Perception of the visual horizontal during lateral body tilt: right-left asymmetries.

Subjects, 55 males and 45 females, indicated by means of a luminescent rod the visual horizontal under conditions of lateral body tilt ranging from 10 degrees to 90 degrees to the right and to the left. There was a non-linear effect of the angle of tilt on the degree of deviation of apparent from objective horizontal. With small angles of tilt the apparent horizontal tended to deviate opposite to the direction of body tilt, with larger angles, in the direction of tilt. Uncertainty of judgment increased with increasing angles of tilt.