The Influence of Different Visual Stimuli and Head Movement on the Control of Postural Sway

Visual, proprioceptive and vestibular systems clearly contribute to postural control, as several studies have shown that visual [1] proprioceptive [2] or vestibular [3] stimulation evokes and controls body sway. Each sensory system detects an “error”, indicating a deviation in the body’s orientation from a reference position. The visual system is considered to be the most complex [4] of the sensory systems and has a central importance [5]. Its operation involves structures and mechanisms for obtaining information, which are obtained through the refraction of light from the surfaces of objects, plants, animals, etc. Visual conflicts can have powerful effects on balance. Visual movements in the environment can cause postural changes and imbalance, as well as motion sickness in healthy adults [5]. According to Ehrenfried [7] a problem with the results of many studies in this area has been the variability and the apparent inconsistency in responses. A hypothesis exists that there may be a functional relationship between body sway and visually guided eye movements. This is because the accuracy of such movements can be influenced by small changes in body sway. On the other hand, eye movements that are not visually guided are not subject to being facilitated or interrupted by small changes in body sway [8].