Are You Seeing What I'm Seeing?
Explaining Light, Color, and Perception Using Illusions and Art in a Middle School CurriculumKeith Gaudet
Introduction
Art has been around for as long as people have been wandering the earth. Art takes in many forms drawing, painting, sculpture, architecture, music, literature, drama, dance, languages, history, and philosophy. Since art is so vast in content and intertwined with humanity, it would only be logical to combine it with any of the core subject areas (math, science, language arts, and social studies). Since I teach math and science, I will focus on how one can integrate math and science with art. One unit that is focused on in seventh grade is light and color. Since this is such a visual concept, I wanted to think of ways to show how artists use their knowledge of light and color in their work. I thought illusions in art would be a good way of talking about the concepts of light and color; thus the topic of this curriculum will be how to explain perception using illusions and art in a classroom.
I have long been fascinated with magic and illusions. I used to dream that one day I would be the next David Copperfield. I attempted to teach myself some simple magic tricks and performed them in front of my family and friends. It was no simple task, so I lost interest in performing. I simply could not do the tricks and illusions well enough to dazzle one's eye. Now, years later with my magic books collecting dust, I find myself teaching 7th graders physical science and the science behind why illusions work. This past year I did a small segment on optical illusions during my light, color and sound unit. The students had fun with the illusions I put up on the overhead projector but I felt like I needed something more for my students to do. By writing this curriculum, I am hoping that I will find more interactive ways my students can understand perception and see how illusions are very much a part of science.
The target audience for this curriculum is 7th grade math and physical science students. This unit can be taught as a thematic unit. The science topic being stressed is light and color and can be integrated with math skills such as pattern recognition. Educators can adapt these lessons for use across all core subject areas. Though this unit will focus on the middle school levels, high school teachers can modify this with Physics, Biology, American and World History courses. I have also designed the lesson plans so that they will meet the needs of LEP (Limited English Proficient), bilingual, and special education students. I have set up this paper in four major sections: Introduction to the Curriculum, The Host School Academic Setting, Scientific Background, and Implementation of Unit.
Academic Setting
Truman Middle School, located at 9400 Benavides Rd. SW, is one of 25 middle schools that make up the Albuquerque Public Schools district. It is one of three middle schools that serve the West Mesa Cluster (John Adams and Jimmy Carter being the other two). Truman’s enrollment was roughly 650 students during the 2000-2001 school year. Hispanics make up more than three quarters (80%) of the total student population. For all APS middle schools, Hispanics make up 48% of all student population. The rest of Truman’s ethnic profile is as follows: Anglo (11%), Black and Indian (4%), Asian (.5%) and "other" backgrounds (.4%).
Historically, many Truman Middle School’ students receive free or reduced cost meals that are provided by APS Food Services. To qualify for free meals in the 1998-1999 school year, a family of four would have had to earn less than $21,385.
To qualify for the reduced cost meals, a family would have had to earn between $21,386 and $30,433. The mean of Truman community’s income was $28,641. Over 3/4 of the students receive meal services. The district average for a middle schools is less than half of the students.
Truman Middle School has a fairly young staff. The percentages of teachers with zero to five years and six to ten years of experience are both 33.3%. The APS middle school average percentages are 27.1% and 23.7%, respectively. Only 7.2% of Truman’s staff has 11-15 years of experience. The middle school average is double that of Truman’s: 14.7%. There is also a big disparity between teachers with more than 15 years experience at Truman and the rest of APS, 26% and 34.5% respectively. Nearly two-thirds of the staff have Bachelor’s degrees. Percentages are roughly the same when comparing the number of male to female teachers at Truman. (All data is taken from the 1998-1999 APS School Research, Development and Accountability Division).
The school’s mission statement is simple and straightforward: "Truman Middle School is a community of learners dedicated to developing Quality, Character, and Competency for success in the 21st century." Truman has a very large number of support programs and activities aimed at students as well the staff and community. Such programs include a school-wide bilingual program, special education, Title I School Wide Literacy Program, intramural sports, and the Middle School Cluster Initiative Activities.
Scientific Background
According to the Merriam-Webster's Online Collegiate Dictionary, an illusion is (1) a misleading image presented to the vision; (2) something that deceives or misleads intellectually; (3) perception of something objectively existing in such a way as to cause misinterpretation of its actual nature. The word is derived from a Latin word which means to mock. There is one key word in this definition that needs to be understood before working with and viewing illusions: vision. One must understand how the human eye and brain work. The eye works very much like a camera. (Figure 1 below is a diagram of the human eye).
