The contribution of different parts of the visual field to the perception of upright

We determined the relative effectiveness of different areas of the visual field in determining the perceptual upright. The perceptual upright was measured using the character ‘p’, the identity of which depended on its perceived orientation (the Oriented Character Recognition Test). The visual field was divided into left and right, upper and lower, and central and peripheral halves, with different backgrounds presented in each area. The left and right visual fields contributed equally to the perceptual upright while the lower visual field demonstrated a larger effect on the perceptual upright as compared to the upper visual field. The central and peripheral visual fields interacted with one another in a complex manner, although a separate experiment suggested that the peripheral visual field did not alter the perceived orientation of the central field.

► An increase in stimulus area results in an increase in effectiveness in providing cues to the perceptual upright.
► The left and right visual fields are symmetric when assisting the brain in determining the direction of up.
► The lower visual field is of greater importance as compared to the upper visual field in determining the direction of up.
► There is a complex interaction taking place between central and peripheral fields in determining the direction of up.