Abstract
<p>How does the visual system read orientation from an extended scene to keep the perception of space stablerelative to the body? We separated two orientations that are normally confounded — the global orientationof a long array of parallel lines and the local orientation of the lines composing it — and measured theirinfluence on two egocentric norms: visually perceived eye level (VPEL) and visually perceived vertical(VPV). Across eight experiments the global orientation of the array set both norms, whereas the localorientation of the lines was negligible in a long array (Study 1) and re-emerged only when the array wasshortened and the lines lengthened (Study 2). Array length strengthened the influence of array orientation,and line length shifted the balance toward line orientation, so the two orientations appear to trade off withtheir relative extent rather than simply add. This pattern implies that egocentric space is stabilized byorientation read at two scales — a large-scale second-order channel and a local first-order channel —combined according to their spatial extent across the visual periphery.</p>