Does the world rock when the eyes roll? Allocentric orientation representation, ocular counterroll, and the subjective visual vertical

Examined this inter-relation between ocular counterroll (OCR) and perceived visual orientation in 2 experiment. The latter was assessed via the subjective visual vertical, subjective visual vertical (SVV), which is determined when a S judges the orientation of an indicator (e.g., a short line segment) as apparently vertical. The OCR was measured by using a video-oculographic system. In Exp 1, a human centrifuge was used to test the effect of an increase of the gravito-inertial force (GIF) on SVV and OCR using 4 Ss. Exp 2 was inspired by the fact that OCR can also be elicited during "barbecue rotation". Again, it was the aim to compare OCR and SVV in different body positions, such as pure roll and barbecue rotated tilts using 4 new Ss. The results indicate that increasing the GIF in Exp 1 had a divergent effect on SVV and OCR: the gain of OCR increases whereas the SVV changed differently, at obtuse tilt angles even in the opposite direction. OCR and SVV were again found to dissociate in Exp 2, which emphasizes the fact that the SVV and OCR are not controlled by the same neural mechanism, but rather use different spatial reference information.