I choose to look at the concept of perceptual organization. Specifically, the idea of convergence perspective and linear perspective. Depth perception gives us the ability to judge distances and there are two types of cues involved. One type is binocular cues which uses both eyes to judge distances and perspectives. Convergence cues is categorized as a binocular cue since it involves the use of both eyes. Another cue used in depth perception is monocular cues which uses one eye. Linear perspective is categorized under monocular cues. These two types of cues have the potential to be easily confused as they both involve focusing on a point of convergence. However, these two cues are vastly different.
As mentioned above convergence is a binocular cue. When you use the convergence depth cue both of your eyes move together to focus on an object that is in close proximity. The further the distance of the object the farther apart your eyes are. According to the Psychology textbook by Professor Wede convergence cues are used on objects that are within 50 feet of us. An example of convergence that you can do is to try to look at the tip of your nose. You will be able to feel both of your eyes focusing on your nose. If you want to be able to experience the gradual process of your eyes converging place one finger at an arms width and focus your eyes on it as you slowly bring it closer to your nose and you should be able to notice your eyes slowly converging.
Linear perspective is the process in which parallel lines will converge at a certain distance. Much like convergence linear perspective also relies on a point where objects merge or meet. However, linear perspective is monocular rather than binocular. There are three main parts to this type of cue and those are the vanishing point, which is where the lines converge, creating depth (Blumberg). The horizon line where the vanish point lies and orthogonal’s also known as parallel lines (Blumberg). Linear perspective is often used in artwork as it allows for depth to be created on flat surfaces. The closer the parallel lines are to each other, or the more they converge the more distance the audience will perceive.
I took a lot of art courses when I was in high school. There was always at least on assignment every year where I would have to draw a city scape or have some point on the horizon converge in order to create depth. At that point it was not explained why this helped to create depth. My teachers would merely explain how to do it and then leave us to do it by ourselves. I had never stopped to consider, how this trick worked to convince my mind that there was distance, or if one or both my eyes were engaged. Now however, I know from Psych 100 that linear perspective only uses one eye even though both eyes are looking at the picture or point. If you were to close one eye you would still perceive depth while with convergence the object would no longer be centered.
References
Amey, K. (2015). 17 miles, 93 bends and breathtaking views of the Douro Valley: The world’s best road is in Portugal’s wine region. The Daily Mail. Retrieved from www.dailymail.co.uk/travel/travel_news/article-3052472/The-world-s-best-road-voted-Portugal-s-wine-region.html
Bermann, J. (1960). Surprise Landing [Online Image]. Retrieved from https://norman.hrc.utexas.edu/NYJAdc/ItemDetails.cfm?id=601%23navtop
Blumberg, N. (2016) Linear Perspective. In Encyclopaedia Britannica online. Retrieved from www.britannica.com/art/linear-perspective