the extent to which virtual scenarios must conform to physical realism to allow ecological human–machine interactions. Among the physical constraints, Earth gravity is one of the most pervasive and significant for sensorimotor coordination. However, it is still unclear whether visual perception is sensitive to the level of gravity acting on target motion displayed in virtual reality, given the poor visual discrimination of accelerations. To test gravity sensitivity, we asked participants to hit a virtual ball rolling down an incline and falling in air, and to report whether ball motion was perceived as natural or unnatural. We manipulated the gravity level independently for the motion on the incline and for the motion in air. The ball was always visible during rolling, whereas it was visible or occluded during falling before interception. The scene included several cues allowing metric calibration of visual space and motion. We found that the perception rate of natural motion was significantly higher and less variable when ball kinematics was congruent with Earth gravity during both rolling and falling. Moreover, the timing of target interception was accurate only in this condition. Neither naturalness perception nor interception timing depended significantly on whether the target was visible during free-fall. Even when occluded, free-fall under natural gravity was correctly extrapolated from the preceding, visible phase of rolling motion. Naturalness perception depended on motor performance, in addition to the gravity level. In sum, both motor and perceptual responses were guided by an internal model of Earth gravity effects. We suggest that, in order to enhance perceptual sensitivity to physical realism, virtual reality should involve visual backgrounds with metric cues and closed-loop sensorimotor interactions. This suggestion might be especially relevant for the design of rehabilitation protocols.

Details

Language :
English
ISSN :
22964185
Volume :
8
Database :
Directory of Open Access Journals
Journal :
Frontiers in Bioengineering and Biotechnology
Publication Type :
Academic Journal
Accession number :
edsdoj.490472c1ac4e4c16a9612d09348fb42c
Document Type :
article
Full Text :
https://doi.org/10.3389/fbioe.2020.00076