Postural control: visual and cognitive manipulations.

Numerous questions exist regarding the utilization of sensory information for postural control. Past research has established the possibility that cognitive tasks requiring visual perception may affect the processing of visual information used for postural control. The purpose of this study was two fold: (1) to investigate the effects of varying demands of visual perception and (2) to evaluate the effects of performing a cognitive task on postural control in healthy, young adults (N=30). Three posture-related dependent variables were recorded during the manipulation of two independent variables (eye movement and modality of presentation of a cognitive task). The two levels of eye movement were movement and no movement, while the three levels of modality of presentation were visual, auditory, and none. A 2x3 repeated measures ANOVA was applied to the data to investigate the presence of group differences. Significantly more variability was observed in the no cognitive condition than the visual and the auditory for medial-lateral (M--L) COP variability. Additionally, the eye movement condition revealed significantly greater M--L COP variability than the no eye movement condition. No differences were observed between the visual and auditory conditions for any dependent variable. Therefore, the greatest COP variability was observed in the eye movement and no cognitive condition. Further, an interesting relationship between the measures of COP variability and sway velocity was described.