Depth perception is broken up into two different types of cues, monocular and binocular. Monocular only requires one eye where binocular requires both eyes. By definition, “binocular depth cues are depth cues that are created by retinal image disparity—that is, the space between our eyes, and thus which require the coordination of both eyes” (Wede). On each eye, there is a different image that is recognized. The images are combined into one encompassing image in the visual cortex. The overlaying of two images causes us to see depth.
Three-dimensional glasses in conjunction with specifically made three-dimensional movies allow retinal image disparity to be manipulated. The three-dimensional glasses are different colors and the lenses are different to force the wearer to see two different images. In my experience, I went to see a three-dimensional movie. Being the curious kid that I was, I would take the glasses off, keep one eye in the glasses, switch eyes, and then would wear the glasses correctly. The movie had the three-dimensional aspects outlined in blue and red. My glasses were blue and red and therefore each lens picked up the respective color and formed two images. With only one eye looking through the lens, I could not see the three-dimensional effects.
Another example of retinal disparity has to do with Magic Eye pictures. A person can only see the hidden image in a Magic Eye picture by adjusting the focus of their eyes either in front of the picture, or behind it. As with the three-dimensional glasses, the small distance between a person’s eyes and the different images perceived on each eye, allow a person to see the hidden image. On the bus in 9th grade, a girl used to sit next to me on the bus. One day she showed me her Magic Eye book that she had gotten as a gift. She explained to me that I had to look through the book in order to see the image. I spent the next week repeatedly trying to see the image and failing. Finally, I saw the image. I held my figure out and then slowly moved the book in between my eyes and my finger. I was so excited when I finally figured out how to manipulate my eyes so that I could see the image. I can now find the image in almost every Magic Eye I see. Also, because I learned how to do this, I can now dilate and contact my pupils on demand by changing my depth of focus. Because of retinal image disparity and depth perception, I now understand the psychological and scientific reason as to why I can see the image.
Works Cited
Wede, Josh. Introductory Psychology. Pressbooks. Retrieved from https://psu.pb.unizin.org/intropsych/chapter/chapter-4-sensation-perception-vision/#43