NOVA scienceNOW: Profile: Hany Farid Explore optical illusions:
You can't always believe your eyes. Consider, for example,
optical illusions. Optical illusions play with the visual clues
we use to interpret what our eyes see. As the segment shows,
Hany Farid also takes advantages of visual clues—clues that tell
him that what we are seeing isn't to be believed. Show students
a series of optical illusions: Use the "See also" links at the
bottom of the page to move through the illusions and explore how
each one tricks the eye. Have students study the "Bump"
illusion, which illustrates how our eyes and brain use shadows
and the positions of light sources to interpret what we see. Ask
students to describe which direction the light is coming from if
the they are seeing a depression or a raised figure. In the
video, Farid describes how he uses shadows and light sources to
spot faked images. While watching the segment, have students
record the kinds of clues Hany uses to recognize faked images.
Create a faked image: