Head contribution to gaze shifts of varying eccentricity (x-axis).

Each symbol shows the mean head contribution to a gaze shift—the percentage of the gaze shift accomplished through head rotation as opposed to eye rotation. Symbols above the black horizontal line at 50% indicate that the head contributed more than the eyes; symbols below 50% indicate that the eyes contributed more to the gaze shift compared to the head. Orange symbols represent the walking task and blue symbols represent the search and retrieval task. Error bars (within the symbols) indicate ± 1 standard error. Three top-down drawings of an observer depict the eye contribution (gray shading) versus head contribution (green shading) for gaze shifts at 40º in the search task, 60º in the walking task, and 70º in the search task.