Stepping in Place While Voluntarily Turning Around Produces a Long-Lasting Posteffect Consisting in Inadvertent Turning While Stepping Eyes Closed

Figure 4

Head angular acceleration. (a) to (h) show the head movements in the horizontal plane during the podokinetic stimulation (Pod Stim, (a)), PKAR (c), voluntary turning (Vol Turn, (e)), and vPKAR (g). The two dots in (a), (c), (e), and (g) indicate the initial positions of the markers placed on the right (black dot) and left (grey dot) side of the head. Head velocity (solid line) and acceleration (dashed line) are reported in (b), (d), (f), and (h). The rotational effect of voluntary turning can be seen by the bias in the angular velocity profile (f). (i) and (j) show the mean values of head velocity (i) and acceleration (j) across subjects. Head showed angular acceleration (j) under both voluntary turning and podokinetic stimulation. There were no differences between the two posteffects for either head velocity or acceleration. indicates significant difference () between mean head velocities (i) and accelerations (j).