The eye is not receiving a direct image of an object, but rather the eye is receiving light. Light enters the eye through the cornea. The cornea is a soft, transparent film that bends the rays of light before they reach the next stage in the eye, the pupil. The pupil, which looks like a black circle when one looks in a mirror, is actually a small opening in the iris. The pupil is what limits the amount of light that enters the eye. Because the iris is a muscle, it has the ablility to expand and contract around the pupil, thus regulating the light entering the eye. After passing through the pupil, the light rays go through the lens and bend towards the retina, which forms the back of the eye. In the same manner that the iris supports the pupil, muscles support the lens. These muscles control the shape of the lens. When a person is using a camera, their lens turns in a certain direction to focus on distant objects, and in the opposite direction for closer objects. If the eye looks at something far away, the lens muscles are relaxed. The muscles contract and make the lens fatter in the middle when observing an object close up. The retina is the "centerpiece" of the eye. It is one of the most delicate and sensitive parts of the human body. The retina would be considered the "film" of the camera. As light is being spread out onto the retina, an image forms of what a person trying to see. However, the image on the retina is upside down and will be reversed from left to right (Figure 2 shows this example). Attached to the retina are millions of nerve fibers, each of which is connected to certain parts of the brain. These nerve fibers transmit electrical impulses to the brain for processing. This collection of pulses is a sort of code that our brain interprets. These fibers are grouped into one big cable called the optic nerve. This could be considered the stairway to the brain. The image is sent through the optic nerve as electrical impulses to the visual cortex (the back part of the brain that processes visual images). Not all images can be seen. We have what is called a "blind spot." This is a small section of the eye near the optic nerve. Here this spot is not susceptible to light, and has photoreceptors. (Figure 3 is a classic demonstration to show that one does have a blind spot: Look at the "X" with your left eye closed. Move the paper back and forth until you can see the "O." Continue to do the same until the "O" disappears.)
Just how do we see color? The answer to this lies within the nerve fibers of the retina. The eye has sensors that vibrate based on the incoming amount of light and color. These sensors are rods and cones, respectively. The rods help with nighttime viewing and respond nicely to dim light, whereas the cones are effective for daytime light and determining colors. Color is broken up into different levels of light, or frequencies. There are three kinds of cones, each being stimulated by a different frequency: low frequency light (such as red), middle frequency (green), and high frequency (blue). Try another quick experiment. Stand on the sidewalk looking in the direction of the flow of traffic. Wait for a car to approach and without looking behind you, see how far ahead the car gets before you actually make out the color of the car. What do you see first, the shape of the car or the color of the car? You'll notice that you will make out the shape of the car faster than the color. The reason lies in the rods and cones. Most rods are located around the perimeter of your eye and are responsible for peripheral vision. Most cones are found in the center of your eye, and pick up the center of your field of vision.
Light is part of the electromagnetic spectrum (EM). The EM spectrum consists of the following electromagnetic waves based on the property of their wavelengths: radio waves, infrared, visible light, ultra-violet, x-rays, and gamma rays. Within the visible light band, the color spectrum can be found. As mentioned earlier, the colors are classified based on their frequency with red being on the lower end of the spectrum and blue on the higher end. "ROY G BIV" is a popular way to remember the order of the colors in order from low to high: Red, Orange, Yellow, Green, Blue, Indigo, and Violet. We see the colors because they reflect light and absorb all other colors. A bright red car reflects red light back to your eyes and absorbs all other colors. So what about the color white? If we combine the colors of light, we get white. White is being reflected across all colors of the visible spectrum.
The opposite is happening with black. When we see a black sports car, all the colors of the visible spectrum are being absorbed and reflect very little light back to the eye.
As we have found, mixing the seven major colors of the visible spectrum will form white light. We can make white light also by taking red, green and blue. If we were to divide the color spectrum up into thirds, based on solar frequencies, we would find the split to be at red, green and blue. The best way of showing this phenomenon is to get red, green and blue slide projector filters; overlapping each color, you will find that the center will indeed be white. Thus we can say that red, green and blue are the three primary colors of light (or additive primaries). We can go further and say the following about light: Red + Blue = Magenta; Blue + Green = Cyan; Green + Red = Yellow.
People in the art profession follow a different rule when it comes to mixing color. They know that when they mix up a variety of colors you do not get white, but rather black. Artists use what are called pigments. Pigments are powdered materials mixed with water or oil that are used to make paints. With pigments, some colors are absorbed and others are reflected. In general the colors of pigments are determined by the colors they reflect. The three primary colors of pigments (called artist's primaries or subtractive primaries) magenta, cyan and yellow. Mixing these primary colors you will get black. Mixing yellow and cyan, cyan and magenta, and magenta and yellow will get you green, blue and red respectively.
