Nesting of Focal Within Peripheral Vision Promotes Interactions Across Nested Time Scales in Head Sway: Multifractal Evidence From Accelerometry During Manual and Walking-Based Fitts Tasks

Nesting is a major cornerstone in ecological theorizing about visual perception, through both nesting of surface layout in locomotory movements and nesting of visually available surfaces within each other, from focal to peripheral vision. This work sought to probe these nesting relationships by examining the effects of the visual periphery on the strength of interactions among nested time scales in head sway. That is, we tested whether spatial nesting of the focal within peripheral visual fields stimulated nonlinear interactions amid temporal nesting. We examined head sway during 2 variants of the Fitts task, one involving manual pointing by seated participants and another involving walking comfortably with upright standing posture. All participants completed both tasks but were randomly assigned to experience these tasks with or without the visual periphery available. Multifractal analysis of head sway revealed that visual availability of the periphery promoted nonlinear interactions across nested time scales, but this effect depended on how much head sway extended across a plane than more ballistically along a single axis of variability.