(A)–(C) real motion (tilt), (D)–(F) corresponding erroneous translation. (A) During OVAR, the head rotates around a tilted axis (left). In an egocentric frame of reference, the gravity vector rotates around the head (right). (B) During OVAR, the head passes though the Left-Ear-Down (LED), Nose-Down (ND), Right-Ear-Down (RED) and Nose-Up (NU) orientations successively. (C) Pitch and roll oscillations corresponding to the head trajectory in B. (D) Forward-backward (FB) and leftward-rightward (LR) oscillations generating the same otolith activation as in C. (E) Erroneous translational acceleration corresponding to the head orientations represented in B. (F) Illusion of translation along a circular trajectory during steady-state OVAR in humans, obtained by following the pattern of acceleration illusions in E (Vingerhoets et al. 2006; 2007).