By Miguel Cortinas and Ryan Longo

Optical Illusions

Main Objective

• Explain the idea of optical illusions and

their cause.

Introduction to Optical

Illusions

• 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.

Literal Illusions

• Literal optical illusion 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.

Physiological Illusions

• 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.

Cognitive Illusions

• 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.

Idea of Optical Illusions• 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.

Don’t Believe Your Eyes

• 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.

Illusions

• 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.

Hallucinations

• Hallucination is a false perception.

• In hallucination, no external stimulus is present. Hallucinations are

caused by internal stimulations.

• Hallucination is a personal experience.

• Hallucinations are mostly confined to mentally ill persons and to

those people under the influence of drugs. The character of

hallucination is determined by the individual's present and previous

experiences.

• The same situation may not arouse hallucination in all. There are

individual differences with regard to hallucination. The same

individual may experience different hallucinations are different

occasions also.

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.

Is It A Rabbit or A Duck??

Any Questions??

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?