Real-time visual feedback about postural activity increases postural instability and visually induced motion sickness

Background: Several studies have shown that the kinematics of standing body sway can be influenced by the provision of real time feedback about postural activity through visual displays. Research question: We asked whether real time visual feedback about the position of the body's center of pressure (COP) might affect body sway and the occurrence of visually induced motion sickness. Methods: Standing participants (women) were exposed to complex visual oscillation in a moving room, a device that nearly filled the field of view. During exposure to complex visual oscillations, we provided real time feedback about displacements of the body's center of pressure through a visual display presented on a tablet computer. Results: The incidence of motion sickness was greater than in a closely related study that did not provide real time feedback. We monitored the kinematics of the body's center of pressure before and during exposure to visual motion stimuli. Body sway differed between participants who reported motion sickness and those who did not. These differences existed before any participants experienced subjective symptoms of motion sickness. Significance: Real time visual feedback about COP displacement did not reduce visually induced motion sickness, and may have increased it. We identified postural precursors of motion sickness that may have been exacerbated by the COP display. The results indicate that visual feedback about postural activity can destabilize postural control, leading to negative side effects. We suggest possible alternative types of visual displays that might help to stabilize posture, and reduce motion sickness.