A New Dynamic Virtual Stimulation Protocol to Induce Vection

Abstract

The dynamic visual stimulation (DS) protocol was employed for inducing vection during stabilometric test (orthostatic position in a force platform). The center of pressure (COP) displacement signals of 29 healthy volunteers were acquired with subject observing a virtual scene (1.72 × 1.16 m) projected 1 m ahead of the force platform and centered at the vision line (visual angle: θl = 81.4° and θv = 60.2°). This scene consists of a room containing a floor with chessboard pattern, walls and ceiling with distinct texture and furniture. To induce vection, the virtual scenario (floor, walls and ceiling) moved in a forward direction (or backward), during 250 ms (constant velocity: Vi = 2 m/s), so that the furniture was expanded (or reduced). For each DS scene, the luminance changed 2 cd/m² with optic flow stimulation as a tunnel pattern. A set of 100 DS distracter stimuli was applied in a random order, interspersed by 10 s of Static Scene and synchronized by the start of exhibiting scene. The percentage of DS inducing vection differs among volunteers, varying from 63% to 80%, hence indicating the potential applications of this DS protocol in postural control study.