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Lesson of The Week- 

Quote of the Day:

 

Do not be misled by what you see around you, or be influenced by what you see. You live in a world which is a playground of illusion, full of false paths, false values and false ideals. But you are not part of that world.
              Sai Baba

 

 See you all next week!    Smile, laugh and enjoy your life and learning!

 Aloha- I guess I'm still in a playful mood from last week...maybe I just really enjoy this time of year??!!  Anyway this week lets have some fun with "Optical Illusions" and see how much we really can trust our own eyes.  My friend says these optical illusion pictures give him a headache...I wonder how many people feel the same? I actually enjoy looking at them and many years ago enjoyed drawing them as well. 

Theme: Optical Illusions

 Optical Illusions

 

An optical illusion (also called a visual illusion) is characterized by visually perceived images that differ from objective reality. The information gathered by the eye is processed in the brain to give a percept that does not tally with a physical measurement of the stimulus source. There are three main types: literal optical illusions that create images that are different from the objects that make them, physiological ones that are the effects on the eyes and brain of excessive stimulation of a specific type (brightness, tilt, color, movement), and cognitive illusions where the eye and brain make unconscious inferences. They can also be known as "mind games".

 

Physiological illusions, such as the afterimages following bright lights, or adapting stimuli of excessively longer alternating patterns (contingent perceptual aftereffect), are presumed to be the effects on the eyes or brain of excessive stimulation of a specific type - brightness, tilt, color, movement, etc. The theory is that stimuli have individual dedicated neural paths in the early stages of visual processing, and that repetitive stimulation of only one or a few channels causes a physiological imbalance that alters perception.

The Hermann grid illusion and Mach bands are two illusions that are best explained using a biological approach. Lateral inhibition, where in the receptive field of the retina light and dark receptors compete with one another to become active, has been used to explain why we see bands of increased brightness at the edge of a color difference when viewing Mach bands. Once a receptor is active it inhibits adjacent receptors. This inhibition creates contrast, highlighting edges. In the Hermann grid illusion the gray spots appear at the intersection because of the inhibitory response which occurs as a result of the increased dark surround. Lateral inhibition has also been used to explain the Hermann grid illusion, but this has been disproved.

 

Cognitive illusions are assumed to arise by interaction with assumptions about the world, leading to "unconscious inferences", an idea first suggested in the 19th century by Hermann Helmholtz. Cognitive illusions are commonly divided into ambiguous illusions, distorting illusions, paradox illusions, or fiction illusions.

Ambiguous illusions are pictures or objects that elicit a perceptual 'switch' between the alternative interpretations. The Necker cube is a well known example; another instance is the Rubin vase. Distorting illusions are characterized by distortions of size, length, or curvature. A striking example is the Café wall illusion. Another example is the famous Müller-Lyer illusion. Paradox illusions are generated by objects that are paradoxical or impossible, such as the Penrose triangle or impossible staircases seen, for example, in M. C. Escher's Ascending and Descending and Waterfall. The triangle is an illusion dependent on a cognitive misunderstanding that adjacent edges must join.
  • Fictional illusions are defined as the perception of objects that are genuinely not there to all but a single observer, such as those induced by schizophrenia or a hallucinogen. These are more properly called hallucinations.

    • Reading

    Answer the following questions in your journal.  Try to write complete and detailed answers.

     

    1. How would you explain an optical illusion to someone who has never

        seen one?

     

    2. Can you think of some situations where optical illusions are used in

        everyday life?

     

    3. What's the difference between an optical illusion and a hullucination?

     

    4. Are we tricking the brain or tricking the eye?

     

    5. How do these words relate to optical illusions...mirage...infinity pool...camouflage?

     

     

     

     

    Listening

    Challenge

     

     

    1. Watch this video

     

    2. If you encounter a word or phrase you don't know...go back and listen again.

     

    3. If you still can't understand write it down and look it up. (if you can) Or ask someone.

     

    4. Listen again until you can listen from start to finish with a general understanding.

    Writing

    Is there a white triangle in this picture or do we just imagine it?

    Can you see this ballet dancer spins both ways? Look away and look back.

    The orange dots are exactly the same size.  Go ahead and measure.

    Stare at the + and a green ball moves around the circle...stare at the pink and the green is gone!

    Duck or Rabbit?

    Chalk Art Artist's have used the optical illusion techniques to create amazing flat paintings in 3D. Take a Look.