1. Optical Illusions
By Miguel Cortinas and Ryan Longo

2. Main Objective
• Explain the idea of optical illusions and
their cause.

3. Introduction to Optical
Illusions
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Optical Illusion- (visual illusion) caused by visually
perceived images that differ from reality.
The information gathered by the eye is processed in the brain
to give a perception that does not match up with the physical
measurement of the stimulus source.
Three main types: Literal, Physiological, and Cognitive.

4. Literal Illusions
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Literal optical illusions are
images that differ from the
objects that create them.
Artists may use objects
such as fruit or foliage to
create a portraiture or
scenery.

5. Physiological Illusions
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Physiological illusions are
the effects on the eyes and
brain of excessive
stimulation of a specific
type.
Artists may use color or
movement to confuse the
viewers' eyes and brains.

6. Cognitive Illusions
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Cognitive illusions are
where the eye and brain
make unconscious
inferences.
They can also be known as
"mind games".
Perspective and color
heavily influence this
genre.

7. Idea of Optical Illusions
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When we witness an illusion, we perceive something that
does not correspond to what is actually out there—what exists
in the real world.
Illusions fool us! They convince us of things that are not true.
Dictionary definitions of illusion usually state that an illusion
is a sensory perception that causes a false or distorted
impression, or a misrepresentation of a "real" sensory
stimulus.

8. Don’t Believe Your Eyes
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Illusions are misperceptions that are perceived by most
people, and are based on a specific stimulus received under
certain conditions.
Some experiments with animals indicate that several species
of mammals and birds are "fooled" by illusions in much the
same way we are.
Illusions are different from both hallucinations and delusions.

9. Illusions
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Illusion is a kind of wrong perception.
In illusion, an external stimulus is always present. In other
words, illusions are caused by external stimulations.
Illusion is almost universal.
The same situation arouses the same type of illusion in most
people.

10. Hallucinations
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Hallucination is a false perception.
In hallucinations, no external stimulus is present. Hallucinations are
caused by internal stimulations.
A hallucination is seeing, hearing, tasting, smelling or feeling things
that do not really exist.
Certain drugs can cause hallucinations. Certain mental illnesses
can also cause hallucinations. People who have hallucinations are
not necessarily ill, lack of sleep can also cause hallucinations.
People who have hallucinations are not necessarily ill, lack of sleep
can also cause hallucinations. Hallucinations just before going to
sleep or just after waking up are considered normal.

12. Examples
This just looks like a
normal triangle right?
But where does it end?
At first look this cube
looks fine, but look at
the center stem.

13. Is It A Rabbit or A Duck??

14. Evaluation Questions
1. What is an optical illusion?
2.
What are the causes of optical illusions?
3.
What are the 3 types of illusions?
4. How do optical illusions differ from hallucinations and
delusions?

15. Any Questions??

16. Bibliography
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Block, J. (n.d.). What is an Illusion?.sandlotscience.com. Retrieved
October 29, 2013, from
http://www.sandlotscience.com/EyeonIllusions/whatisanillusion.htm
Nierenberg, C. (n.d.). Optical Illusions: When Your Brain Can't Believe
Your Eyes. ABC News. Retrieved October 29, 2013, from
http://abcnews.go.com/Health/EyeHealth/optical-illusions-eye-brainagree/story?id=8455573
Nin, A. (n.d.). Causes of Optical Illusions.buzzle.com. Retrieved October
29, 2013, from http://www.buzzle.com/articles/causes-of-opticalillusions.html