The student will learn how hallucinogens cause visual misperception and hallucinations.
Have students draw a bull's-eye onto a sheet of unruled white paper. Make a small "X" at the center of another sheet of paper. Now, have the students stare at the bull's-eye for about 20 seconds and then quickly shift their focus to the "X". Students will find that an after-image of the bull's-eye will appear. Explain that after-images are a class of optical illusions, which have some similarity to hallucinations. Have students search the Internet and other sources for information about drug-induced hallucinations and prepare a report summarizing their findings.