Figure 4. Head Position.

Median head positions while walking on the balcony in the horizontal (yaw) and vertical planes (pitch) for susceptibles (red) and controls (blue), pooled for all four walking conditions. Abscissa indicates deviations of horizontal head position from balcony midline in degrees (0° reference); ordinate indicates deviations of vertical head position from earth horizontal in degrees (0°). Depicted are the group mean interquartile ranges (bars), centered at the mean group median head positions in both planes (crossing). Horizontal head positions for the walk back conditions are mirrored so that all positive values reflect head positions toward the open side opposite the wall (depth), and negative values represent head orientations toward the wall side. For the vertical plane, positive values indicate head extension, negative head flexion. Susceptibles direct their head less toward the open side (yaw median: p = .062), and restrict it to a smaller area (yaw range: p = .013; pitch range: p = .034).