1. Art Technologies Unit 1 Lesson 5

2. In this lesson you will learn…  How optical illusions work  How optical illusions are really “errors in perception”  How optical illusions are used to communicate and entertain

3. Optical Illusions The nature of our vision and the working relationship between the eyes and the brain cause optical illusions to occur. Artists create illusions of reality all the time. They represent what they see in the real 3D world on a flat surface.

4. Stare at this picture…

5.  Some think that optical illusions are vision-tricks.  Really, they are “errors in perception” or mistakes in our visual perception.  There are different types of illusions: 1.Refraction of light illusion 2.Closure illusion 3.Figure/ground illusion 4.Necker cube illusion 5.Linear perspective illusions

6. Refraction of Light Illusions  Light has the ability to bend, or refract.  Have you noticed how a straw or spoon leaning in a glass of water appears to be broken or bent?

7. Closure Illusions  Our eyes and brain have the ability to get together and fill in the missing details of an image.  In the same way, our visions allows us to see movies as continuous rather than a jerky series of still pictures.

8. Figure/Ground Illusion  Which part of the picture is the SUBJECT and which is the BACKGROUND?  There is more than one way for use to perceive this kind of illusion.

9. Necker Cube Illusion  Similar to figure/ground illusion.  It’s not easy to decide which side of the cube is the front and which is the back.

10. Linear Perspective Illusions  Common in art.  By making what should be parallel lines appearing to come together in the distance, artists make a flat surface appear to have depth.

11.  Illusions are useful for communication and entertainment.  Learning how to create and manipulate optical illusions is one of the key skills of the artist, craftsperson, or designer.  Here’s a print by NL artist Bill Ritchie, which hides images within an image.

12. Look at this digital optical illusion. Stare at the image. See if you can coax another image out from the background.

13. Other Illusions…  Negative afterimage  Moire illusions  Tetchier illusion  Ambi grams  Stereo gram

14. Check out these illusion sites:  http://www.sandlotscience.com/ http://www.sandlotscience.com/  http://www.exploratorium.edu/exhibits/f_exhibits.html http://www.exploratorium.edu/exhibits/f_exhibits.html

15. Lesson 5 Assignment  Create an optical illusion!  Using Paint or another computer program, try to re-create 2 optical illusions of your interest.