Objectives
Students tend to think that images come into the brain fully formed, like a photograph, and that the brain simply receives the image, similar to the way a camera captures an image. To be honest, while I had not given it much thought, this is more or less what I thought as well. But this is not the way it happens. What does happen is an amazing, complicated process. And this is what I'd like to explore with my students, i.e. the basic process of vision, how light enters our retina and then how that information is processed by our brain.
The visual system is part of the central nervous system. It is able to take light that enters through the retina and interpret those signals into a representation of the surrounding world. These signals are sent from the eye along the optical nerve to the visual cortex, which is located in the back of the head above the cerebellum. The primary visual cortex is located in the occipital lobe and is the processing center of vision. There is a widely accepted, but still controversial, theory of how vision is processed. Neuroscience is not in agreement as to how segregated the two systems are or how important the segregation is in our visual processing. This explanation of the two systems is probably oversimplified. Despite these potential limitations, I will focus on this theory with my students in my unit. I believe the students will be able to understand the explanation and begin to think about art through this theory.
The theory of visual processing purports that as signals leave the occipital lobe, they follow two main channels or "streams". In the occipital lobe, the brain specializes visual information into two distinct pathways: the dorsal stream and the ventral stream (Figure 1). Both streams emerge from the primary visual cortex, in the occipital lobe. The dorsal stream leaves the primary visual cortex and moves to the parietal lobe. The dorsal stream is commonly referred to the "where" system because it is used for processing spatial locations, guidance of actions, such as reaching, and recognizing where objects are in space. It is also known as the parietal stream. The ventral stream leaves the primary
visual cortex, terminating in the temporal lobe. The ventral stream is called the "what" system because it is used for object and form recognition. It has a strong connection to the medial temporal lobe. The medial temporal lobe stores long—term memories. This connection obviously helps with object and face recognition.
I teach in an inner—city middle school, which houses the district's International Baccalaureate Program. The IB program functions as a school within a school and serves gifted students from throughout the school system. Half of my classes are regular classes and half are IB classes. The IB students can select either visual art or a music class; this elective is a yearlong course. I have a block schedule with 90—minute classes; therefore, the students go to art every other day for an hour and a half.
This unit is being created for my 7 th grade classes. I want my students to develop a basic understanding of how vision works: how light is turned into information that is then processed by the brain and how the brain uses different systems to interpret that information. I want them to understand the rules and assumptions that the brain makes and how they effect our perception of the visual world. I also wish for the students to understand the basic workings of the brain and how these rules actually impact art and how we see it. The visual pathways can in fact play games with our perceptions, creating optical illusions.
There will be three main objectives. The students will create three studio projects: one focusing on depth, one on color, and one on the illusion of movement. Although I introduce perspective and illusions of depth techniques in 6 th grade, I plan on revisiting them in this unit. Through the lens of how the brain is involved, we will revisit illusions of depth, focusing on illusions of depth in optical illusions. I will focus on color and will definitely cover the complimentary colors. It would be logical to cover complimentary colors, with afterimages, in this unit. In 7 th grade, there is a state objective on creating illusions of movement. Creating an illusion of movement in a work of art can be approached in a variety of ways, but one of the optical illusions that I plan on highlighting will be illusions of movement. I will focus both on how the brain makes this happen and how students can create an artwork using these principles.
There are three main concepts that I want my students to explore and ultimately understand by the time they finish this unit. First, I want them to understand that seeing (or vision) is not simply the transmission of an image, but is information processing. I want them to understand how the basic vision process works and the two systems of vision. Finally, I want them to understand how artists have, through observation and experimentation, "discovered how to create visual effects that take advantage of how the visual system works". 1
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