title: Effects of Real-World Versus Virtual Environments on Joint Excursions in Full-Body Reaching Tasks.
abstract: Starting from an upright standing posture and reaching for a target that requires some forward bending of the trunk can involve many different configurations of the trunk and limb segments. We sought to determine if configurations of the limb and trunk segments during our standardized full-body reaching tasks were influenced by the visual environment. This paper examined movement patterns of healthy participants ([Formula: see text], eight female and nine male) performing full body reaching tasks to: 1) real-world targets; 2) virtual targets presented on a 3-D television; and 3) virtual targets presented using a head-mounted display. For reaches performed in the virtual world, the avatar was presented from a third-person perspective for the 3-D television and from a first-person perspective for the head-mounted display. Reaches to virtual targets resulted in significantly greater excursions of the ankle, knee, hip, spine, and shoulder compared with reaches made to real-world targets. This resulted in significant differences in the forward and downward displacements of the whole-body center of mass between the visual environments. Visual environment clearly influences how subjects perform full-body reaching tasks to static targets. Because a primary goal of virtual reality within rehabilitation is often to restore movement following orthopedic or neurologic injury, it is important to understand how visual environment will affect motor behavior. The present findings suggest that the existing game systems that track and present avatars from a third-person perspective elicit significantly different motor behavior when compared with the same tasks being presented from a first-person perspective.
authors.affiliation: School of Rehabilitation and Communication Sciences Ohio University Athens OH 45701 USA.
authors.forename: James S
authors.initials: JS
authors.lastname: Thomas
authors.affiliation: Department of Psychology Ohio University Athens OH 45701 USA.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: France
authors.affiliation: Department of Mechanical Engineering Ohio University Athens OH 45701 USA.
authors.forename: Samuel T
authors.initials: ST
authors.lastname: Leitkam
authors.affiliation: School of Rehabilitation and Communication Sciences Ohio University Athens OH 45701 USA.
authors.forename: Megan E
authors.initials: ME
authors.lastname: Applegate
authors.affiliation: Department of Bioengineering Virginia Commonwealth University Richmond VA 23284 USA.
authors.forename: Peter E
authors.initials: PE
authors.lastname: Pidcoe
authors.affiliation: Department of Osteopathic Manipulative Medicine Ohio University-Heritage College of Osteopathic Medicine Athens OH 45701 USA.
authors.forename: Stevan
authors.initials: S
authors.lastname: Walkowski
keywords: Full-body reaching; kinematics; trunk control; virtual reality