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Abstract

Most of the previous studies of spatial cognition have concerned two-dimensional navigation and little is known regarding the problem of three-dimensional (3D) spatial memory. We studied the memorisation of complex 3D-structured environments after exploring them. In the terrestrial condition, self-motion included yaw rotations and vertical translations facing the walls, whereas in the weightless condition subjects could move along or turn about any axis. We found previously that when only sideways (yaw) mental rotations had to be performed in order to shift from the experienced egocentric to the tested allocentric reference frame, memorisation was improved. In the present investigation we tilted both self-motion visual and gravity reference frames relative to the body during a natural displacement. We examined whether having any single rotation axis was enough to facilitate this reference shift or, if not, what aspect of the terrestrial condition – where visual displacement rotation, gravity and body axes were aligned – led to better performance. Field dependent (FD) and independent (FI) subjects, as determined by the rod and frame test, showed distinct effects of the navigation conditions. The FD group performance was markedly impaired when gravity and body axis were in conflict, whereas FI performance only slightly worsened when the body was tilted and the rotation axis remained aligned with gravity.