When spots are presented successively, apparent motions is perceived. Computationally, motion competition in apparent motion is an ill-posed problem and to reveal the underlying mechanisms is an important issue not only in cognitive science but also in computer vision. Our previous studies [1,2] revealed how the spatial and temporal factors counterbalance in motion competition and found that the counterbalancing relation was modulated by the directional condition between the competing motions, that is, whether the two motions were directed to the same or opposite direction. However, it was not clear which caused this effect, the directional difference of the motions or laterality, namely the difference between bi-hemispheric and mono-hemispheric motion processes. Here we show that this directional modulation is originated from laterality. This fact suggests that cortico-cortical interaction is responsible for spatiotemporal integration for perception of moving objects in complex environments.