Depth Perception is the ability to judge distances. Our eyes have certain ways of focusing that allow us to decide when things are closer or farther away from us. Within the overarching concept of depth perception there are two types of cues: monocular and binocular cues. Monocular cues require one eye, and can determine a variety of things, such as relative size, Interposition, aerial perspective, linear perspective, texture gradient, and motion parallax. Relative size is where the object that casts a smaller retinal image is further away. Interposition is where one object blocks another, and the one blocking the other is closer. Aerial perspective shows that the hazier the part of the image is, the further it is away. Linear perspective is where parallel lines converge with distance. Texture gradient is where the further away an object is, the less detailed it is. Lastly, motion parallax is where closer objects appear to go faster than further objects. All of these cues only employ the use of one eye, as opposed to binocular cues, which use both eyes. Binocular cues include retinal disparity and convergence. Retinal disparity is how we combine the two images from separate eyes and make a 3D picture. This is why it seems that we view a cohesive plane rather than two different perspectives. Convergence is how our eyes move together to view close objects, and further apart to view distant objects. The experience I am going to tell has to do with convergence.
As I said above, convergence is our ability to focus on something close or far away from us. This has been a bit of a struggle for me, as my right eye is slightly lazy. When I focus on an object, such as a pen, close to me and move it closer, eventually my right eye gives up and goes back to a neutral forward position. Because of this, I was given an exercise of sorts from my doctor in order to work on my focusing. I was given a string, with 3 large colored beads. Each were a different color: red, yellow, and green. The point was to hold the string up in front of my eyes, so the colored beads were going away from me. Each was a different distance apart, and I would switch from color to color to practice focusing on each. This exercise showed the ability of convergence, as my eyes had to move closer together to focus on the closest bead, and further away to focus on the further bead. Both of my eyes had to work together to focus on each bead, and it helped to strengthen the abilities of my right eye so I keep this ability.