We've all hear the phrase "seeing isn't always believing." When it comes to illusions, there is much truth to that phrase. The best explanation to why illusions work goes back to our previous discussion involving rods and cones. When you need to look more closely at an object's color, you need to turn your head in that direction to get a better look because the cones are located towards the center of the retina. Once you get the eye focused on the color, especially complentary colors (the opposites of the primary colors), your eye can get tired and will began to play tricks. This is a good example of "after images." (Figure 4 shows an example of this illusion called Herman's Grid. Stare at the diagram for 30 seconds and then turn your head onto a while wall or paper. You should see a bunch of gray dots on the paper. These dots are the after image, but the dots are not real!)
Another kind of illusion does not deal with color. Instead these illusions deal with lines and spaces. Look at Figure 5. Which line is longer, the one on the right or the one on the left? If you take out a ruler, you will find out they are the same size. The arrows which are pointing outwards make the eye expand further than is necessary, thus creating the illusion that it is bigger.
Quotes to Ponder…
Think about these quotes as you understand the world of illusions:
- "The eyes and the ears are bad witnesses when they are at the service of minds that do not understand their language." - Parmenides (500 BC)
- "The mind sees and the mind hears. The rest is blind and deaf." - Epicharmus (450 BC)
- "The explaination of the possibility of illusions lies in the fact that we transfer the notion of external objects, which would be correct under normal conditions, to cases in which unusual circumstances have altered the retinal picture." - Hermann von Helmholtz (1881)
*all quotes from Coren's Seeing is Deceiving
Lens of eye Retina
Object ImageFigure 2
X O
Figure 3
Figure 4
Figure 5
Implementation:
This curriculum can be taught over a two-week time period. The following is a list of lesson plans that can be used for teaching about light, color and perception. The order of the lessons will be left to the discretion of the teacher.
Lesson #1: "Understanding Color Pigments and Their Mixtures" (Time needed: 20 minutes)- Students will receive a visual demonstration in the three primary colors of pigment (magenta, cyan, and yellow) and their corresponding mixing colors (red, green, purple). Teacher will need to have at least six transparent plastic cups, water, and food coloring. Pour water into each of the cups. Add a couple drops of the red food coloring to one cup. In the other cups, do the same for the other colors. Place a chart on the board labeling each row and column with a color. The rest of the chart is to be filled in as you combine colors. This is a simple, yet effective classroom activity because it teaches kids how to set up charts and use them properly in experiments.
Lesson #2: "Computer Lab Days" (Time needed: 2 days) - Day 1: Have students go to the following web page: http://library.thinkquest.org/Jo11336/home.htm This is a good site for an introduction to optical illusions. Have students search this site and try some of the illusions. Set some goals for students to help them stay focused on the task. Possible goals to set: What are some of the ways optical illusions can be used and seen in life? Give an example of each of the eight types of illusions. Using the glossary, select five words and define them in your own words. Day 2: Students are to go to the following web address: http://www.illusionworks.com This is another excellent site devoted to optical illusions. Again, set goals for students and have them explore this site. One particular area on this site to note is the "Interactive Demonstrations" link. This link will take viewers to illusions that move or within the viewer can control. My particular favorites are the "Cast Shadow and Ball" illusion and the "Breathing Square." Let students have fun with these two sites.
Lesson #3: "A Day of Just Illusions" (Time needed: 1 day) - There are many books and web sites out there containing pictures and line art drawings of optical illusions. Make transparencies of at least 15 illusions. Have students take two sheets of paper out and give the following direction: "What you are going to see on the overhead are different optical illusions. As soon as I uncover the picture of the illusion, look at it very quickly, I want you to write down the very first thing that comes to your mind and what you see. When I call time, put your pens/pencils down and re-look at the illusion for another minute. After that minute is over, I want you to write down what you see. Has it changed? If so, how?" Follow this process for each of the illusions. Once each illusion is shown and students have had time to write, go back to each transparency and ask students what they saw. WARNING: This activity may lead to headaches for some students. Allow a quick "eye resting" break after every three or four illusions.
Lesson #4: "Reflecting Art" (Time needed: 3 days) - Obtain some 33" by 27" grid paper at office/art supplies stores. These grids have one-inch squares. Have students fold the paper into four equal sections (fold in half horizontally then fold in half vertically). Have students focus on just the first quadrant, the upper left hand corner of their grid paper. They are to cover up the whole first section with drawings of polygonal shapes. Remember, a polygon is closed, three or more sided, straight-edged and has vertices figure. Every shape must connect and there cannot be any gaps in the paper. The shapes should not be too small. A reasonable number of shapes would be 30 in one quadrant. Once they finish the first quadrant and its design, they must now do a vertical reflection to the right of that design. This means in the second quadrant, the upper right hand corner, the student is to make a mirror image of that in the first quadrant. All shapes and lines should be in the opposite direction from the first. Once this step is finished, continue the process of reflection. From the second quadrant, students are to make a horizontal reflection downwards to the third quadrant. And finally, from the third to the fourth quadrant it will be a vertical reflection left. Once the general sketch is done, have students go back to the first quadrant and color the shapes. There are only two rules. No two shapes side by side should be the same color, and don't choose a mixture of all dark or all light colors. Mix the lights and darks up - spread the colors out. Have then color the rest of the other quadrants but remember, - each quadrant is a mirror image of the previous. The colors should match each shape from each quadrant! An excellent project for students and the results are remarkable!
