Effects of type of visual information on characteristics of standing sway

Effects of Type of Visual Information on Characteristics of Standing Sway May, 1983 Ann-Patrice Hickey, B.S.M.E., Clarkson College .3. .Clarkson College, Ph.D., University of Massachusetts Directed by: Dr. Ernest Dzendolet A series of experiments were conducted to investigate the effects of various types of visual information on a subjects lateral sway, as measured by a sway platform and analysed via a Power Spectral Density (PSD) analysis. The subjects were 56 normal young adult subjects, 28 women and 28 men. In the first three of the four experiments conducted, an unusual visual condition; blindfold with eyes open, ganzfeld, or a helmet with an attached visual scene, was compared with a visual condition in which the stimuli were those of the lab room. In the fourth experiment, the helmet with the attached visual scene was compared with another helmet matched for weight and torque loading on the neck but without an attached visual scene. For each experiment two ANOVA's were performed, each over a different frequency range. Each ANOVA utilized a one between-subject variable (gender) and two within-subject variable (condition and frequency), repeated measurement design. Several sign tests were also performed on the data to tease out consistent if small differences between conditions. In addition, the subjects data were pooled by gender and condition and these average records were plotted with PSD vs frequency on a semilog scale. The plots could be fit by four linear segnents. Results suggest that subjects sway less in the ganzfeld condition than in the environmental condition. Gender differences were found in the blindfold vs lab environment experiment and the helmet with the visual scene vs the control helmet experiment but not in the other comparisons, suggesting that gender differences may be either unstable or condition dependent. Results are discussed and a chapter on directions for future research is included.