In some primates, there is only a bar of bone on the lateral side of the eye. This is called a post-orbital bar. In other primates, the whole side and back of the eye is protected by bone, thus they have a post-orbital wall. Since the main sense used by primates is vision, the physical features related to smell are reduced in size. Primates have a reduced snout and the area of the brain related to smell is much larger than that area in a dog.
Primates use vision and touch to explore their environment.