Lesson #5: "Analyzing Perspective in Artwork" (Time needed: 1 day) - Make transparencies of different illusions in art. Some notable ones: Escher's The Waterfall and Hand With Reflecting Globe, Hogarth's False Perspective, del Prete's The Window. Put the picture on the overhead and ask the students to write three to four sentences on the following questions: What is the artist telling the viewer? What do you think the artist was thinking when he/she was drawing the picture? What is so unusual about the picture? Where are the illusions taking place?
Lesson #6: "The Circle" (Time needed: 1 day) - On a paper make a two-inch diameter circle and place it about four inches from the bottom of the page. Make copies of this paper and distribute it to the students. The student's task is to use what they have learned about perspective and shadowing and make the circle "come to life." They must make the circle appear three dimensional, to move, to bounce, etc... After they finish with their work, have them share with a partner what they did. They may want to color and add background material to this drawing.
Lesson #7: "Color Pinwheel" (Time needed: 1 day) - Using white poster board, cut out a six-inch diameter circle for each student. A large coffee can would be an excellent source to trace from. Students are to divide the circle up into equal parts (like a Pie chart). They need to have a minimum of three equal parts. Using color pencils or markers have them pick out colors of the spectrum and color each part. Next poke out two small holes towards the center of the circle, spacing them about 1/2 inch apart. Get a 15" long string and loop the string through under and over each of the holes. Tie a knot with the two loose ends. Pull a portion of the string through so that the circle is in the center of the string. Spin the wheel until the string is fairly tight. Release the wheel and move your hands back and forth allowing the wheel to spin. This will take practice! Observe the colors on the wheel.
New Mexico Standards:
Art (5-8)
Content Standard 2: Use dance, music, theater/drama, and visual arts to express ideas.
Content Standard 3: Integrate understanding of visual and performing arts by seeking connections and parallels among arts disciplines as well as all other content areas.
New Mexico Standards
Science (5-8)
Content Standard 6: Students will acquire the ability to do scientific inquiry.
Content Standard 9: Students will know and understand the concepts of energy and the transformation of energy. Bibliography
For Teachers
Ades, Dawn ed. Dali's Optical Illusions. New Haven and London: Yale University Press. 2000.
Britton, Jill. Symmetry and Tessellations. New York: Dale Seymour Publications. 2000.
Coren, Stanley and Joan Stern Girgus. Seeing Is Deceiving: The Psychology of Visual Illusions. New Jersey: Lawrence Erlbaum Associates. 1978
Faulk, David and Dieter R. Brill and David G. Stork. Seeing the Light: Optics In Nature, Photography, Color, Vision, and Holography. New York: John Wiley and Sons. 1986.
Gombrich, E.H., Julian Hochberg and Max Black. Art, Perception, and Reality. Baltimore: The John Hopkins University Press. 1972.
Hewitt, Paul. Conceptual Physics. Massachusetts: Addison-Wesley. 1998
Luckiesh, M. Visual Illusions: Their Causes, Characteristics and Applications. New York: Dover Publications. 1965.
Shepard, Roger N. Mind Sights: Original Visual Illusions, Ambiguities, and Other Anomalies. New York: W.H. Freeman and Company. 1960.
Shlain, Leonard Art and Physics: Parallel Visions in Space, Time and Light. New York: Morrow. 1991.
Stafford, Barbara M. Artful Science: Enlightenment Entertainment and the Eclipse of Visual Education. Cambridge: The MIT Press. 1994.
Tolansky, S. Optical Illusions. Oxford: Pergamon Press. 1964.
For Students
Beeler, Nelson F. and Franklyn M.Branley. Experiments in Optical Illusions. New York: Thomas Y. Crowell Company. 1951.
Cobb, Vicki. How to Really Fool Yourself: Illusions for All Your Senses. New York: HarperCollins Publishers. 1981.
Escher, M.C. M.C. Escher: The Graphic Work. Germany: Barnes and Nobles, Inc. 2000.
Gibson, Gary. Science For Fun: Light and Color with Easy-To-Make Scientific Projects. Connecticut: Copper Beech Books. 1994
McLaughlin, Charles W. and Marilyn Thompson. Physical Science. New York: Glencoe Publishing. 1999.
Wick, Walter. Walter Wick's Optical Tricks. New York: Scholastic Inc.1998.
