Nicholas Academy
Google
 
Web nicholasacademy.com


Science | Science Experiment of the Week | 240 - Waterfall Effect
Optical Illusions Brain's Motion Detectors

 









This Week's Experiment - #240 Waterfall Effect

This week's experiment is one that I have wanted to share with you for a long time. The problem has been finding a way for you to see it. To really get the biggest impact, you need a large waterfall. Realizing that most of you do not have one of these in your back yard, I have been searching for other ways for you to see this wonderful optical effect. You will need:

One of the following:
a waterfall
a television
access to websites

If you happen to have a waterfall nearby, you are all set. You need to be dow nstream of the waterfall, looking up at it. Stare at the falling water for about 30 seconds. Then look at some nearby trees or a building. What you see should impress you. A vertical strip of the trees will seem to flow upwards! I first saw this at Fall Creek Falls in Tennessee. At the time, I had never heard of the waterfall effect and it gave me quite a challenge chasing down an amazing mystery in those days long before the ease of Internet research.

If you don't have a waterfall, you can also use your television. Many of the news channels now have scrolling bands of text at the bottom of the screen. As the words move across the screen, they are a reasonable substitute for the waterfall. Stare at a point in the middle of this band of moving words for about 30 seconds and then look at a picture or something with a nice pattern. You will see a horizontal band of the pattern seem to flow sideways. Not quite as impressive as a waterfall, but still pretty neat.

If you have access to websites, you are in for a wonderful treat. There are quite a few websites which have rotating spirals which use the waterfall effect to produce some spectacular illusions. One of the sites is:

dogfeathers.com

After staring at the spiral for about 15 seconds, look at a picture of something with a pattern. I found woodgrain on the panels of my wall did very well. For a special treat, stare at the spiral and then look at the back of your hand! Be prepared to be startled.

Why do you see this? The reason is related to the color reversals that we saw in last week's experiment. In looking at the strangely colored flag, you "fatigued" the color receptors in your eyes. Staring at something that is yellow desensitizes the cells in your eye to yellow. When you then look at something that is white (a mix of all the colors), the signals that report the yellow part of the light are weaker than the others. This causes the white paper to look blue, as you see the spectrum with the yellow taken out.

A similar thing is happening as you stare at the motion. The big difference here is that the "fatigue" happens in your brain, not in your eyes. The part of your brain that deciphers the impulses from your eyes into sight also detects motion. These "motion detectors" are direction specific. If the signal from the upwards motion detectors are stronger, your brain recognizes it as upwards motion. If the right motion sensors are stronger, you see movement to the right. If all of the signals are the same strength, you don't see any motion.

If one part of your vision continually sees motion downwards, while the rest of your vision sees stationary objects, the part that sees the motion becomes fatigued. As the nerves fire continuously, the signal weakens. If you then look at a stationary pattern, the signals would normally return to all the same strength, but instead, the downwards sensors are tired and their signal is weaker. The normal signal from the upwards sensors is stronger and tells your brain that you are seeing things move upwards.

From Robert Krampf's Science Education Company
PO Box 60982
Jacksonville, FL 32236-0982
904-388-6381
krampf@aol.com


Science Experiments Index
211 - 220 221 - 230 231 - 240 241 - 250
251 - 260 261 - 270 271 - 280 281 - 290
291 - 300 301 - 310 311 - 320 321 - 330
331 - 340 341 - 350 351 - 360 361 - 370




Zoobooks Magazine


BookCloseOuts.com


Shop The Space Store for Toys and Games

Nicholas Academy Index

Middle Age & Renaissance

Artists, wars, armour, castle games, recipes, geography, quizzes, fashions, pictures of weapons, music, old world maps, women of medieval times, medicine, language, and more.

Foreign Language

Arabic, German, Japanese, Spanish, French, Italian, Latin, Russian. Games, free software downloads, free online lessons, newspapers, discussion groups, articles, history, culture, quizzes.

