Internal reference frames for representation and storage of visual information: The role of gravity

The influence of gravity on the representation and storage of visual orientation information was analyzed using the oblique effect. A psychophysical task was performed by the subjects in which a visually-presented stimulus line was aligned with the remembered orientation of a reference stimulus line presented moments earlier. Experiments were carried out on 5 cosmonauts during orbital space flight and on 13 subjects in normal gravity conditions with a tilting chair. On earth, a distinct preference for horizontally and vertically oriented stimuli was found when the body and gravitational axes were aligned, but in microgravity conditions, preference for vertical and horizontal axes was maintained.