Vection aftereffects from expanding/contracting stimuli.

We presented three types of visual stimuli (blank, static and dynamic random dots) following optic flow stimuli and measured the durations of the motion aftereffects (MAEs) and aftereffects of vection (vection aftereffects, VAEs). The VAEs were induced in the direction opposite to the MAEs. However, the VAEs were not the same as the vection induced by the MAEs because the VAEs were sustained even after the MAEs vanished. In addition, when vection was facilitated or inhibited by the static dot plane in front or in the back of the optic flow, only the VAE strength was modulated, while the MAE was constant between the two conditions. From these results, we conclude that the vection-inducing mechanism shares some neural units with the motion processing mechanisms but has an additional aspect that adapts independently of the motion processing mechanisms.