V FOR = mean error with only visual FOR disrupted (F±18 and CM0), E FOR = mean error with only egocentric FOR disrupted (WF and CM±9), VE FOR obs = mean error observed with visual and egocentric FOR disrupted (F±18 and CM±9), VE FOR MLE = mean error with visual and egocentric FOR disrupted calculated with MLE, VE FOR WTA = mean error with visual and egocentric FOR disrupted calculated with WTA, VE FOR UWM = mean error with visual and egocentric FOR disrupted calculated with unweighted mean error, F−18 = Frame tilted at 18° to the left, WF = cylinder-shape optical tunnel, F+18 = Frame tilted at 18° to the right, CM−9 = deviation of the head centre of mass at 9° to the left, CM0 = no deviation of the head centre of mass, CM+9 = deviation of the head centre of mass at 9° to the right.