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Optical Illusions

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by

Emily Nguyen

on 15 January 2015

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Transcript of Optical Illusions

Optical Illusions
Introduction
My DRIVE project topic is about optical illusions.

The essential question is about how the brain and eyes
process illusions, or images.
Main Topics To Be Discussed
Basic information about optical illusions.
What are optical illusions?
When were optical illusions discovered?
Where were the optical illusions discovered?
Who are the main researchers studying optical illusions?
Why did I choose to research optical illusions?
How were optical illusions used, or how did they help others?
What Is An Optical Illusion/What
Is My Topic About?
Definition: Optical illusions are images that are used to trick or deceive people by using our past experiences.
They can be used to make people think what is and what is not real.
Example Of An Optical Illusion
Why Is It An Illusion?
The top line is larger than the bottom line because the railroad track is getting farther in distance.
The bottom line is smaller than the top line because the railroad track is closer and larger in our perspective.
In reality, the two lines are the same size.
See what happened there? The optical illusion uses common knowledge about distance to trick us.
This railroad track illusion discovered by Mario Ponzo shows that the top line is larger than the smaller bottom line.

Step One
Light bounces off of the walls and object from the image and enters the eye.
Step Two
The light goes through the pupil and lens to the retina at the back of the eye.
Step Three
Inside the retina, the light makes the image upside-down and backwards.
Step Four
The retina uses light sensitive cells to change the image into a message for the brain to understand.
The optic nerve carries the message to the brain, inside the visual cortex.
How Does The Brain And Eyes Process Images?
How Do We See Optical Illusions?
A fast five-step process is used to send a message from the eye to the brain.
The process mostly takes place in the retina.
The image or optical illusion is viewed in the visual cortex of the brain.
What Is The Visual Cortex?
It is where the images are received and are processed for viewing.
It is located in the lower right at the back of the brain.
When Were Optical Illusions First Discovered?
The Stone Age
Ancient Greece
The Stone Age
Ancient Greece
In 5th century B.C, Greek philosopher, Epicharmus, thought that even if our mind knows and understands everything clearly, the sensory organs deceive us.
Ancient Greece
Another Greek philosopher in the same time period named Protagoras thought differently and says that the environment fools us and not the senses.
Ancient Greece
In 350 B.C, the famous Greek philosopher, Aristotle, said it was possible to fool the senses easily, agreeing with Protagoras.
What Happened?
Through the course of these times, the Greeks gained a lot of knowledge about optical illusions.
Many of the Greeks had a lot of logical theories.
Step Five
What Is My Topic About? Cont.
Three things about optical illusions you should know:
Why Do Optical Illusions Use Past Experiences?
In order to get closer to the viewer, optical illusions use past experiences of what we already know to use against us.
How Do We Get Tricked Easily?
One way people get tricked easily is by their blind spot.
A blind spot is where the eye cannot see or detect light.
The blind spot can miss things, and the other eye can pick the missing information.
Blind spots are an advantage to trick us.
What Are The Different Types Of Illusions?
Optical illusions use different types of illusions to trick us.
How do we get tricked easily?
What are the different types of illusions?
Why do optical illusions use past experiences?
Brightness
Tilt
Color
Movement
Archaeologist, Duncan Caldwell, discovered recurring images on cave walls, found to be optical illusions.
The lighter gray is the bison, while the darker gray is the mammoth.
Who Were The Main Researchers In Optical Illusions?
Aristotle
Richard Gregory
Ludimar Hermann
Aristotle
He is a main researcher for his studies and theories about optical illusions.
An example of an illusion he discovered is the motion aftereffect, where he looked at a stream going down but when he looked at the rocks beside it, it was going up.
Richard Gregory
Gregory is psychologist who is famous for his contribution in cognitive psychology, the study of mental processes like memory.
An example of an illusion he rediscovered was the cafe wall illusion.
Ludimar Hermann
He is a physiologist known for his research, and has made large discoveries, such as the Hermann Grid illusion.
Not only is he known for optical illusions, but also about the human body.
Is That All?
Based off of their discovery of an optical illusion and contribution, are the main researchers:
Is That It?
How the brain and eyes process images seems like a complicated task, but it is faster than the blink of an eye!
Why Is It An Optical
Illusion?
The two species of animals are mixed to show one and the other easily.
For example, one side is the mammoth and the other is the bison.
Aristotle's Discoveries
If you cross two finger and touch an object like a pen, it seems like you are touching two pens.
The Oppel-Kundt illusion, where it looks like the distance from A-B is longer than B-C.
Gregory's Cafe Wall Illusion
Gregory's illusion where the rows look staggered.
Hermann's Grid Illusion
Herman's illusion, where black dots disappear and appear rapidly at intersections.
There are many more researchers who have contributed a lot, but these three were the few who discovered famous illusions.
Where Have Optical Illusions Been Researched
Or Discovered?

Ancient Greece
Most of the first discoveries about optical illusions, studies, and theories were found in Ancient Greece.
Cave Font-De-Gaume
The mammoth-bison optical illusion has also been discovered in the cave named Font-De-Gaume in the Stone Ages.
College
Lots of research has been done at colleges, such as research about neuroscience.
For example, Edward Adelson created the checker shadow illusion as a professor in MIT.
Where Have Discoveries And Research Been Found?
Some of the places include:
Ancient Greece
Cave Font-De-Gauma
Colleges
Only Three Places?
Optical Illusions have been found in many more places, but these three are the most significant.
Why Were Optical Illusions Studied?
They were caused by people's interest. Examples include Greek philosophers and scientists in the 19th century.
Greek Philosophers
When the Greek philosopher, Epicharmus, had an explanation of the phenomenon, others had different views about it.
The confusion of optical illusions increased their curiosity.
Over time, knowledge about illusions grew.
19th Century Scientists
In the 19th century, scientists grew interest about perception.
Illusions were used as tools to study perception.
To find out more, they studied misperceptions and tried to figure out the principles of perception.
Modern Day
In modern day, scientists are far ahead the Greeks and the 19th century scientists.
Now, some of them study cognitive processes like vision, attention, memory, creativity, consciousness, and perceptual development.
How Has Optical Illusions Been Used Or Improved Life?
Today, optical illusions have been used many ways.
For example, entertainment, research, careers, and even art.
Art
Optical illusions have been used as art, like M.C Escher's drawings.
In Ancient Greece, optical illusions were used for building temples in order to seem perfectly straight.
Entertainment
Optical illusions are also used in magic shows to trick the audience into believing what is or is not real.
For example, a card that is being pulled out that is the same card someone chose is always a trick.
To the viewer it looks real, but to the magician it is not.
Career
A scientist can use neuroscience to study the nervous system and help others with their research.
Helping Others
It makes a person think harder and gives them a benefit of seeing something in a different way.
It also helps them see how not to get tricked by optical illusions.
Conclusion
Overall Summary
Optical illusions are used to trick and deceive people, also using past experiences to do so.
Ancient Greeks were an important role in optical illusions, for example, increasing knowledge about it.
Many scientists and researchers contributed to optical illusions and discovered their own.
Optical illusions are used in everyday life.
Overall Summary Cont.
Images go through a quick five step process through the brain and eyes.
What now?
Now that you know how optical illusions trick us and everything else about it, can you prevent one from tricking you?
A little more challenging is - can you spot any optical illusions around you right now?
Good luck!
Full transcript