The synchronization hypothesis is the likely idea for the binding problem in the brain. Here we tested whether the theory is applicable for the occurrence of either binocular fusion or binocular rivalry. We first showed patterns of activated patches in V1 with proceeding from fusion to rivalry on the basis of Hubel and Wiesel's 1979 illustration. We then assumed that the strength of synchrony between the patches in the left-eye and right-eye ocular dominance columns is a crucial determinant for the divergence between fusion and rivalry. By using the strength of fusion between the paired images as a measure of degree of synchrony, we confirm the assumption about interocular vision and the synchronization hypothesis as well.