Language Arts

Play language arts games, improve your vocabulary, create customized puzzles, make your own book! Download free software in the form of shareware, freeware, and demos.

Math

Math games, quizzes, fun websites, printable charts, coloring books, tools. Algebra, geometry, fractions, multiplication.

Music

Play music games, take free music lessons, explore music theory and history, find great posters.

Creativity

Explore animation, filmmaking, build online cities, create and share works of art, write stories, create your own web site, read creativity articles.

Science

Science games and quizzes, fun science websites, posters, coloring books, kits, experiments, forensics labs and more.

Social Studies

Coloring books, countries of the world, games and quizzes, software downloads, posters, computer jigsaw puzzles, printables.

Science Experiments

Science can be fun and understandable. Free Experiment of the Week, featuring experiments that are unusual, safe, dramatic, cheap, and fun. From Robert Kramp's Science Education Co.

Space Items for Kids

Fun and affordable space items for kids, including toys, games, kits, food products, and more.

Fun Science Kits

Educational science kits kids will love! Early science kit, DNA explorer kit, robot challenge, forensic lab, volcano kits, crystals.

Fun Electronic Kits

All in one project labs, light kits, sound kits, motion and metal detectors, clap on/off kit, nerve tester and shocker.

Educational Posters

Civil rights, African American writers, parts of speech, medieval, periodic table of elements, music, astronomy, world maps with flags, literature, poetry, dinosaurs, biology, cats, Japanese anime.

Educational Coloring Books

Coloring books for kids and adults. Civil war, plants, animals, states, middle ages, cultures, geometric designs, puzzles.

Courses

Online, via email or through the regular mail. College, accredited high school, free reading and phonics courses, foreign language, history, religion, and more.

Exercises

Test your knowledge with these fast, fun, and educational quizzes. Roman numeral addition, world capitals, presidents in order, the elements, world flags, and more.

Printables

Roman numerals, addition, multiplication, order of statehood, state and world capitals, order of presidents, chemical elements, parts of speech, spanish numbers.

Useful Tools

Reading systems, loan programs, flashcard, worksheet and test makers, game creators, free curriculum, board games, percentage calculator, a puzzle creator and more.

Testing & Assessment

SAT, GED, ACT, practice tests, exam preparation. Standardized test practice, content standards listed by state, sample items, scope and sequence, aptitude, essential skills.

Bargain Books

New and used low cost books and textbooks. Websites with open source books and loan programs.

Website Building

Templates, ideas for personal, educational, children's, business sites, design tips and tools, registration and hosting information, step-by-step instructions, quick and easy web page, web building just for kids.

Freebies & Bargains

Books, posters, videos, software kits, curriculum, courses. Save on teaching supplies, receive free educational materials.

Site Map

This site map lists nearly every page on our site, along with a short description.
   


Educational Poster Store

Hundreds of educational posters in different subject areas. Parts of speech, medieval, solar system, biology, world maps, Einstein, Martin Luther King. Science, math, literature, art, music, english, geography, social studies. If you don't know exactly what you're looking for, this is great to browse for ideas.
NASA Website Links

Educational resources include worksheets such as mazes, coloring pages, shuttle model instructions, crossword puzzles, space food tray instructions and grocery list, and more. See the Space Station Sky Watch, view a NASA Astronaut Application or the Space Shuttle Launch Schedule, learn about the U.S. Space Camp and Women in Spaceflight.
Zoobooks

Get a free Zoobooks issue and a tiger poster. Zoobooks are the all-in-one, everything-you-wanted-to-know but-didn’t-know-who-to-ask guide to the world’s most fascinating animals, birds, reptiles, and insects. For kids five to twelve.



If you have comments, questions, or would like to report a broken link,
please send an email to Cheryl at nicholas230@yahoo.com

© 2000-2009 Nicholas Academy
Nicholas Academy Site Map
privacy policy