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.