Hemiretinal differences in the effect of a rotating visual background on the subjective visual vertical.

Sixteen normal subjects were tested for their accuracy in judging the verticality of a visual edge before or during exposure to a moving visual background. All subjects showed a counter-rotation of the subjective visual vertical as a consequence of movement of the visual background. The effect was stronger for binocular than monocular viewing and for nasal than temporal hemiretina stimulation. No hemispheric asymmetries were observed. These results show a predominance of the crossed visual pathways originating from the nasal hemiretinae in a visual effect presumably involving a visual-vestibular interaction.